Keyword: resonance
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MOYPLM1 Challenges to Higher Beam Power in J-PARC: Achieved Performance and Future Prospects operation, extraction, experiment, proton 6

• S. Igarashi
KEK, Ibaraki, Japan

J-PARC is a world leading intensity frontier accelerator facility, consisting of a 400-MeV H linac, a 3-GeV Rapid Cycling Synchrotron (RCS) and a 30-GeV slow cycling Main Ring synchrotron (MR). The RCS delivered a 500 kW beam (4.2·1013 particles per pulse (ppp)) to the Material and Life science experimental Facility (MLF) in April of 2018, The design power of 1 MW will be delivered in the next few years. Construction of a second target station (2TS) of the MLF with beam power upgraded to 1.5 MW is now under discussion. The MR delivers proton beam to a long-baseline neutrino oscillation experiment, T2K, by fast extraction (FX) and to the hadron experimental facility by slow extraction (SX). For the FX, the maximum beam power is 475 kW and 2.5·1014 ppp, the world highest ppp in synchrotrons, and for the SX 51 kW and 5.5·1013 ppp with an extremely high extraction efficiency of 99.5 %. To achieve 1.3 MW beam power for the neutrino experiment, upgrades to allow operation with a higher repetition rate are planned. The talk will review recent progress of J-PARC facility by highlighting technical challenges toward higher beam power together with future prospects.
Slides MOYPLM1 [9.193 MB]
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOYPLM1
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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MOPGW087 GALACTIC and GALACLIC: Two Vlasov Solvers for the Transverse and Longitudinal Planes impedance, synchrotron, simulation, coupling 312

• E. Métral
CERN, Geneva, Switzerland

GALACTIC and GALACLIC, two Vlasov solvers for the study, in the transverse and longitudinal plane respectively, of single-bunch coherent oscillation modes, were recently developed starting from the Vlasov equation and using a decomposition on the low-intensity eigenvectors, as proposed by Laclare and Garnier. The first Vlasov solver was used for instance to shed light on the destabilising effect of resistive transverse dampers and the second helped understanding the details of the mode-coupling behind some longitudinal microwave instabilities. Both theories are reviewed in detail, highlighting in particular the similarities and peculiarities of the two approaches.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW087
About • paper received ※ 23 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPGW099 Vlasov-Fokker-Planck Simulations of Passive Higher-Harmonic Cavity Effects in ALS-U cavity, simulation, impedance, synchrotron 357

• G. Bassi
BNL, Upton, Long Island, New York, USA

Funding: Work supported by DOE under contract DE-SC0012704
We discuss numerical simulations of the Vlasov-Fokker-Planck equation to model passive higher-harmonic cavity (HHC) effects with parameters of the Advanced Light Source Upgrade (ALS-U. The numerical results, obtained with the SPACE code, are compared with a modal analysis of the coupled-bunch instability theory.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW099
About • paper received ※ 18 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019
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MOPGW105 Preliminary Lattice Studies for the Single-Invariant Optics Experiment at the University of Maryland lattice, experiment, octupole, optics 367

• L. Dovlatyan, T.M. Antonsen, B.L. Beaudoin, I. Haber, D.B. Matthew
UMD, College Park, Maryland, USA
• K.J. Ruisard
ORNL, Oak Ridge, Tennessee, USA

Funding: This work is supported through DOE-HEP Award DESC0010301 and NSF Award PHY1414681.
A novel approach to transverse resonance suppression in next generation high-intensity accelerators is the use of nonlinear optical elements to induce large tune spreads which result in reduced responses to resonance driving perturbations*. In order to test this theory, we have built and characterized an octupole channel insert for use in the University of Maryland Electron Ring (UMER). This paper presents experimental lattice studies using a low space-charge intensity beam at an energy of 10keV with a beam current of ~150uA, tune depression < 0.005, and unnormalized RMS emittance of 4.3 mm-mr. We apply beam based measurement techniques in order to evaluate the quality of our single-invariant lattice and better understand the nonlinearities created by the octupole channel.
* V. Danilov and S. Nagaitsev, Nonlinear accelerator lattices with one and two analytic invariants, PRSTAB, 13, 084002, 2010.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW105
About • paper received ※ 11 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPGW107 Study of Integrable and Quasi-Integrable Sextupole Lattice sextupole, focusing, lattice, optics 371

• L. Gupta, Y.K. Kim
University of Chicago, Chicago, Illinois, USA
• S. Baturin
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
• S. Nagaitsev
Fermilab, Batavia, Illinois, USA

