THPRB —  Poster Session - Redback   (23-May-19   15:30—17:30)
Paper Title Page
THPRB001 Applications of Online Optimization Algorithms for Injection at the Australian Synchrotron 3795
 
  • R. Auchettl, R.T. Dowd
    AS - ANSTO, Clayton, Australia
 
  At the Australian Synchrotron, accelerator tuning predominantly occurs via manual optimization or traditional optimization techniques such as the Linear Optics from Closed Orbits (LOCO) algorithm. While we have had distinct success with the implementation of LOCO* and manual tuning, these strategies are not without their downsides. Some situations (such as the optimization of synchrotron beam dynamics) produce a design space too large and multifaceted for manual tuning while implementing LOCO can be computationally expensive. Also, without sufficient diagnostic systems, both LOCO and manual tuning do not necessarily guarantee that the optimal solution will be found. Motivated by the successful implementation of online optimization algorithms at SPEAR3**, this paper outlines the application of online optimization algorithms to improve the performance of the Australian Synchrotron injection system. We apply the efficient Robust Conjugate Direction Search (RCDS) Algorithm to reduce beam loss along the Booster-to-Storage ring (BTS) Transfer line and Storage Ring and compare against the LOCO method.
* R. Dowd et al. (2011), Phys. Rev. ST: AB, 14, 012804.
** X. Huang et al. (2013), Nucl. Instr. Meth. A., vol. 726, pp. 77-83.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB001  
About • paper received ※ 08 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB003 Automatic Classification of Post Mortem Data for Reduced Beam Down Time 3799
 
  • M.C. Chalmers, Y.E. Tan
    AS - ANSTO, Clayton, Australia
 
  Time spent recovering from faults that result in a rapid loss of stored current (a total beam loss event) can be costly to the Australian Synchrotron facility and its researchers. The identification of a fault leading to total beam loss is assisted by a large variety of investigative tools for specific tasks, but they do not often give a thorough overview of all systems required to store beam. Post mortem data uniquely provides insight into how the beam was behaving at the specific time the dump occurred. With machine learning, we find that we can automatically and rapidly identify many types of total beam loss events by learning about the unique characteristics in the post mortem files.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB003  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB004 Hardware and Firmware Development for Enhanced Orbit Diagnostics at the Australian Synchrotron 3802
 
  • S. Chen, R.B. Hogan, A. Michalczyk, A. C. Starritt, Y.E. Tan
    AS - ANSTO, Clayton, Australia
 
  The Enhanced Orbit Diagnostic (EOD) features will be an expansion to the existing Fast Orbit Feedback (FOFB) system that is currently in operation. The new system will add the capability of online cor-rector-to-position response matrix calculation; this will significantly reduce the required measurement time. The new features will allow the injection of PRBS noise or sinusoidal signals into correctors, to characterise and monitor the FOFB system’s parameters and performance and track it over time. The system will be built based on a Xilinx ZYNQ Sys-tem-on-Module (SOM) mounted on an in-house designed motherboard to which the existing FOFB daughter board is plugged into.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB004  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB005 Orbit Feedback and Beam Stability at the Australian Synchrotron 3805
 
  • A. C. Starritt, A. Pozar, Y.E. Tan
    AS - ANSTO, Clayton, Australia
 
  The Australian Synchrotron (AS) is a 3rd generation light source which has been in operation since 2006. Measurement of the storage ring’s beam position is provided by 98 beam position monitors, and corrections can be applied using 42 horizontal and 56 vertical slow corrector magnets, and 42 horizontal and 42 vertical fast corrector magnets. This paper provides a background describing the feedback strategies adopted at the AS leading to the current integrated orbit feedback system, together with a description of the beam position analyse techniques currently in use. It will also highlight some of the issues encountered with the system and how they were overcome. The paper also describes planned improvements, including the enhanced orbit diagnostics functionality we are intending to introduce in the next 12 months.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB005  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB007 Ponderomotive Instability of Self-Excited Cavity 3808
 
  • S.R. Koscielniak
    TRIUMF, Vancouver, Canada
 
  The electro-magnetic fields within a super-conducting radio frequency (SRF) cavity can be sufficiently strong to deform the cavity shape, which may lead to a ponderomotive instability. Stability criteria for the self-excited mode of cavity operation were given in 1978 by Delayen. The treatment was based on the Routh-Hurwitz analysis of the characteristic polynomial. With the Wolfram modern analytical tool, "Mathematica", we revisit the criteria for an SRF cavity equipped with amplitude and phase loops and a single microphonic mechanical mode.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB007  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB008 Ponderomotive Instability of Two Self-Excited Cavities 3812
 
  • S.R. Koscielniak
    TRIUMF, Vancouver, Canada
 
  We consider the ponderomotive instability of two superconducting RF cavities self-driven from a single RF source with vector-sum control.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB008  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB009 Vector Sum & Diffference Control of SRF Cavities 3816
 
  • S.R. Koscielniak
    TRIUMF, Vancouver, Canada
 
  We consider the ponderomotive instability of multiple superconducting RF cavities driven from a single RF source. We add vector difference control to the usual the technique of vector sum control, in order to increase the accelerating gradient threshold for ponderomotive instability.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB009  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB010 Ponderomotive Instability of Generator-Driven Cavity 3820
 
  • S.R. Koscielniak
    TRIUMF, Vancouver, Canada
 
  The electro-magnetic fields within a super-conducting radio frequency (SRF) cavity can be sufficiently strong to deform the cavity shape, which may lead to a ponderomotive instability. Stability criteria for the generator-driven mode of cavity operation were given in 1971 by Schulze. The treatment side-stepped the Routh-Hurwitz analysis of the characteristic polynomial. With the Wolfram modern analytical tool, ’Mathematica’, we revisit the criteria for an SRF cavity equipped with amplitude and phase loops and a single microphonic mechanical mode.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB010  
About • paper received ※ 14 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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THPRB011 Norm-optimal Iterative Learning Control to Cancel Beam Loading Effect on the Accelerating Field 3824
SUSPFO005   use link to see paper's listing under its alternate paper code  
 
  • Z. Shahriari, K. Fong
    TRIUMF, Vancouver, Canada
  • G.A. Dumont
    UBC, Vancouver, Canada
 
  Iterative learning control (ILC) is an open loop control strategy that improves the performance of a repetitive system through learning from previous iterations. ILC can be used to compensate for a repetitive disturbance like the beam loading effect in resonators. In this work, we aim to use norm-optimal ILC to cancel beam loading effect. Norm-optimal ILC updates the control signal with the goal of minimizing a performance index, which results in monotonic convergence. Simulation results show that this controller improves beam loading compensation compared to a PI controller.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB011  
About • paper received ※ 14 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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THPRB012 Toward Autonomous Phasing of ISAC Heavy Ion LINACs 3827
 
  • O. Shelbaya, R.A. Baartman, O.K. Kesterpresenter, S. Kiy
    TRIUMF, Vancouver, Canada
 
  Ongoing development work at TRIUMF aims to implement a model-based tuning approach for accelerators, with the goal of automation of tuning tasks and minimizing tuning times. As a part of this, work is underway toward the development of an analytical model of the linacs using the methodology of Hamiltonian based beam envelope dynamics. The TRIUMF High-Level Applications (HLA) project has been developing software that allows direct interfacing with the control system. The envelope code TRANSOPTR is now being extended to simulate the ISAC-II Superconducting Linac. Within the emerging HLA framework, this will allow for automated phasing and tuning of the linac. The steps of the model development will be presented in this contribution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB012  
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB013 The ESSnuSB Target Station 3831
 
  • E. Bouquerel, E. Baussan, L. D’Alessi, M. Dracos
    IPHC, Strasbourg Cedex 2, France
  • P. Cupial, M. Koziol
    AGH University of Science and Technology, Kraków, Poland
  • N. Vassilopoulos
    IHEP, Beijing, People’s Republic of China
 
  Funding: This project is supported by the COST Action CA15139 EuroNuNet. It has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 777419.
The ESSνSB project, recently granted by the EU H2020 programme for a 4-year design study, proposes to use the protons produced by the linac (2 GeV, 5 MW) of the European Spallation Source (ESS) currently in construction in Lund (Sweden) to deliver a neutrino super beam. It follows the studies made by the FP7 Design Study EUROν[1] (2008-2012), regarding future neutrino facilities. The primary proton beam line completing the linear accelerator will consist of one or several accumulator rings and a proton beam switchyard. The secondary beam line producing neutrinos will consist of a four-horn/target station, a decay tunnel and a beam dump. A challenging component of this project is the enormous target heat-load generated by the 5 MW proton beam. In order to reduce this heat-load there will be four targets, which will be hit in sequence by the compressed proton pulses, thereby reducing the beam power on each target to 1.25 MW. Following the EUROν studies, a packed bed of titanium spheres cooled with helium gas has become the baseline design for a Super Beam based on a 2-5 GeV proton beam with a power of up to 1 MW per target, with other targets being considered for comparison. The hadron collection will be performed by four hadron collectors (magnetic horns), one for each target. Each of these target/hadron-collector assemblies will receive proton pulses three times more frequently than in present projects, and by an average beam power of 1.25 MW, which is twice as high as in present neutrino projects. The feasibility of the target/horn station for the ESSνSB project is discussed here.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB013  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB018 Large-Scale Optical Synchronization System of the European XFEL with Femtosecond Precision 3835
 
  • T. Lamb, M.K. Czwalinna, M. Felber, C. Gerth, T. Kozak, J.M. Müller, H. Schlarb, S. Schulz, C. Sydlo, M. Titberidze, F. Zummack
    DESY, Hamburg, Germany
 
  Femtosecond pulsed optical synchronization systems have evolved over the last few years and are now a mature technique to synchronize FELs. A large-scale femtosecond-precision synchronization system with up to 44 end-stations has been constructed at the European XFEL to meet the FEL synchronization stability requirements. The synchronization system is used to phase-lock various laser systems with femtosecond accuracy, to precisely measure the electron bunch arrival time along the accelerator for fast arrival time feedbacks and to locally phase stabilize the phase of the RF reference signals for the accelerator RF controls on a femtosecond level. The architecture of the large-scale synchronization system and design choices made to achieve the reliability, maintainability and performance requirements are presented together with measurement results from the past year of operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB018  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB019 Collimation of Target Induced Halo Following MAGIX at MESA 3839
SUSPFO021   use link to see paper's listing under its alternate paper code  
 
  • B. Ledroit
    IKP, Mainz, Germany
  • K. Aulenbacher
    KPH, Mainz, Germany
  • K. Aulenbacher
    GSI, Darmstadt, Germany
  • K. Aulenbacher
    HIM, Mainz, Germany
 
  Funding: Supported by the DFG through GRK 2128
The Mainz Energy-recovering Superconducting Accelerator (MESA) will be an electron accelerator allowing operation in energy-recovery linac (ERL) mode. It provides the opportunity to operate scattering experiments at energies of ~100 MeV with thin gas-targets. The MESA Internal Gas Target Experiment (MAGIX) aims to operate windowless jet targets and different gases up to Xenon to search for possible dark photon interactions, to precisely measure the magnetic proton radius and astrophysical S-factors. Investigations on the impact of the target on beam dynamics and beam losses are required for machine safety and to examine limits to ERL operation. The goal of this work is to understand target induced halo in the different experimental setups, track halo particles through downstream sections to examine beam losses and include a suitable collimation system and shielding into the accelerator layout to protect the machine from direct and indirect damage through beam losses and radiation. The present status of the investigations is presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB019  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB020 A Feedback System to Minimize the Electron Bunch Arrival-Time Jitter Between Femtosecond Laser Pulses and Electron Bunches for Laser-Driven Plasma Wakefield Accelerators 3843
 
  • S. Mattiello, A. Penirschke
    THM, Friedberg, Germany
  • H. Schlarb
    DESY, Hamburg, Germany
 
  Funding: The work of S. Mattiello is supported by the German Federal Ministry of Education and Research (BMBF) within the Project MAKE-PWA.
In a laser driven plasma based particle accelerator a stable synchronization of the electron bunch and of the plasma wake field in the range of less than 2 fs is necessary in order to optimize the acceleration. For this purpose we are developing a new shot to shot feedback system with a time resolution of less than 1 fs*. We plane to generate stable THz pulses by optical rectification of a fraction of the plasma generating high energy laser pulses in a nonlinear lithium niobate crystal. With these pulses we will energy modulate the electron bunches shot to shot before the plasma to achieve the time resolution. In this contribution we will focus on realization aspects of the shot to shot feedback system and the lithium niobate crystal itself. Here we compare different approximations for the modeling of the generation dynamics (second order or first order calculation) and of the dielectric function (influence of the dispersion relation, of the free carries generated by the pump adsorption and their saturation, depletion of the pump) in order to investigate the importance of a detailed description of the optical properties for the THz generation.
*The feedback system will be tested at the Accelerator R&D facility SINBAD (Short Innovative Bunches and Accelerators at DESY).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB020  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB021 Automatic Loop for Carrier Suppression in Attosecond RF Receivers 3847
 
  • U. Mavrič, M. Hoffmann, F. Ludwig, H. Schlarb, L. Springer
    DESY, Hamburg, Germany
 
  The carrier suppression interferometer method can be used as a radio receiver architecture which allows for detection of RF signals in the attosecond range. The carrier suppression scheme requires an automatic carrier suppression circuit which provides stable operation of the RF receiver in the best operating point. In the poster we investigate the requirements for such an algorithm, evaluate the achievable closed loop bandwidth and the side effects on the overall-performance. In addition we apply the carrier tracking to simplify and automate the characterization of various electronic phase shifters and attenuators in the as-range  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB021  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB022 Sensitivity Analysis of Feedforward Beam Current Compensation for Improved Beam Loading Robustness 3850
 
  • D. Mihailescu Stoica, D. Domont-Yankulova
    RMR, TU Darmstadt, Darmstadt, Germany
  • D. Domont-Yankulova, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H. Klingbeil, D.E.M. Lens
    GSI, Darmstadt, Germany
 
  The planned SIS100 heavy ion synchrotron at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany will possess twenty ferrite accelerating cavities in its final stage of extension. During the intended acceleration cycles, the cavities will encounter significant beam loading effects, which have to be handled by the control systems. As both the generator- and beam-current act on the same system input, a feedforward disturbance compensation can be a promising approach to improve beam qualities and suppress instabilities induced by the beam current. Particle tracking simulations, incorporating twenty ferrite cavities and their attached LLRF control systems, are performed to analyse the sensitivity of the beam quality with respect to errors in the feedforward beam current compensation. The main focus lies on the time after injection from a pre-accelerator, where most cavities in the SIS100 do not provide any gap voltage and thus are particularly sensitive to induced voltages by beam currents if the cavities are not or only partly short-circuited.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB022  
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB023 An MTCA.4 Based Position Feedback Application Using Laserinterferometers 3853
 
  • K.P. Przygoda, Ł. Butkowski, S. Pfeiffer, H. Schlarb, P. Wiljes
    DESY, Hamburg, Germany
 
  To perform experiments on the nanometer scale at high brilliant x-ray light sources, it is highly recommended to have the mechanical components of the experiment, like lenses, mirrors and samples, as stable as possible. Since these components need to move from nanometer up to millimeter range they cannot be stabilized by only using rigid structures. For that reason an active stabilization system with fast and precise sensors needs to be developed. Here a Laserinterferometer is used, which provides picometer resolution at several MHz sample rate. In this paper we will present a laboratory setup which consists of a 6-slot Micro Telecommunication Computing Architecture generation 4 (MTCA.4) crate with standard components such MicroTCA carrier hub (MCH), central processing unit (CPU), power supply (PS) and cooling unit (CU). The Interferometer application has been setup with Deutsches Elektronen-Synchrotron (DESY) advanced mezzanine card (DAMC-FMC20) data processing unit, DESY Field Programmable Gate Array (FPGA) mezzanine card (DFMC-UNIO) universal input and output extension and DESY rear transition module (DRTM-PZT4) piezo driver. The encoder signals given by the interferometer controller are processed within the FPGA and then forwarded to the piezo amplifier RTM-board. The signal processing application includes decoding the digital feedback signal, calculating the coordinate transform for specific experimental setups and closed-loop operation based on a proportional integral derivative (PID) controller. The first results of the laboratory setup are demonstrated and briefly discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB023  
About • paper received ※ 12 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB024 Piezo Controls For The European XFEL 3856
 
  • K.P. Przygoda, J. Branlard, Ł. Butkowski, M.K. Grecki, M. Hierholzer, M. Omet, H. Schlarb
    DESY, Hamburg, Germany
 
  The European X-Ray Free Electron Laser (E-XFEL) accelerator is a pulse machine. The typical time duration of a radio frequency (RF) pulse is about 1.3 ms. The RF power transmitted to the superconducting RF (SCRF) cavity as a set of successive pulses (10 Hz repetition rate), causes strong mechanical stresses inside the cavity. The mechanical deformations of the RF cavity are typically caused by the Lorentz force detuning (LFD). The cavity can be tuned to a 1.3 GHz resonance frequency during the RF pulse using fast piezo tuners. Since the E-XFEL will use around 800 cavities (each cavity with double piezos), a distributed architecture with multi-channel digital and analog control circuits seems to be essential. The most sought-after issue is high-voltage, high-current piezo driving circuit dedicated to multi-channel configuration. The driving electronics should allow a maximum piezo protection against any kind of failure. The careful automation of the piezo tuners control and its demonstration for the high gradient conditions a real challenge. The first demonstration of piezo controls applied for chosen RF stations of the E-XFEL linear accelerator (linac) are presented and obtained results are briefly discussed within this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB024  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB025 New MicroTCA Piezo Driver (PZT4) 3860
 
  • K.P. Przygoda, Ł. Butkowski, M. Fenner, M. Hierholzer, R. Rybaniec, H. Schlarb, Ch. Schmidt
    DESY, Hamburg, Germany
  • R. Rybaniec
    PSI, Villigen PSI, Switzerland
 
  In the paper we would like to present a new Micro Telecommunication Computing Architecture (MicroTCA) piezo driver (PZT4). The piezo driver module is capable of driving of 4 piezo actuators with high voltages up to 160 Vpp. It is also possible to measure cavity mechanical vibrations using 4 analog to digital converters (ADC) ported to the driver electronics. The new piezo driver can be supplied using internal 12 V payload power provided by the MicroTCA standard. For the applications that need more than 30 W of the input power, the external power supply module can be provided. In order to protect the piezo driver electronics against output short condition a dedicated supervision circuit is designed. The piezo driver module has been setup at Cryo Module Test Bench (CMTB) facility in Deutsches-Elektronen Synchrotron (DESY) as a part of the single cavity low-level radio frequency (LLRF) controls. The LLRF control system has been used to demonstrate the radio frequency (RF) field stabilization and cavity tuning capabilities for continuous (CW) and pulse modes of operation of 1.3 GHz superconducting resonant RF (SCRF) cavity. The preliminary results are demonstrated and briefly discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB025  
About • paper received ※ 08 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB026 A 300 mm Long Prototype Strip-Line Kicker for the Heps Injection System 3864
 
  • L. Wang, J. Chen, L. Huo, P. Liu, H. Shi, X.L. Shi, G. Wang, N. Wang
    IHEP, Beijing, People’s Republic of China
 
  In the High Energy Photon Source (HEPS), the dynamic aperture of machine is not large enough for off-axis injec-tion for its baseline 7BA lattice design. So, a group of superfast kickers with about 12 ns pulse bottom width are needed for on-axis swap out injection scheme. The design about a couple sets of 300 mm long strip-line kickers is presented. Five kickers as a module are placed in a stain-less steel vacuum vessel to solve the problem of longitu-dinal space restriction in injection area. So far, the proto-type development of strip-line kicker was completed. The results of time-domain reflectometer (TDR) test and high voltage pulse test show that the strip-line kicker can meet the requirement of the HEPS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB026  
About • paper received ※ 06 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB028 Redesign of the JavaFX Charts Library in View of Real-Time Visualisation of Scientific Data 3868
 
  • R.J. Steinhagen, H. Bräuning, A. Krimm, T. Milosic
    GSI, Darmstadt, Germany
 
  The accurate graphical representation of accelerator- or beam-based parameters is crucial for commissioning and operation in any modern accelerator. Charts are one of the most visible but at the same time often underappreciated accelerator control system components even though these are crucial for easing and improving a quick intuitive understanding of complex or large quantities of data, which in turn is used to efficiently control, troubleshoot or improve the accelerator performance. While the Java SDK and other third-party libraries provide some charting components, we found that these lack either functionality, performance, or are based on outdated complex APIs. Based on earlier GSI and CERN designs and careful analysis of missing functionalities, performance bottlenecks, and long-term maintenance risks for the necessary workarounds, we decided that it was worth to re-engineer a new scientific charting library that preserves the functionality of established other libraries while addressing the performance bottlenecks and APIs issues. The new library offers a wide variety of plot types common in the scientific community, a flexible plugin system to extend the functionality towards chart interactors as well as online parameter measurements commonly found in oscilloscopes. Tailored towards high performance, it achieves real-time update rates up to 25 Hz for data sets with a few 10k up to 5 million data points. The new API shields the complexity from and eases the library’s use by normal users, while still being modular and having explicitly open interfaces that allow more-inclined developers to modify, add or extend missing functionalities. This contribution provides a performance and functionality comparison with other existing Java-based charting libraries.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB028  
About • paper received ※ 15 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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THPRB030 Novel FPGA-based Instrumentation for Personnel Safety Systems in Particle Accelerator Facility 3872
 
  • S. Pioli, M. Belli, M.M. Beretta, B. Buonomo, P. Ciambrone, D.G.C. Di Giulio, O. Frasciello, A. Variola
    INFN/LNF, Frascati, Italy
  • P. Valente
    INFN-Roma, Roma, Italy
 
  Personnel safety system for particle accelerator facility involves different devices to monitor gates, shielding doors, dosimetry stations, search and emergency buttons. In order to achieve the proper reliability, fail-safe and fail-proof capabilities, these systems are developed compliant with safety standards (like the IEC-61508 on ’Functional Safety’, ANSI N43.1 ’Radiation Safety for the design and operation of Particle Accelerator’ and NCRP report 88) involving stable technologies like electro-mechnaical relays and, recently, PLC. As part of the Singularity project at Frascati National Laboratories of INFN, this work will report benchmark of a new FPGA-based system from the design to the validation phase of the prototype currently operating as personnel safety system at the Beam Test Facility (BTF) of Dafne facility. This novel instrument is capable of: devices monitoring in real-time at 1 kHz, dual modular redundancy, fail-safe and fail-proof, multi-node distributed solution on optical link, radiation damage resistance and compliant with IEC-61508, ANSI N43.1 and NCRP report 88. The aim of this FPGA-based system is to illustrate the feasibility of FPGA technology in the field of personnel safety for particle accelerator in order to take advantage of a fully digital system integrated with facility control system, evaluate the related reliability and availability and realize a standard, scalable and flexible hardware solution also for other fields with similar requirements like machine protection systems.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB030  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB031 Operational Performance of the Machine Protection Systems of the Large Hadron Collider During Run 2 and Lessons Learnt for the LIU/HL-LHC Era 3875
 