Funding: Funded through Center for Bright Beams, NSF award PHY-1549132
In order to maximize beam lifetime in circular particle accelerators, the nonlinear beam optics are optimized to maximize the dynamic aperture of the beam. The dynamic aperture (DA), which is a 6-D phase space volume of stable trajectories, depends on the strength of the nonlinearities in the machine, and is calculated via particle tracking. Current DA optimization processes include multi-objective genetic algorithm optimizers, and relies on minimizing the magnitudes of resonance driving terms (RDT), which are calculated from the nonlinear contribution to the one-turn-map. The process of searching through the parameter space for an ideal combination that maximizes DA is computationally strenuous. By setting up the sextupole channel such that it is resembles a symplectic integrator of a smooth Hamiltonian, with only a few sextupoles we are able to closely reproduce phase space trajectories of a smooth Hamiltonian up to the hyperbolic point. No chaos and resonances are observed if phase advance per one sextupole magnet in the channel does not exceed ~0.12x2 pi. Therefore, an important property of the suggested approach is the intrinsic elimination of the resonances, and minimization of corresponding RDTs.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW107
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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MOPGW125 Lossless Crossing of 1/2 Resonance Stopband by Synchrotron Oscillations experiment, lattice, betatron, storage-ring 410

• G.M. Wang, Y. Li, J. Rose, T.V. Shaftan, V.V. Smaluk
BNL, Upton, Long Island, New York, USA

Funding: DOE under contract No.DE-AC02- 98CH10886
Modern high performance circular accelerators require sophisticated corrections of nonlinear lattices. The beam betatron tune footprint may cross many resonances, reducing dynamic aperture and causing particle loss. However, if particles cross a resonance reasonably fast, the beam deterioration may be minimized. In this paper, we present the experiments with the beam passing through a half-integer resonance stopband via chromatic tune modulation by exciting synchrotron oscillations. This is the first time that beam dynamics have been kept under precise control while the beam crosses a half-integer resonance. Our results convincingly demonstrate that particles can cross the half-integer resonance without being lost if the passage is reasonably fast and the resonance stopband is sufficiently narrow.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW125
About • paper received ※ 13 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPMP012 Concepts of Longitudinally Polarized Electron and Positron Colliding Beams in the Circular Electron Positron Collider polarization, positron, electron, wiggler 445

• Z. Duan, J. Gao, X.P. Li, D. Wang, Y. Wang, W.H. Xia, Q.J. Xu, C.H. Yu, Y. Zhang
IHEP, Beijing, People’s Republic of China

Funding: Work supported by National Key Research and Development Program of China (No.2018YFA0404300).
This paper reports some preliminary study into the imple- mentation of longitudinally polarized e+/e colliding beams in the Circular Electron Positron Collider, at a center of mass energy of 91 GeV as a Z factory and energies beyond.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP012
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPMP052 Numerical Simulations of the DC Wire Prototypes in LHC for Enhancing the HL-LHC Performances experiment, simulation, luminosity, optics 566

• A. Poyet
Université Grenoble Alpes, Grenoble, France
• S.D. Fartoukh, N. Karastathis, Y. Papaphilippou, K. Skoufaris, G. Sterbini
CERN, Geneva, Switzerland

For the last 15 years, the compensation of the Beam-Beam Long-Range (BBLR) interaction in colliders using DC wires has been studied. In 2015, in the frame of the HL-LHC project, it has been shown that a compensation of all the Resonance Driving Terms (RDTs) generated by the BBLR interaction is possible using wires with constraints on their transverse and longitudinal positions. In 2017, an experimental campaign has been launched in the present LHC, with wires installed in sub-optimal positions due to integration constraints. The aim of this paper is therefore to apply the formalism developped for HL-LHC to the LHC case and to compare the experimental results to the numerical tracking studies of the compensation using wires.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP052
About • paper received ※ 06 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPRB021 Remodeling of 150 MeV FFAG Main Ring at KURNS to Pion Production Ring FFAG, proton, target, focusing 616

• K. Suga, Y. Fuwa, Y. Ishi, Y. Kuriyama, Y. Mori, H. Okita, T. Uesugi
Kyoto University, Research Reactor Institute, Osaka, Japan

A possibility of remodeling main ring of 150 MeV FFAG accelerator at Kyoto University, Institute for Integrated Radiation and Nuclear Science (KURNS) to Pion Production Ring (PPR) for muon transmutation study has been discussed. Design was made on the assumption that 400 MeV proton beams circulate and hit a target in the ring to generate pions. Optimizations of lattice parameters and 3D magnet modeling are reported.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB021
About • paper received ※ 30 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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MOPRB041 Spin Resonance Strength in the Transparent Spin Mode of the NICA Collider polarization, solenoid, proton, collider 656

MIPT, Dolgoprudniy, Moscow Region, Russia
• A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia
• A.D. Kovalenko
JINR, Dubna, Moscow Region, Russia