  • M. Zerlauth, A. Antoine, W. Bartmann, C. Bracco, E. Carlier, Z. Charifoulline, R. Denz, B. Goddard, A. Lechner, N. Magnin, C. Martin, R. Mompo, S. Redaelli, I. Romera, B. Salvachua, R. Schmidt, J.A. Uythoven, A.P. Verweij, J. Wenninger, C. Wiesner, D. Wollmann, C. Zamantzas
    CERN, Geneva, Switzerland
 
  The Large Hadron Collider (LHC) has successfully completed its second operational run of four years length in December 2018. Operation will be stopped during two years for maintenance and upgrades. To allow for the successful completion of the diverse physics program at 6.5 TeV, the LHC has been routinely operating with stored beam energies close to 300 MJ per beam during high intensity proton runs as well as being frequently reconfigured to allow for special physic runs and important machine developments. No significant damage has incurred to the protected accelerator equipment throughout the run thanks to the excellent performance of the various machine protection systems, however a number of important observations and new failure scenarios have been identified, which were studied experimentally as well as through detailed simulations. In this contribution, we provide an overview of the performance of the machine protection systems throughout Run 2 as well as the important lessons learnt that will impact consolidation actions and the upgrade of the machine protection systems for the LIU/HL-LHC era.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB031  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB033 Development Status of RF Reference Phase Stabilization System for SuperKEKB Injector LINAC 3879
 
  • N. Liu, B. Dupresenter
    Sokendai - Hayama, Hayama, Japan
  • D.A. Arakawa, H. Katagiri, T. Kobayashi, T. Matsumoto, S. Michizono, T. Miura, F. Qiu, Y. Yano
    KEK, Ibaraki, Japan
  • T. Matsumoto, T. Miura, F. Qiu
    Sokendai, Ibaraki, Japan
 
  SuperKEKB injector linear accelerator (LINAC) has 600 m beam lines which consist of 8 sectors. The 2856 MHz RF reference signals are distributed to each sector with long phase stabilized optical fiber (PSOF). The RF reference phase stability requirement is estimated to be 0.2°(RMS) corresponding to 200 fs. The prototype of RF reference phase stabilization system with single mode optical circulator was implemented and demonstrated in the laboratory. The returned phase drift is compensated by a piezo-driven fiber stretcher. The transmitted phase through 120 m PSOF is stabilized to 41 fs (pk-pk), which fulfilled the requirement. This paper introduces the RF reference phase stabilization system and reports the preliminary feedback result.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB033  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB034 Timing Synchronization System for Beam Injection from the SACLA Linac to the SPring-8 Storage Ring 3882
 
  • T. Ohshima, N. Hosoda, S. Matsubara
    JASRI, Hyogo, Japan
  • N. Hosoda, H. Maesaka, T. Ohshima
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
 
  We developed a timing synchronization system for beam injections from the linac of the X-ray free-electron laser (XFEL), SACLA, to the current SPring-8 storage ring. This injection scheme is beneficial for the next upgraded ring, SPring-8-II, where low emittance injection beams is required. The developed timing system aims at synchronizing the timing between the RF frequencies of the two accelerators which do not have a common subharmonic frequency. An important point is to keep the high performance of the current timing system which provides stable XFEL operation at SACLA. For this purpose, we designed and constructed a MicroTCA.4 system comprised of a high-speed ADC and an RF front-end for the synchronization. The RF signal of SACLA is digitized by the ADC whose clock is synchronized to SPring-8. A digital down-converter in the FPGA on the ADC module gives the phase difference instantaneously and a feedback logic applies a frequency modulation (FM) to the master oscillator of SACLA so as to synchronize SACLA with SPring-8. A bench test result showed that the timing jitter between the two frequency at injection timing was 1.2 ps rms, which was sufficient for the required value of 3 ps rms for the beam injection to the ring. In this presentation, we report an overview of the synchronization system, details of the developed electronics and the system performance obtained by a beam injection experiment from SACLA to SPring-8.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB034  
About • paper received ※ 30 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB035 Development of Beam Window Protection System for J-PARC Linac 3886
 
  • H. Takahashi, S. Hatakeyama, Y. Sawabe
    JAEA/J-PARC, Tokai-mura, Japan
  • T. Ishiyama, T. Suzuki
    Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
  • T. Miyao
    KEK, Ibaraki, Japan
 
  In J-PARC Linac, beam study (including beam conditioning) is mainly performed using beam dump. A beam window is installed in the beam line to each beam dump. It is considered that the parameters of acceptable beam to able to be injected the beam window are the 50 mA current, the 100 micro-sec width and the 2.5 Hz repetition. On the other hand, at beam study of Linac, the beam with higher power than these parameters are not used. Therefore, the beam study was started and performed only after the operator checked that the beam parameters are within the acceptable values. However, at the beam study of 2018, a beam windows of 0-degree dump was cracked because the beam that exceeds acceptable parameters was injected due to human error. Then, beam study using 0-degree dump was impossible at all. And, in order not to cause such accident again, we began to develop the beam window protection system. Moreover, as soon as possible, implementation of the system was required. Therefore, we designed and developed this system by improving it based on the particle management system which can measure all 25 Hz beam. We have developed a beam window protection system that monitors the beam current for each shot and accumulated beam current for a prescribed time and inhibits the beam by MPS when either value exceeds the threshold. Moreover, we succeeded in developing and implementing this system in a short time. This paper is described about development and function test of beam window protection system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB035  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB036 Development of Injection and Extraction Kickers for SuperKEKB Damping Ring 3890
 
  • M. Tawada, M. Kikuchi, Y. Sakamoto, H. Someya
    KEK, Ibaraki, Japan
  • K. Tenjin, A. Tokuchi
    Pulsed Power Japan Laboratory Ltd., Kusatsu-shi Shiga, Japan
 
  SuperKEKB is a double ring asymmetric collider to study the B meson physics, which is an upgrade project of KEKB. The 7 GeV electron (HER) and the 4 GeV positron ring (LER) collides at an interaction point. The positron beam produced by linac cannot meet the dynamic aperture restrictions of LER. Damping ring (DR) is required to reduce its injection emittance. Damping ring (DR) for SuperKEKB has two kicker magnets for the injection and the extraction, respectively. These kickers are required to meet the following specifications: (1) rise and fall time does not exceed 100 ns, (2) two bunches which are 96 ns apart must be kicked by single pulse, (3) the stability of peak current for the extraction kickers must be less than 0.1 %. Kicker magnets are designed as a conventional kicker with a ferrite core. The pulse shape is a double half sine for the two bunch injection. In order to achieve short rise time, a saturable inductance is used. The design and performance of kicker magnets and the power supplies are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB036  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB037 Improved Frequency Characteristics Using Multiple Stripline Kickers 3893
 
  • T. Toyama, A. Kobayashi, H. Kuboki, M. Okada
    KEK, Tokai, Ibaraki, Japan
 
  One of the important ingredient in the intra-bunch transverse feedback is a kicker. The frequency characteristics of the kicker suffers from the transit-time factor, sin(kl)/kl. We examine the frequency characteristics of multiple kickers system. Relation between the excitation patterns of the multiple kickers and the frequency characteristics are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB037  
About • paper received ※ 23 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB038 ALARM SYSTEM OF IRFEL AT NSRL 3896
 
  • X. Chen, C. Li, G. Liu, Z.X. Shaopresenter, Y. Song, J.G. Wang, K. Xuan
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  An InfraRed Free Electron Laser Light (IRFEL) is under commissioning at National Synchrotron Radiation Laboratory (NSRL). The control system of IRFEL is a distributed system based on Experimental Physics and Industrial Control System (EPICS). The alarm system is an essential part of the control system. It is developed based on the software Phoebus. The module named "Alarms" in Phoebus can store states and configuration information of the Process Variable (PV) in the Kafka topics. To meet our requirements, 3 kinds of alarm message distribution applications are developed, i.e. Web-Based GUI, WeChat and SMS. This paper will introduce the alarm system architecture and the implementations of the applications for alarm message distribution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB038  
About • paper received ※ 17 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB041 Design a Precise Stability Controller for High Power Pulse Modulator Based on FPGA 3900
THPRB040   use link to see paper's listing under its alternate paper code  
 
  • Y.F. Liu, Z.H. Chen, M. Gupresenter, J. Tong, Y. Wu, Q. Yuan, X.X. Zhou
    SINAP, Shanghai, People’s Republic of China
 
  Shanghai Soft X-ray Free Electron Laser (SXFEL) facility is under testing at Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences. The stability of RF system is one of the major factors to get great beam performance. It is mainly determined by klystron modulators power supply. The beam voltage of the LINAC klystron modulator, which is the pulsed power source of the RF amplifier, is directly affecting the RF amplitude and phase. This paper shows the suitable upgrade scheme of the modulator power supply and design considerations for the stability improvement of modulator power supply for Shanghai SXFEL. We present a real time feedback control system of LINAC pulse modulator to improve pulse to pulse amplitude stability. The feedback control system is based on the principle of embedded FPGA techniques. The control system consists of an embedded NIOS II processor, a High resolution ADC and an upper computer. The NIOS II processor manage on chip FIFO, ADC, IRQ, and Ethernet. The relevant experiments indicate that the feedback control strategy reaches required function. It is useful to improve the stability of existing modulator power supply.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB041  
About • paper received ※ 21 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB042 Stability Research Progress on High-power Pulse Modulator for SXFEL-UF 3904
 
  • Q. Yuan, M. Gupresenter, Y.F. Liu, J. Tong, Y. Wu
    SINAP, Shanghai, People’s Republic of China
 
  Funding: Supported by the National Natural Science Foundation of China(11675250)
Abstract: SXFEL-UF(Shanghai Soft X-ray Free Electron Laser User Facility) under construction presently demands higher energy stability. Stability of pulse modulator feeding power for klystron plays an utmost important role in energy stability and occupy dominant factors in bringing influences in stability of RF power. Presently, stability of high-power pulse modulator of LINAC (Linear Accelerator) is on the level of 0.1% to 0.05% usually. In order to meet the higher stability requirements, it is very necessary for close-loop feedback control techniques instead of traditional open-loop to be applied in the modulator design. The stability controller adopts double control-loops techniques which feedback signals are respectively from PFN(Pulse Forming Network) and pulse transformer in oil tank. In addition, the paper also introduces recent progress on high stability CCPS research(Capacitor Charging Power Supply), which brings direct impact on the stability of modulator. In comparison with the former close-loop design, high stability CCPS design takes the overall modulator stability into full consideration. And the feedback control algorithm utilized to adjust PWMs for full bridge switch is implemented in the CCPS controller directly rather than modulator controller independent of CCPS. It is expected to obtain 0.01% stability by taking the above measures.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB042  
About • paper received ※ 06 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB043 Design and Simulation of Thin Eddy-Current Septum for Injection of Diffraction Limited Storage Ring 3908
 
  • J. Tong, M. Gupresenter, B. Liu, Y.F. Liu, R. Wang
    SINAP, Shanghai, People’s Republic of China
 
  Funding: Work supported by the National Key Research and Development Program of China(Grant No.2016YFA0402002)
Ultra-low emittance in Diffraction Limited Storage Ring (DLSR) usually has small Dynamic Aperture (DA), which makes the traditional off-axis injection inadequate. Fast kickers together with thin septum magnets or direct current lambertsons could support on-axis injection for closely-spaced bunches with small DA. Thin eddy-current septum prototype had been designed for injection with laminated silicon steel sheets as magnet core. Theoretical analysis and transient simulation had been carried out within OPERA software. Due to the minimum thickness of the septa is only 1 mm , several optimization approaches had been applied, such as shielding with strongly paramagnetic material and exciting with full cycle driving pulse, to satisfy the requirement that the leakage field is less than 0.1% with respect to the main one.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB043  
About • paper received ※ 29 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB044 LLRF Control System for RF GUN at SXFEL Test Facility 3912
 
  • L. Li, Q. Gu, Y.J. Liu, C.C. Xiao, J.Q. Zhang
    SINAP, Shanghai, People’s Republic of China
  • Y.F. Liu, Z. Wangpresenter
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
 
  A Soft X-ray Free Electron Laser Test Facility (SXFEL-TF) based on normal conducting linear accelerator was constructed at the Shanghai Synchrotron Radiation Facility (SSRF) campus by a joint team of Shanghai Institute of Applied Physics and Tsinghua University. It consists of multiple Radio Frequency (RF) stations with standing wave cavity (RF Gun) and traveling wave accelerating structures working at different frequencies. Low Level Radio Frequency (LLRF) system is used to measure the RF field in the cavities or structures and correct the fluctuation in RF fields with pulse-to-pulse feedback controllers. This paper describes the hardware and architecture of the LLRF system for electromagnetic filed stabilization inside the radio frequency electron gun, in the SXFEL-TF. A complete control path has be presented, including RF front-end board, I/Q detector and feedback controller. Algorithms used to stabilize the RF field have been presented as well as the software environment used to provide remote access to the control device. Finally, the performance of the LLRF system that was realized in the beam commissioning is presented and meets the high accuracy requirements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB044  
About • paper received ※ 23 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB045 A Novel Microwave Switch-Based LLRF System for Long-Term System Phase Drift Calibration 3915
 
  • Z.Y. Lin, Y.-C. Du, W.-H. Huang, C.-X. Tang, J. Tang
    TUB, Beijing, People’s Republic of China
  • G. Huang, Y.L. Xu
    LBNL, Berkeley, California, USA
  • Z. Sun, D. Zhang
    HZCY Technologies Co., Ltd., Beijing, People’s Republic of China
 
  The long-term phase drift is one of the important issue for the stability of the Low level RF system. The signal crosstalk and temperature effect on the RF field detectors will significantly limited the performance of the phase detecting precise and the phase locking. A novel micro-wave switch-based LLRF system has been developed in Tsinghua accelerator lab. The microwave switch are ap-plied to in the chopper circuit to turn continuous signal into pulse signal in the time domain to avoid the mutual signal interference. In this paper the LLRF system based on microwave switch is present. The preliminary long-term experiments result shows the phase stability can achieve about 50fs RMS slow drift; and the peak-to-peak value of the slow drift was (~2°C p-p) over 4 days.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB045  
About • paper received ※ 22 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB046 The Preliminary Long-Term Slow Drift Calibration Study in Low-Level Rf System 3918
 
  • Z.Y. Lin, Y.-C. Du, W.-H. Huang, C.-X. Tang, J. Tang
    TUB, Beijing, People’s Republic of China
  • G. Huang, Y.L. Xu
    LBNL, Berkeley, California, USA
  • Z. Sun, D. Zhang
    HZCY Technologies Co., Ltd., Beijing, People’s Republic of China
 
  The phase drift of the RF signal in the low-level radio frequency (LLRF) system is observed in the long-term operation, which limits the performance and stability of the LLRF system. The long-term drift was reproduced in the lab. Its effect and sources of error were explored in the simple LLRF46 board and the simplest LLRF system. It is founded that the temperature will significantly lead to the phase distortion of the two signal channels, although with the same electron device. The distortion will finally cause the long-term drift with temperature floating. A fixed phase calibration signal (CAL signal) is applied to deal with the signal channels difference. The preliminary tests were conducted and the results were analysed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB046  
About • paper received ※ 22 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB049 MODELING AND SIMULATION FOR MULTI-FEEDING CAVITY WITHOUT BEAM LOADING 3921
 
  • K. Liu, Q. Gu, L. Li, Ch. Wang, M.H. Zhaopresenter
    SINAP, Shanghai, People’s Republic of China
  • Q. Gu
    SSRF, Shanghai, People’s Republic of China
 
  The Multi-feeding cavity usually be applied in super-conducting and normal-conducting RF cavity. The differences between multiple input couplers in coupler coefficient, incident power and phase will cause the cavity field stabilities can not meet the requirements. For explore the influences of these differences and develop equations for measurement, a multi-feeding LCR transient model was developed. As two-feeding cavity, the VHF photocathode electron gun was model and simulated in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB049  
About • paper received ※ 06 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB050 LLRF System Modelling and Controller Design in UED 3924
 
  • Y.Q. Li, K. Fan, Y. Songpresenter
    HUST, Wuhan, People’s Republic of China
 
  In the Ultrafast Electron Diffraction (UED) facility for investigating material structure, drifts of amplitude and phase in cavity have different effects on beam quality. So it is critical for pump-probe experiments in the UED to keep accurate synchronization between the laser and electron. To achieve the desired 50fs resolution, the Low Level Radio Frequency (LLRF) controller in S-band normal conducting cavity needs to satisfy the stability: ±0.01% (rms) for the amplitude and ±0.01° (rms) for the phase, respectively. Then we can study the performance of the RF control system by simulating the LLRF system. In the simulation program, feedback, feed-forward algorithms, and beam current variations can be simulated in a Matlab/Simulink environment. This paper shows that a model-based controller design can meet the necessary requirements of the field regulation and implement the algorithms.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB050  
About • paper received ※ 20 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB053 Upgrade of the Historical Data Query and Analysis System for HLS-II 3928
 
  • Z.Y. Xie, C. Li, G. Liu, Z.X. Shaopresenter, Y. Song, J.G. Wang, K. Xuan
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  The current historical data query and analysis system for the Hefei Light Source II (HLS-II) was developed with Apache Struts2. However, Apache Struts2 need to be fixed from time to time to avoid being attacked. Therefore, a new system based on Spring Boot and Vue.js is developed. Meanwhile, the performance of the system is optimized, and the radiation monitor module is added. This paper will detail the system architecture and software implementation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB053  
About • paper received ※ 24 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB054 Design of a Ultrafast Stripline Kicker for Bunch-by-Bunch Feedback 3931
 
  • J. Wang, P. Li, D. Wu, D.X. Xiao, L.G. Yan
    CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
 
  Lorentz force detuning and beam loading effect of the rf cavities will induce a slope of the cavity gradient. Combed with the cavity misalignments, transverse position of subsequent bunches will differ from each other. The CAEP THz Free Electron Laser facility(CTFEL) will have a fast transverse bunch-by-bunch feedback system on its test beamline, which is used to correct the beam position differences of individual bunches in the macro-pulses. The time response of the kicker is rigid for the interval of the micro-pulses is 18.5ns and will upgrade to about 2 ns, requiring impedance matching of the kicker with the power source and transmission system in a high bandwidth. Also, the electromagnetic field must reach the requirements of the beam parameters. In this paper, the structure design and the optimization of the geometric parameters of the ultrafast stripline kicker is presented. The characteristic impedance, transmission characteristics, field consistency are analyzed and optimized. And the feedback signal generation scheme for continuous bunch trains was proposed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB054  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB055 DAMAGE BEHAVIOR OF TUNGSTEN TARGETS FOR 6 MEV LINEAR ACCELERATORS 3934
 
  • Z.H. Wang, Z.N. Liupresenter, J. Shi, H. Zha
    TUB, Beijing, People’s Republic of China
 
  The target in electron linear accelerator is subjected to high-frequency and intense thermal shocks. Elevated temperatures in the target may lead to target recrystallization, fatigue cracking, creep and vaporization. In this study, experiments were carried out to investigate the damage behaviour of tungsten targets in 6 MeV linear accelerators under pulsed electron beam. The results show that recrystallization occurs after loading 6 MeV electron beam with repetition frequency of 220 Hz, pulse width of 4μs and mean current of 151μA for 248 s. Deformation and cracking caused by recrystallization are observed on the surface of the target.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB055  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB056 Dose Measurement Experiments for Single and Composite Targets in 6 Mev Linear Accelerators 3937
 
  • Z.H. Wang, J.Y. Liupresenter, J. Shi, H. Zha
    TUB, Beijing, People’s Republic of China
 
  The target in electron linear accelerator plays an im-portant role in the production of photon. Targets of different materials and thicknesses have different X-ray yields. In this study, experiments were carried out to measure the dose rates of single targets and composite targets of different thicknesses for 6 MeV linear accel-erators utilizing ionization chamber. The electron ener-gy spectrum at the outlet of accelerating tube was de-tected with magnetic analyser. The experimental results show consistent rules with Monte Carlo simulations. Composite material target of 1.2 mm tungsten and 2 mm copper can deliver 1242 rad/min/100uA dose rate at 1 meter in front of the target. Dose rates of tungsten- rhenium alloy(74%W-26%rhenium) targets were exam-ined too.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB056  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB059 Radiation Safety at SOLARIS 1.5 GeV Storage Ring 3940
 
  • M.B. Jaglarz
    SOLARIS, Kraków, Poland
  • A.I. Wawrzyniak, J. Wikłacz
    Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
 
  Radiation measurements at Solaris are continuously performed by using 9 radiation monitor stations (RMS) located around the storage ring and the beamlines area. 4 of RMS are connected to the Personal Safety System and in case of exceeding alarm level dump the beam or close safety shutters. Moreover thermoluminescence dosimeters (TLDs) are used to registered doses in the classified areas according to the Polish regulation. Measurements are performed since 2015 when the commissioning of the storage ring has started. Since that time several improvements to the radiation shielding was done to fulfill the ALARA principle. Moreover the electron beam optimizations during the injection, ramping and operation were performed to decrease the electrons losses and the radiation level. This presentation will report on radiation measurements results obtained before and after the chopper installation. Additionally problems with radiation level while the beam current is increasing to the designed 500mA value will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB059  
About • paper received ※ 26 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB062 New Orbit Correction Method Based on SVDC Algorithm for Ring Based Light Sources 3943
 
  • X.Y. Huang, J.S. Cao, Y.Y. Du, Y.H. Lu, H.Z. Ma, Y.F. Ma, Y.F. Sui, S.J. Wei, Y. Wei, Q. Ye, X.E. Zhang, D.C. Zhu
    IHEP, Beijing, People’s Republic of China
 
  Funding: Union Foundation of excellent post-doctoral of China
Orbit feedback system is essential for realizing the exceeding beam stability in modern ring based light sources. Most advanced light sources adopt the global correction scheme by using singular value decomposition (SVD) algorithm. In this paper, a new SVD with constraints method (SVDC) is proposed to correct the global and local orbit simultaneously. Numerical simulations are presented with the case of High Energy Light Source (HEPS) by comparing classic algorithms. The results show that SVDC is very effective for orbit correction and very easy to implement.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB062  
About • paper received ※ 09 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB063 Field Control Challenges for Different LINAC Types 3946
SUSPFO095   use link to see paper's listing under its alternate paper code  
 
  • O. Troeng, A.J. Johansson
    Lund University, Lund, Sweden
  • M. Eshraqi
    ESS, Lund, Sweden
  • S. Pfeiffer
    DESY, Hamburg, Germany
 
  Linacs for free-electron lasers typically require cavity field stabilities of 0.01\% and 0.01 degree, while the requirements for high-intensity proton linacs are on the order of 0.1–1\% and 0.1–1 degrees. From these numbers it is easy to believe that the field control problem for proton linacs is many times easier than for free-electron lasers linacs. In this contribution we explain why this is not necessarily the case, and discuss the factors that make field control challenging. We also discuss the drivers for field stability, and how high-level decisions on the linac design affect the difficulty of the field control problem.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB063  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB066 Beam Based Measurements of Relative RF Phase 3950
 
  • S.C.P. Albright
    CERN, Geneva, Switzerland
  • M.D. Kuczynski
    LPCT, Vandoeuvre-lès-Nancy Cedex, France
 
  The ferrite loaded RF cavities of the CERN Proton Synchrotron Booster will be replaced with FinemetTM loaded cavities during Long Shutdown 2 2019-2020). To fully realise the potential of the new cavities, the relative RF phases must be aligned along the acceleration ramp, where the revolution frequency changes by nearly a factor of 2. A beam based method of measuring the relative phase between the cavities is desired to give the best possible compensation for the frequency dependent phase shift. In this paper we present an operationally viable method to measure the phase shift as a function of RF frequency. The relative phase of the RF cavities can be aligned to within a few degrees, giving an error on the voltage seen by the beam of less than 1%.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB066  
About • paper received ※ 08 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB067 Time Varying RF Phase Noise for Longitudinal Emittance Blow-Up 3954
 
  • S.C.P. Albright
    CERN, Geneva, Switzerland
  • D. Quartullo
    Sapienza University of Rome, Rome, Italy
 
  RF phase noise was shown to be effective for controlled longitudinal emittance blow-up in the Proton Synchrotron Booster (PSB) at CERN during beam tests in 2017, with further developments in 2018. At CERN, RF phase noise is used operationally in the Super Proton Synchrotron (SPS) and Large Hadron Collider (LHC). In this paper we show that it is suitable for operation with a variety of beam types in the PSB. In the PSB the synchrotron frequency changes by approximately a factor 4 during the 500 ms acceleration ramp, requiring large changes in the frequency band of the noise. During 2018, a new method of calculating the noise parameters has been demonstrated, which gives upper and lower bounds to the noise frequency band that are smoothly varying through the ramp. The new calculation method has been applied to operational beams accelerated in both single and double RF harmonics, the final results are presented here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB067  
About • paper received ※ 29 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB068 Upgrade of CERN’s PSB Digital Low-Level RF System 3958
 
  • M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Jaussi, J.C. Molendijk, N. Pittet
    CERN, Geneva, Switzerland
 
  The CERN PS Booster (PSB) is the first circular accelerator in the LHC proton injector chain. The upgrade of this four-ring machine is underway within the framework of the LHC Injectors Upgrade project. The existing digital Low-Level RF (LLRF) system will also be upgraded. This paper outlines the LLRF capabilities required, their implementation and the challenges involved. Results of tests carried out to prepare for the LLRF upgrade are given.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB068  
About • paper received ※ 13 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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THPRB069 The New Digital Low-Level RF System for CERN’s Extra Low Energy Antiproton Machine 3962
 
  • M.E. Angoletta, M. Jaussi, J.C. Molendijk
    CERN, Geneva, Switzerland
 
  CERN’s new Extra Low ENergy Antiproton accelerator/decelerator (ELENA) completed its initial commissioning in 2018. This machine is equipped with a new digital Low-Level RF (LLRF) system that implements beam and cavity loops as well as longitudinal diagnostics. ELENA’s LLRF was instrumental for machine commissioning by decelerating some 1 E7 antiprotons from 5.3 MeV to 100 keV. Commissioning with H ions took also place. Challenges faced included coping with low beam intensity and the wide frequency swing. This paper gives an overview of the LLRF system capabilities and operation. Beam results achieved with both H ions and antiprotons are also shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB069  
About • paper received ※ 13 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB070 A New Digital Low-Level RF and Longitudinal Diagnostic System for CERN’s AD 3966
 
  • M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Jaussi, J.C. Molendijk, V. R. Myklebust
    CERN, Geneva, Switzerland
 
  The Antiproton Decelerator (AD) has been routinely providing 3 E7 antiprotons since July 2000 at 100 MeV/c from 3.5 GeV/c. It will be refurbished during the Long Shutdown 2 (LS2) to provide reliable operation for the new Extra Low ENergy Antiproton (ELENA) ring. AD will be equipped with a new digital Low-Level RF (LLRF) system before its restart in 2021. Diagnostics to measure beam intensity, Δp/p and Schottky spectra will also be developed. This paper is an overview of the planned capabilities and implementations, as well as of the challenges to overcome.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB070  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB071 Beam-Based Measurements on Two ±12.5 kV Inductive Adders, together with Striplines, for CLIC Damping Ring Extraction Kickers 3970
 
  • J. Holma, M.J. Barnes, M. Carlàpresenter, N. Catalán Lasheras, Y. Papaphilippou
    CERN, Geneva, Switzerland
  • U. Iriso, Z. Martí, F. Pérez, M. Pont
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
 
  The CLIC study is investigating the technical feasibil-ity of an electron-positron linear collider with high lumi-nosity and a nominal centre-of-mass energy of 3 TeV. Pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. The DR kicker systems, each of which consists of a set of striplines and two inductive adders, must provide ex-tremely stable field pulses. The DR extraction kicker system is the most demanding: specifications require a field uniformity within ±0.01% and pulses up to 900 ns flattop duration, at ±12.5 kV and 309 A, with ripple and droop of not more than ±0.02 % (±2.5 V), with respect to a reference waveform. Two prototype inductive adders have been designed and built at CERN, and have been tested with prototype striplines installed in the storage ring of the ALBA Synchrotron Light Source, in Spain. The stability of the kicker system, including the modulators, has been evaluated from the beam-based measure-ments and is reported in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB071  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB072 Operational Experience of a Prototype LHC Injection Kicker Magnet with a Low SEY Coating and Redistributed Power Deposition 3974
 
  • M.J. Barnes, C. Bracco, G. Bregliozzi, A. Chmielinskapresenter, L. Ducimetière, B. Goddard, G. Iadarola, T. Kramer, V. Vlachodimitropoulos, W.J.M. Weterings
    CERN, Geneva, Switzerland
  • A. Chmielinskapresenter
    EPFL, Lausanne, Switzerland
  • L. Vega Cid
    ETSII UPM, Madrid, Spain
 
  Funding: This research was supported by the HL-LHC project
In the event that it is necessary to exchange an LHC injection kicker magnet (MKI), the newly installed kicker magnet would limit HL-LHC operation for a few hundred hours due to dynamic vacuum activity. A surface coating with a low secondary electron yield, applied to the inner surface of an alumina tube to reduce dynamic vacuum activity without increasing the probability of UFOs, and which is compatible with the high voltage environment, was included in a prototype MKI installed in the LHC during the 2017-18 Year End Technical Stop. In addition, this MKI included an upgrade to relocate a significant portion of beam induced power from the yoke to a ’damping element’: this element is not at pulsed high voltage. The effectiveness of the upgrades has been demonstrated during LHC operation, hence a future version will include water cooling of this ’damping element’. This paper reviews dynamic vacuum around the MKIs and summarizes operational experience of the upgraded MKI.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB072  
About • paper received ※ 08 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB073 Laboratory Measurements on Two ±12.5 kV Inductive Adders with ±0.02% Waveform Stability for CLIC Damping Ring Extraction Kickers 3978
 
  • J. Holma, M.J. Barnes, A. Chmielinskapresenter
    CERN, Geneva, Switzerland
  • M. Pont
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
 
  The CLIC study is investigating the technical feasibil-ity of an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. Pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. The DR kicker systems must provide extremely stable field pulses to avoid beam emittance increase. Each DR extrac-tion kicker system consists of a set of striplines and two pulse modulators. Specifications for this system require that the modulator produce pulses of 900 ns flattop dura-tion, ±12.5 kV and 305 A, with ripple and droop of not more than ±0.02 % (±2.5 V) with respect to a reference waveform. Inductive adder topology has been chosen for the pulse modulators. Two full-scale, 20-layer, 12.5 kV prototype inductive adders have been designed, built and tested at CERN. This paper presents the measurements of the stability of these adders for two different waveforms: a flat-top waveform and a controlled decay waveform, the latter of which is required to generate flat-top total field for the CLIC DR extraction stripline kicker.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB073  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB074 Studies Towards the New Beam Screen System of the LHC Injection Kicker Magnet for HL-LHC Operation 3982
 
  • V. Vlachodimitropoulos, M.J. Barnes, A. Chmielinskapresenter, L. Ducimetière, L. Vega Cid, W.J.M. Weterings
    CERN, Geneva, Switzerland
  • A. Chmielinskapresenter
    EPFL, Lausanne, Switzerland
  • L. Vega Cid
    ETSII UPM, Madrid, Spain
 
  Although no heating issues were observed in the Large Hadron Collider’s (LHC) injection kicker magnets (MKIs) during Run 2, simulations suggest that for operation with the high intensity beams of the High Luminosity LHC (HL-LHC) project, the magnet’s ferrite yokes will reach their Curie temperature, thus leading to long turnaround times before a new beam can be safely injected into the machine. To safely enter the HL-LHC era, a campaign to redesign the kicker’s beam screen was launched. An improved beam-screen has already been implemented in an upgraded MKI, that was installed in the LHC tunnel in the Year End Technical Stop (YETS) 17/18, and has been successfully tested during 2018 operation. However, the improved design alone is not expected to be enough for HL-LHC operation, and further modifications are required. In this work, the approach to the design from an electromagnetic point of view is presented and different considered options are reported, emphasising the final design of the new beam screen system that is currently being implemented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB074  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB075 Transverse Impedance Measurements and Simulations of the LHC Injection Kicker Magnet 3986
 
  • V. Vlachodimitropoulos, M.J. Barnes, A. Chmielinskapresenter, L. Ducimetière
    CERN, Geneva, Switzerland
  • A. Chmielinskapresenter
    EPFL, Lausanne, Switzerland
 
  Kicker magnets contribute significantly to the total impedance budget of many accelerators. Of particular interest, from a beam stability point of view, is the transverse beam coupling impedance (TBCI) that is used to determine intensity limitations of a machine. Until recently, no conclusive TBCI data for the Large Hadron Collider (LHC) injection kicker magnets (MKIs) was available. However, in view of the upgrade of the MKIs for the High-Luminosity LHC (HL-LHC) project, the TBCI of the existing design needed to be estimated to be used as reference for an upgraded version. To that end, electromagnetic simulations were carried out to determine the dipolar and quadrupolar components of the TBCI in the two transverse planes. To validate the simulations, test bench measurements were performed using standard RF measurement techniques. In the present work, the results from TBCI simulations and measurements are reported and compared. Detailed descriptions of the methods and techniques used as well as the realization of the experimental set-up are also given.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB075  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB077 Optics Corrections Using Machine Learning in the LHC 3990
 
  • E. Fol, J.M. Coello de Portugal, R. Tomás
    CERN, Meyrin, Switzerland
  • G. Franchetti
    GSI, Darmstadt, Germany
 
  Optics corrections in the LHC are based on a response matrix approach between available correctors and observables. Supervised learning has been applied to quadrupole error prediction at the LHC giving promising results in simulations and surpassing the performance of the traditional approach. A comparison of different algorithms is given and it is followed by the presentation of further possible concepts to obtain optics corrections using machine learning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB077  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB078 Performance Validation of the Existing and Upgraded PS Injection Kicker 3994
 
  • A. Ferrero Colomo, N. Ayala, A. Chmielinskapresenter, V. Forte, M.A. Fraser, T. Kramer, L. Sermeus
    CERN, Geneva, Switzerland
 
  The CERN PS injection kicker KFA45 will be upgraded in the framework of the LHC Injector Upgrade (LIU) project to allow for injection of 2 GeV proton beams. This paper summarizes the recent efforts to validate beam based waveform measurements, Pspice simulations and current waveform measurements by direct magnetic field measurements in the aperture of the existing system. The magnetic probe, associated measurement hardware design and measurements results are discussed. The paper concludes with a performance comparison and an outlook to future waveform tuning possibilities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB078  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB079 DC Testing and Phase Resolved Partial Discharge Measurements of the New Trigger Transformers for the LHC Beam Dump Kickers 3998
 
  • T. Stadlbauer, A. Chmielinskapresenter, L. Ducimetière, D. Kontelis, T. Kramer, V. Senaj
    CERN, Geneva, Switzerland
 
  During LS2 the LHC beam dump kicker pulse generators will be subject to a substantial consolidation program. One major part is the replacement of the existing GTO stack trigger transformer by a new more performant one. The transformer is assembled, moulded and tested in-house. Part of the validation procedure are standard DC tests and subsequent discharge monitoring as well as newly introduced phase resolved partial discharge measurements. This paper briefly highlights the trigger transformer parameters and construction and outlines in detail the testing and partial discharge measurements. It concludes with a comparison and analysis of the results of the different measurement techniques.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB079  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB080 Automatisation of the SPS ElectroStatic Septa Alignment 4001
 
  • S. Hirlaender
    ATI, Vienna, Austria
  • M.A. Fraser, B. Goddardpresenter, V. Kain, J. Prieto, L.S. Stoel, F.M. Velotti
    CERN, Geneva, Switzerland
  • M. Szakaly
    Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary
 
  An electrostatic septum composed of 5 separate tanks is used to slow-extract the 400 GeV proton beam resonantly on the third integer resonance from the CERN SPS. The septa are all mounted on a single support structure that can move the ensemble coherently and, in addition, the internal anode and cathode of each tank can be moved independently. The septum is aligned to the beam by measuring and minimising the induced beam loss signals in the extraction region following an alignment procedure that is usually carried out manually at the beginning of each year. The large number of positional degrees of freedom complicates the procedure and until recently each tank was aligned one after the other semi-manually, typically requiring 8 hours. It is not uncommon that the septum has to be re-aligned later in the run taking time away from physics programme. To tackle this issue, a simplified beam dynamics and scattering simulation routine was developed to permit error studies with a large number of seeds to be carried out in a reasonable computation time. In this contribution, the simulation model will be described before the results of its exploitation to understand the efficacy of alignment procedures based on different optimization algorithms are discussed and compared to the present operational procedure. The effort culminated with the implementation of an automated alignment procedure based on a Powell optimisation algorithm that reduced the time needed to align the septum by over an order of magnitude.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB080  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB082 The CERN SPS Low Level RF upgrade Project 4005
 
  • G. Hagmann, P. Baudrenghien, J.D. Betz, J. Egli, G. Kotzian, M. Rizzi, L. Schmid, A. Spierer, T. Włostowski
    CERN, Meyrin, Switzerland
  • F.J. Galindo Guarch
    Universitat Politécnica de Catalunya, Barcelona, Spain
 
  The High Luminosity LHC project (HL-LHC) calls for the doubling of the beam intensity injected from the Super Proton Synchrotron (SPS). This is not possible with the present RF system consisting of four 200 MHz cavities. An upgrade was therefore launched, consisting of the installation of two more cavities during the machine shutdown in 2019-2020 (LS2). Installation of more cavities requires the installation of extra Low Level RF (LLRF) electronics. The present LLRF system consists of the original equipment installed in the 1970s, plus some additions dating from the late 1990s when the SPS was commissioned as LHC injector. The High-Power RF up-grade has motivated a complete renovation of the LLRF during LS2; use of a MicroTCA platform, use of a digital deterministic link for synchronization (the so-called White Rabbit), use of an absolute clock for the processing, new algorithms for reducing the cavity impedance, and a complete re-design of the beam control loops and slip-stacking.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB082  
About • paper received ※ 13 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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THPRB083 Detailed Analysis Of The Baseline Dose Levels And Localized Radiation Spikes In The Arc Sections Of The Large Hadron Collider During Run 2 4009
 
  • K. Bilko, M. Brugger, R. Garcia Alia, F.J. Hardenpresenter, Y. Kadi, O. Stein
    CERN, Geneva, Switzerland
 
  The Large Hadron Collider (LHC) has eight insertion regions (IRs) which house the large experiments or accelerator equipment. These IRs are interconnected with the arc sections consisting of a periodic magnet structure. During the operation of the LHC small amounts of the beam particles are lost, creating prompt radiation fields in the accelerator tunnels and the adjacent caverns. One of the main loss mechanisms in the LHC arc sections is the interaction of the beam particles with the residual gas molecules. The analysis of the dose levels based on the beam loss measurement data shows that the majority of the measurements have similar levels, which allow to define baseline values for each arc section. The baseline levels decreased during the years 2015, 2016 and stabilised in 2017 and 2018 at annual dose levels below 50 mGy, which can be correlated with the residual gas densities in the LHC arcs. In some location of the arcs radiation spikes exceed the base line by more than two orders of magnitude. In addition to the analysis of these dose levels, a novel approach of identifying local dose maxima and the main driving mechanisms creating these radiation spikes will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB083  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB084 Run 2 Prompt Dose Distribution and Evolution at the Large Hadron Collider and Implications for Future Accelerator Operation 4013
 
  • O. Stein, K. Bilko, M. Brugger, R. Garcia Alia, F.J. Hardenpresenter, Y. Kadi, A. Lechner, G. Lerner
    CERN, Geneva, Switzerland
 
  During the operation of the Large Hadron Collider (LHC) small fractions of beam particles are lost, creating prompt radiation fields in the accelerator tunnels. Exposed electronics and accelerator components show lifetime degradation and stochastic Single Event Effects (SEEs) which can lead to faults and downtime of the LHC. Close to the experiments the radiation levels scale nicely with the integrated luminosity since the luminosity debris is the major contributor for creating the radiation fields in this area of the LHC. In the collimation regions it was expected that the radiation fields scale with the integrated beam intensities since the beams are continuously cleaned from particles which exceed the accelerator’s acceptance. The analysis of radiation data shows that the dose measurements in the collimation regions normalised with the integrated beam intensities for 2016 and 2017 are comparable. Against expectations, the intensity normalised radiation datasets of 2018 in these regions differ significantly from the previous years. Especially in the betatron collimation region the radiation levels are up to a factor 3 higher. The radiation levels in the collimation regions correlate with the levelling of beta-star and the crossing angle in the high luminosity experiments ATLAS and CMS. These increased normalised doses have direct implications on the expected dose levels during future LHC operation, including the High-Luminosity LHC (HL-LHC) upgrade.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB084  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB085 HiRadMat: A Facility Beyond the Realms of Materials Testing 4016
 
  • F.J. Harden, A. Bouvard, N. Charitonidis, Y. Kadi
    CERN, Geneva, Switzerland
 
  The ever-expanding requirements of high-power targets and accelerator equipment has highlighted the need for facilities capable of accommodating experiments with a diverse range of objectives. HiRadMat, a High Radiation to Materials testing facility at CERN has, throughout operation, established itself as a global user facility capable of going beyond its initial design goals. Pulsed high energy, high intensity, proton beams have been delivered to experiments ranging from materials testing, detector’s prototype validation, radiation to electronics assessment and beam instrumentation. A 440 GeV/c proton beam is provided directly from the CERN SPS. Up to 288 bunches/pulse at a maximum pulse intensity of 3.5 x 1013 protons/pulse can be delivered. Through collaborative efforts, HiRadMat has developed into a state-of-the-art facility with improved in situ measurement routines, beam diagnostic systems and data acquisition techniques, offered to all users. This contribution summarises the recent experimental achievements, highlights previous facility enhancements and discusses potential future upgrades with particular focus on HiRadMat as a facility open to novel experiments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB085  
About • paper received ※ 29 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB086 Design & Optimization of the Alignment Supports for the New Laminated Magnets for the CERN East Area Consolidation Project 4020
 
  • R. Vanhoutte, D. Brethoux, A. Ebn Rahmoun, S. Evrard, F.J. Hardenpresenter, E. Harrouch, M. Lazzaroni, M. Lino Diogo dos Santos, R. Lopez, D.E. Nogtikov, J. Renedo Anglada
    CERN, Meyrin, Switzerland
 
  The East Area is one of CERNs experimental area, running since its foundation in 1958. Extracting a 24GeV proton beam from the Proton Synchrotron accelerator, the primary beam is divided into different secondary beams, serving various experiments and user’s facilities such as CLOUD, CHARM, IRRAD. Due to improved optics and an energy saving scheme, the facility will go under a renovation between 2019 and 2020, including the replacement of the magnets with new laminated ones to allow a cycled powering scheme. Those magnets need improved supports, and in some cases even a new design, to optimize the alignment operations in those areas. This article will mainly address the different proposed solutions for plug-in supports as well as for conventional ones.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB086  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB087 Study of the Energy Savings Resulting from the East Area Renovation 4023
 
  • B. LM. Lamaille, F. Dragoni, S. Evrard, F.J. Hardenpresenter, E. Harrouch, M. Lazzaroni, R. Lopez, K.D. Papastergiou
    CERN, Meyrin, Switzerland
 
  CERN’s East Experimental Area, situated on the Swiss side of the Meyrin site, with its four beamlines, has served physics for more than 40 years. As the building and equipment are reaching their end of life, a thorough consolidation project has been initiated in order to pro-vide many more years of reliable operation. This article addresses the different proposed solutions to reduce significantly the energy consumption of the East Area. It outlines the methodology applied to estimate as precisely as possible the future attained energy savings, which will result in an estimated reduction of approximately 80% in electricity usage (from 11 GWh to 2 GWh per year) and of approximately 65% in gas usage for heating purpose (from 3 GWh to 1 GWh per year).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB087  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB088 Optimizing The Reliability of The Fire Alarm System in The Taiwan Photon Source 4026
 
  • W.S. Chan, F.-D. Chang, C.S. Chen, Y.F. Chiu, J.C. Liu, Z.-D. Tsai
    NSRRC, Hsinchu, Taiwan
 
  The fire alarm system plays a critical role for the safety of building occupants. However, in the past two years from 2016 to 2017, occasionally false alarms at the Taiwan Photon Source (TPS) occurred. Results of more detailed observations indicated that radiation and/or electromagnetic interference (EMI) of the TPS accelerator disturb smoke detectors and signal line circuits (SLCs). Lead shielding covers, adjusting of the detector alarm verification time and a laser-based aspi-rating smoke detector were used to reduce the probabil-ity that fire alarms become activated to less than 0.5 times per year.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB088  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB090 Laboratory Exhaust Gas Treatment Systems at TPS 4029
 
  • J.-C. Chang, W.S. Chanpresenter, Z.-D. Tsai
    NSRRC, Hsinchu, Taiwan
 
  There are three main laboratory exhaust gas treatment systems equipped at Taiwan Photon Source (TPS): acid/alkaline system for corrosive acids and alkalis, volatile solvents, and other hazardous chemicals; organic system for biological experiments; and general system for other gas. Gas is collected in hoods installed near the sources of contamination in laboratories. The contamination then is transported through duct to the gas treatment equipment installed outside of the TPS experimental hall.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB090  
About • paper received ※ 06 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB091 APPLICATION PROGRAMS FOR TPS BEAM TRIP ANALYSIS 4032
 
  • B.Y. Chen, T.W. Hsu, B.Y. Huang, C.S. Huang, C.H. Kuo, T.Y. Leepresenter, W.Y. Lin
    NSRRC, Hsinchu, Taiwan
 
  For the Taiwan Photon Source (TPS), the orbit inter-lock system is one of the most important machine pro-tection systems. It is the fastest and the most preferred system to detect abnormalities to prevent possible dam-ages caused by magnet power supply failures or subsys-tems failures. In order to monitor electron orbit changes during a beam trip, we developed the ’orbit monitoring and recording tool’, the ’TBT BPM analysis tool’ and the ’magnet power supply recording and analysis tool’ to assist us in the failure analysis as will be discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB091  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB092 Reduction of Beam Induced RF-Heating in the Horizontal Stripline Kicker at the TPS 4035
 
  • P.J. Chou, C.K. Chan, C.-C. Chang, K.T. Hsu, K.H. Hu, C.K. Kuan, I.C. Sheng
    NSRRC, Hsinchu, Taiwan
 
  In preparation for 500 mA operation at the Taiwan Pho-ton Source (TPS), we redesigned the horizontal stripline kicker for the beam feedback system to gain a smaller loss factor with higher shunt impedance. We introduced ground fenders (see Fig. 1) to this new design which resulted in the reduction of the loss factor and substantial increase of the kicker shunt impedance. The transverse profile of the kicker electrodes was matched to the race-track beam pipe in the straight sections to minimize broadband impedance. The ground fenders can reduce the leakage of image currents through the gaps between the two strip line electrodes and also help to achieve a better impedance matching for the TEM modes in the transmission lines formed by the stripline electrodes and beam pipe in the kicker. The RF design and analysis of trapped resonant modes in the kicker were simulated by the 3-D electromagnetic code GdfidL [1]. Results of the RF design and analysis of trapped resonant modes will be discussed together with analytical estimates of coupled bunch instabilities at a beam current of 500 mA.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB092  
About • paper received ※ 17 April 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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THPRB093 RF Data Acquisition and Soft Alarm System for the Taiwan Photon Source 4039
 
  • Z.K. Liu, F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, Y.T. Li, M.-C. Lin, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
 
  The Taiwan Photon Source (TPS) is a modern, high brightness 3 GeV light source. A data acquisition pro-gram for the radio frequency (RF) system, including a transient data recorder, a long term data archiver and real time data monitoring, has been developed for the analysis of RF trips and RF system debugging. A soft alarm system is implemented as well utilizing EPICS and python packages. The hardware architecture and the functionality of the RF data acquisition and soft alarm system will be discussed in this article.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB093  
About • paper received ※ 09 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB094 Study of the System Stability for the Digital Low Level RF System Operated at High Beam Currents 4042
 
  • Z.K. Liu, F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, Y.T. Li, M.-C. Lin, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
 
  The purpose of a Low-Level Radio Frequency (LLRF) system is to control the amplitude and phase of the field in the accelerating cavity. A digital LLRF (DLLRF) system will be installed in the Taiwan Photon Source (TPS) storage ring in 2019. The system stability depends much on the feedback parameters. An instability of the cavity voltage controlled by a DLLRF was observed during machine tests with high beam current and low feedback gain. A simulation model for the digital LLRF system with beam-cavity interaction was developed to investigate this instability and simulations and machine test results will be presented here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB094  
About • paper received ※ 07 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB095 A Simulation Framework for Photon-Particle Interactions for Laserwires and Further Applications 4045
SUSPFO112   use link to see paper's listing under its alternate paper code  
 
  • S. E. Alden, S.M. Gibson, L.J. Nevay
    JAI, Egham, Surrey, United Kingdom
 
  A model has been developed for simulating photon-particle interactions with Beam Delivery Simulation (BDSIM). BDSIM is a high energy physics program that utilises the Geant4, CLHEP, and ROOT libraries to seamlessly track particles through an accelerator. The photon-particle interactions introduce the capability for modelling a range of applications in accelerator physics. One such application is a laserwire which is a minimally invasive diagnostic technique to measure beam profiles and emittance. In this paper we describe the recent implementation of inverse Compton scattering and electron stripping of Hydrogen ions. This is demonstrated on an example beamline.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB095  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB096 Real-Time Beam Orbit Stabilisation to 200 Nanometres in Single-Pass Mode Using a High-Precision Dual-Phase Feedback System 4049
 
  • D.R. Bett, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan
    JAI, Oxford, United Kingdom
 
  A high-resolution, low-latency, stripline beam position monitor (BPM) system has been developed for use at particle accelerators and beamlines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system consists of fast analogue stripline BPM signal processors input to a custom FPGA-based digital feedback board which drives a pair of kickers local to the BPMs and nominally orthogonal in phase in closed-loop feedback mode, thus achieving both beam position and angle stabilisation. The feedback system was tested with the electron beam in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan. Recent upgrades to the BPMs have increased the single-shot, real-time position resolution of the system to ~150 nm for a beam charge of 1.3 nC. We report the latest results which demonstrate the feedback system operating at this resolution limit and a beam stabilisation performance of 200 nm.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB096  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB097 Analysis of RF System Stability on CLARA 4053
 
  • N.Y. Joshi, J.K. Jones, A.J. Moss, E.W. Snedden, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • A.C. Dexter, J. Henderson
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • J.K. Jones
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  The Compact Linear Accelerator for Research and Applications (CLARA) facility at STFC Daresbury Laboratory will test underpinning concepts and technology for a next generation X-ray free electron laser (FEL). CLARA will use four S-band normal conducting traveling wave linacs to accelerate electron bunches to a maximum energy of 250 MeV. The amplitude and phase stability of the collected RF systems is critical in enabling CLARA to achieve low (10 fs) shot-to-shot timing jitter of the photon output. Here we present initial measurements and model of the amplitude and phase jitter of the CLARA RF systems, achieved by experimentally correlating the klystron output with controls from modulator, driver, and other environment parameters. The effect of the RF jitter on the CLARA beam momentum is also integrated in the model.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB097  
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB098 FETS Personnel & Machine Interlock Systems 4057
 
  • J.H. Macgregor
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  The Front End Test Stand (FETS) [1] is a high energy pulsed proton driver that aims to produce a perfectly chopped 50 Hz, 60 mA, 2 ms H’ beam. FETS consists of a Penning Ion source, Low Energy Beam Transport (LEBT), 4 m long bolted construction 324 MHz four vane Radio Frequency Quadrupole (RFQ). The H’ Beam will be perfectly chopped so that bunches of particles can be trapped and accelerated with very low loss into a circular accelerator. To protect personnel from X-ray radiation along with prompt neutrons & gamma radiation, a concrete block-house has been built around the facility and a personnel interlock and search system developed. This paper discusses the mechanical and electrical systems used to ensure personnel safety via the Personnel Protection System (PPS) and machine safety by use of a Programmable Logic Controller, (PLC), used as the Machine Interlock Systems.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB098  
About • paper received ※ 09 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB099 Applications of Dimension-Reduction to Various Accelerator Physics Problems 4060
 
  • W.F. Bergan, I.V. Bazarov, C.J.R. Duncan, D. L. Rubin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: DE-SC 0013571 DGE-1650441 OIA-1549132
Particle accelerators contain hundreds of magnets, making dimension-reduction techniques attractive when attempting to tune them. We apply this procedure to two different problems: correcting the orbit in the Cornell synchrotron and maximizing the dynamic aperture in the Cornell Electron Storage Ring (CESR). Cornell’s rapid cycling synchrotron accepts a 200 MeV beam from the linac and accelerates it to 6 GeV for injection into the CESR. ‘Kicker coils’ (dipole correctors) are used to correct for residual fields which would otherwise cause beam loss at the low energies. In such cases, it is usually advisable to measure and correct the orbit. However, one cannot measure the orbit without first getting the beam to circulate a few hundred times, by which point the low-energy orbit would already be mostly corrected. In order to speed up the process of empirical orbit tuning, we form knobs which have the largest effect on the global orbit error, so that the dimensionality of the space which must be searched may be greatly reduced. A small dynamic aperture in CESR will have adverse effects on beam lifetime and injection efficiency, and so ought to be maximized by tuning sextupoles. However, it is often unclear which sextupoles one ought to tune to alleviate the problem. Moreover, once the chromaticity is properly adjusted, it should not be changed. Since we expect resonance driving terms (RDTs) to have a large impact on the dynamic aperture, we develop sextupole knobs which change the RDTs as much as possible while leaving the chromaticity fixed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB099  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB100 A Generic Software Platform for Rapid Prototyping of Online Control Algorithms 4063
SUSPFO123   use link to see paper's listing under its alternate paper code  
 
  • C.J.R. Duncan, M.B. Andorf, I.V. Bazarov, I.V. Bazarov, C.M. Gulliford, V. Khachatryan, J.M. Maxson, D. L. Rubin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • I.V. Bazarov
    Cornell University, Ithaca, New York, USA
 
  Funding: US Department of Energy DE-SC 0013571
Algorithmic control of accelerators is an active area of research that promises significant improvements in machine performance. To facilitate rapid algorithm prototyping, we have developed a generic interface between accelerator controls, beam physics modelling software and modern scripting languages. The work-flow of a project using this interface begins with testing algorithms of choice offline in simulation. After off-line testing, the same code can be deployed on real machines via the Experimental Physics and Industrial Control System (EPICS) API. We include noise in our simulations in order to mimic realistic accelerator behaviour and to evaluate robustness of algorithms to experimental uncertainties and long-term drifts. The results of test cases of using this framework are presented, including emittance tuning of the Cornell Electron Storage Ring (CESR), correction of diurnal drift in CESR steering and orbit correction on CESR and the Cornell-BNL ERL Test Accelerator (CBETA).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB100  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB102 Monte Carlo Optimization of Fast Beam Loss Monitors for LCLS-II 4066
 
  • M. Santana-Leitner, C.I. Clarke, A.S. Fisher, A.M. Harris, C. Hast, T.T. Liang
    SLAC, Menlo Park, California, USA
  • E. Griesmayer
    CIVIDEC Instrumentation, Wien, Austria
 
  Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515
Commissioning of the LCLS-II hard X-ray FEL is starting at SLAC National Accelerator Laboratory. This facility will ultimately accelerate electrons to 8 GeV, with beams of 375 kW at 1 MHz. At such high-powers, errant beams will need to be detected very fast -200 μs- to limit exposure and to protect beam-line and safety components. Currently, LCLS-I uses ion chambers both as Point Beam Loss Monitors (PBLM) by collimators, dumps, septa, etc., and also as Long Beam Loss Monitors (LBML) that provide detection coverage in extended areas where the accelerator enclosure is not sufficiently thick to shield full beam losses. But due to the finite ion mobility and related screening effects, ion chambers are not fast enough, and their response would not be linear at high charge rates. LCLS-II will use synthetic mono-crystalline diamond chips as PBLMs, as those offer nanosecond time resolution due to the high mobility of holes generated in the valence band by charged particles. LBLMs will be 200 m-long optical fibers, with photomultipliers to detect Cerenkov photons produced by charged particles in the fibers. Use of these technologies requires tests and models to correlate their response to different beam losses. Response functions for these detectors have been developed for the FLUKA Monte Carlo code. After benchmarking the models, these have been applied to place PBLMs at locations where signal is relatively insensitive to beam-strike uncertainties and sufficiently above electronic noise, while keeping lifetime to radiation-damage long. Also, topologies where found were one PBLM can protect several components, resulting in cost reductions. As for LBLMs, the existing model helps scale signals for different beam loss configurations as a function of the fiber position.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB102  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB104 Improvements in Long-Term Orbit Stability at NSLS-II 4070
 
  • Y. Hidaka, A. Caracappa, Y. Hu, B. Podobedov, R.M. Smith, Y. Tian, G.M. Wang
    BNL, Upton, Long Island, New York, USA
 
  Funding: The study is supported by U.S. DOE under Contract No. DE-SC0012704.
We report our latest efforts to further improve long-term orbit stability at NSLS-II, on top of what is already provided by fast orbit feedback (FOFB) system. A DC local bump generation program, only utilizing RF beam position monitors (BPM) and compatible with FOFB, was first implemented and deployed in operation successfully, allowing on-demand fine adjustments of beamline source positions and angles. Then we introduced a simple feedback version that performs these bump corrections automatically as needed to maintain the sources within in 1 um/urad for select beamlines. In addition, an RF frequency feedback was also implemented to improve stability for 3-pole wigglers and bending magnet users. As a parallel effort, X-ray BPMs were included in a local feedback system to stabilize photon beam motion for several ID beamlines. However, this feedback scheme is not transparent to FOFB, and suspected to be the source of occasional saturation of fast corrector strength. As an alternative solution, the local bump program and its feedback version has been recently upgraded to include bumps with X-ray BPMs and in operation since April 2019.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB104  
About • paper received ※ 19 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB105 ESS Klystron Production Test Stand 4074
 
  • I. Roth, M.P.J. Gaudreau, M.K. Kempkespresenter, N. Silverman, R.E. Simpson
    Diversified Technologies, Inc., Bedford, Massachusetts, USA
 
  Diversified Technologies, Inc. (DTI) has delivered a new long-pulse modulator klystron test stand to Communication and Power Industries (CPI) in Palo Alto, CA for full power testing of production VKP-8292A klystrons for the European Spallation Source (ESS). This test stand was built using hardware and designs from an earlier SBIR effort for the US Department of Energy, with modifications to support ESS requirements and klystron testing operation. Earlier versions of this design are in use at IPN Orsay and CEA Saclay in France to test RF components for ESS. This new klystron test stand allows testing of klystrons at the full ESS specifications: 100 kV, 50 A, 3.5 ms pulse, 14 Hz,. This design is based on a (patent pending) non-dissipative regulator that compensates for the capacitor droop voltage (~20%) during the pulse. This allows a much smaller capacitor than would nominally be required for the long ESS pulse, eliminating the need for larger, more expensive capacitor bank. This test stand will speed delivery of ESS klystrons, and similar, long pulse, high power klystrons at CPI.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB105  
About • paper received ※ 19 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB107 A Novel Design of a Laser Phase Monitor for AWA RF Photocathode Electron Gun 4076
 
  • W. Liu, M.E. Condepresenter, D.S. Doran, G. Ha, J.G. Power, J.H. Shao, C. Whiteford, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
 
  It is critical to maintain a stable laser phase for RF photocathode electron gun to achieve high beam stability. In order to achieve a higher beam stability for AWA(Argonne Wakefield Accelerator) beamline, a novel laser phase monitor has been designed to allow us to monitor and feedback on. Both the design and its applications at AWA are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB107  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB108 LBNF Hadron Absorber: Updated Mechanical Design and Analysis for 2.4 MW Operation 4078
 
  • A. Deshpande, K. Anderson, K. E. Gollwitzer, B.D. Hartsell, J. Hylen, V.I. Sidorov, S. Tariq
    Fermilab, Batavia, Illinois, USA
 
  The Long-Baseline Neutrino Facility (LBNF) Hadron Absorber is located downstream of the decay pipe. It consists of actively cooled aluminum and steel blocks surrounded by steel and concrete shielding. Majority of the beam power is deposited in the absorber core which is water cooled. The surrounding steel and concrete shielding are air-cooled. The absorber provides radiation protection to personnel and keeps soil and ground activation levels to below allowable limits. It is designed for 2.4 MW beam operations. The total heat load deposited into the absorber is approximately 400 kW. The current design considers the longer 4-interaction length target of the optimized beam design. In addition, the ‘bafflette’ around the target reduces the energy deposited into the absorber. For this reason, the sculpting in the aluminum core blocks, which was in the previous design, was removed, making the design uniform and less complicated. In addition, the uniformity of the absorber makes it easier to understand the muon monitor data. Steady state thermal, structural, and Computational Fluid Dynamics (CFD) analysis of critical absorber aluminum and steel components during steady state operations is discussed herein. A similar analysis for a 120 GeV, 10 µs pulse, accident condition is also discussed. A preliminary design for the accident pulse prevention system that protects the absorber is also described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB108  
About • paper received ※ 30 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB112 Commission of the Transverse Bunch-by-Bunch Feedback at SPEAR3 4081
 
  • K. Tian, W.J. Corbett, X. Huang, N. Kurita, D.J. Martin, J.A. Safranek, J.J. Sebek
    SLAC, Menlo Park, California, USA
  • D. Teytelman
    Dimtel, San Jose, USA
 
  Funding: Work supported by US Department of Energy Contract DE-AC03-76SF00515.
Driven by the demand of suppressing transverse beam instabilities and developing novel short pulse operation modes in SPEAR3 storage ring, a wide-band transverse bunch-by-bunch feedback system has been recently commissioned for SPEAR3 storage ring. The system was demonstrated to be sufficient to suppress the transverse coupled bunch instabilities caused by trapped RF modes in one of the in vacuum insertion devices. A new function of beam instability interlock has been developed and is part of machine protection system for the in vacuum insertion device. In addition, the bunch-by-bunch feedback system serves as a indispensable diagnostic tool that enables us to measure machine parameters, beam impedance, and characteristics of the beam instability modes. In this paper, we describe the scheme and performance of the bunch-by-bunch feedback system at SPEAR3.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB112  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB113 Concept of Beam-Related Machine Protection for the Future Circular Collider 4085
 
  • Y.C. Nie, R. Schmidt, J.A. Uythoven, C. Wiesner, D. Wollmann, M. Zerlauth
    CERN, Meyrin, Switzerland
 
  In the Future Circular Collider (FCC) study, a proton-proton circular collider (FCC-hh) is considered with a stored beam energy 20 times higher than that of the LHC. Any uncontrolled release of such energy could potentially result in severe damage to the accelerator components. Machine protection of the FCC-hh is hence very important and challenging. With a machine-protection strategy similar to the LHC, FCC would require up to three turns to dump the beam synchronously after a failure detection. Due to several possible ultrafast failures, which could lead to significant beam losses in a few turns, it is important to further reduce the reaction time of the machine protection system (MPS) for the FCC. Reducing the detection time of a failure by using faster beam monitors, e.g. diamond detectors, can reduce the time between a beam loss and the beam dump request. Communication delay of the interlock system to the beam dumping system can be reduced by using a more direct signal path. More than one beam-free abort gap will shorten the time required for the synchronization between the abort gap and the extraction kicker. Different failure scenarios are classified according to the speed of the failure onset and the subsequent increase of induced beam losses. The critical failure modes, their potential mitigations and impacts on the design of the MPS are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB113  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB115 MicroTCA Based LLRF Control Systems for TARLA and NICA 4089
 
  • P. Nonn, Ç. Gümüş, C. K. Kampmeyer, H. Schlarb, Ch. Schmidt, T. Walter
    DESY, Hamburg, Germany
 
  The MicroTCA Technology Lab (A Helmholtz Innovation Lab) is preparing two turn-key Low Level RF control systems for facilities outside of DESY. The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is a 40 MeV electron accelerator with continuous wave (CW) RF operation. The MicroTCA based LLRF control system is responsible for two normal conducting and four superconducting cavities, controlling the RF as well as cavity tuning via motors and piezos. The Light Ion Linac (LILAC) is one of the injectors for the Nuclotron-based Ion Collider Facility (NICA) in Dubna, Russia. It will provide a 7 MeV/u pulsed, polarized proton or deuteron beam. The MicroTCA based LLRF control system will control five normal conducting cavities, consisting of one RFQ, one buncher, one debuncher and two IH-cavities. MicroTCA Technology Lab is cooperating with BEVATECH GmbH, Frankfurt, Germany, who designed the cavities. This paper gives a brief overview of the design of both LLRF systems as well as the status of their assembly.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB115  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB116 Effect of Ground Motion Introduced by HL-LHC CE Work on LHC Beam Operation 4092
 
  • M. Schaumann, D. Gamba, M. Guinchard, L. Scislo, J. Wenninger
    CERN, Geneva, Switzerland
 
  Funding: Research supported by the HL-LHC project
The official groundbreaking of the civil engineering (CE) work for the high luminosity upgrade of the LHC started on 15 June 2018 parallel to LHC beam operation. Compactor work and shaft excavation around the two low beta experiments, ATLAS and CMS, were expected to induce vibrations to the accelerator magnets and cause orbit disturbance, beam loss and potentially premature beam dumps. Ground motion sensors were installed on the surface and close to the triplets, where the CE works were expected to have the largest impact on the beams. This paper discusses the observations made on the LHC beams that could be correlated to CE work.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB116  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB117 Stability and Reliability Issues of PAL-XFEL Modulator 4096
 
  • S.H. Kim, H.-S. Kang, K.H. Kim, H.-S. Lee, C.-K. Min, S.S. Park, Y.J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  Funding: This work is supported by Ministry of Science, ICT(Information/Communication Technology) and Future Planning.
The Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL) employs 51 units of the pulse modulator in order to obtain the 10 GeV electron beam, which drive one X-band to linearize and 50 S-band klystrons. The PAL-XFEL requires very tight control of the klystron RF phase jitter 0.03-degree for S-band RF, 0.1-degree for X-band RF and the beam voltage stability of below 50 ppm. The RF phase jitter is directly related to the amplitude stability of modulator output pulses. There are several factors to satisfy the stability and reliability for the PAL-XFEL modulator. The largest sources of pulse-to-pulse instability are a current charging power supply (CCPS) for PFN charging, a thyratron switch, and a klystron focusing magnet power supply (MPS). In this paper, the operation and debugging results of those devices are described.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB117  
About • paper received ※ 16 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB118 Study on the Influence of the Range Shifter Material in a Scanning Nozzle for Proton Therapy Based on Monte Carlo Method 4100
 
  • Y.C. Yu, H.D. Guo, Y.Y. Hu, X.Y. Li, Y.J. Lin, P. Tan, X.D. Tupresenter, L.G. Zhang
    HUST, Wuhan, People’s Republic of China
 
  Range shifter plays a key role in decreasing the energy of the proton beam to realize shallow tumours treatment with the scanning nozzle in Huazhong University of Science and Technology Proton Therapy Facility (HUST-PTF). To control the transverse scattering and decrease the damage to healthy tissue caused by secondary particle, influence of the range shifter material was studied. In this paper, the Monte Carlo software Geant4 and FLUKA are applied to analyse the transport process of proton beam in the range shifters made of six different materials: PMMA, Lexan, Lucite, Polyethylene, Polystyrene, and Wax. The beam spot sizes at the iso-center with or without range shifter was calculated for the HUST-PTF scanning nozzle. The relationship between the thickness of the range shifters of the six materials and the proton energy was obtained. The secondary neutron yield at the end of the nozzle was also analysed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB118  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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