To implement the polarization program at the NICA complex (Dubna, Russia) the novel mode of ion polarization control - the transparent spin mode - is planned to use. To set up the transparent spin mode in the NICA collider two solenoidal snakes will be placed in straights of the Multi Purpose Detector (MPD) and the Spin Physics Detector (SPD). The beam polarization at SPD will be controlled by means of ‘‘weak’’ solenoids. The main characteristic of the transparent spin mode is the spin resonance strength, which consists of two parts: a coherent part arising due to additional transverse and longitudinal fields on the beam trajectory deviating from the design orbit and an incoherent part associated with the particles’ betatron and synchrotron oscillations (beam emittances). The resonance strength allows one to formulate requirements on the magnitudes of the control solenoids’ fields. The theoretical analysis, calculation and spin tracking simulation of the spin resonance strength in the whole momentum range of the NICA collider are presented.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB041
About • paper received ※ 01 May 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019
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MOPRB062 nuSTORM Decay Ring lattice, quadrupole, closed-orbit, emittance 716

• J.-B. Lagrange
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
• R.B. Appleby, S.C. Tygier
UMAN, Manchester, United Kingdom
• J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
• J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

Precise neutrino cross section measurements and search for sterile neutrinos can be done with neutrino beams produced from muons decaying in a storage ring due to its precisely known flavour content and spectrum. In the proposed nuSTORM facility pions would be directly injected into a racetrack storage ring, where circulating muon beam would be captured. The storage ring has three options: a FODO solution with large aperture quadrupoles, a racetrack FFA (Fixed Field Alternating gradient) using the recent developments in FFAs and a hybrid solution of the two previous options. Machine parameters, linear optics design and beam dynamics of the hybrid solution are discussed in this paper.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB062
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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MOPRB082 Scaling Properties of the Synchro-Beta Resonance in Crab Crossing Scheme of Future Electron Ion Collider luminosity, electron, simulation, cavity 766

• Y. Hao, Y. Luo, V. Ptitsyn
BNL, Upton, Long Island, New York, USA
• J. Qiang
LBNL, Berkeley, California, USA

The synchro - beta resonance due to the beam-beam interaction was predicted by the strong-strong simulation in the future electron-ion collider designs. In this paper, we study the scaling properties of the degradation rate of this unwanted resonance. These studies motivated the possible countermeasures of the luminosity degradation associated with the resonance.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB082
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPTS022 Current Status of the MYRRHA Cavities cavity, status, operation, vacuum 892

• K. Kümpel, D. Bade, M. Busch, D. Koser, S. Lamprecht, N.F. Petry, H. Podlech, S. Zimmermann
IAP, Frankfurt am Main, Germany

The MYRRHA (Multi-purpose hYbrid Research Reac-tor for High-tech Applications) Project is a planned ac-celerator driven system (ADS) for the transmutation of long-living radioactive waste. In order test the reliability of the planned 17 MeV injector, a shortened injector with 5.9 MeV consisting of the ion source, a 4-Rod RFQ, 2 Quarter Wave Rebunchers (QWRs) and a total of 7 normal conducting CH structures is currently being installed in Louvein-la-Neuve (LLN, Belgium). Before the cavities can be tested with beam, they are subjected to so-called low power tests several times during the individual con-struction stages in order to be able to correct any devia-tions. This paper describes the status of the two Quarter Wave Rebunchers, which are currently in the process of copper plating and final acceptance, as well as the first two CH structures, the first of which is already being conditioned while CH 2 is still in preparation.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS022
About • paper received ※ 10 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPTS037 Comparison Between Measurement and Simulation of a Full Scale Prototype for the Proton Injector at FAIR cavity, simulation, proton, linac 940

• A. Seibel, C.M. Kleffner, K. Knie, M. Vossberg
• U. Ratzinger
IAP, Frankfurt am Main, Germany

A dedicated 68 MeV, 70 mA proton injector is required for the research program at FAIR (Facility for Antiproton and Ion Research). This 325 MHz linear injector contains a RFQ and six CH structures. The CH (Crossbar H-mode) structures are working in the H210 mode. The main acceleration of this room temperature linac will be provided by the CH structures. For the second acceleration from 11.5 MeV to 24.2 MeV a full scale prototype has been built. This structure consists of two individual CH resonators and a coupling cell. Inside the structure there are 17 tuners, they have an impact on the electric field and the frequency. For operation a flat field is required, therefore this tuners must be correctly positioned. Some series of low level tuning and frequency measurements were done to determine the size of the tuners. Low level measurements and simulations will be compared and presented.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS037
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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MOPTS038 BEAM DYNAMICS OF HIGH CHROMATICITY LATTICE FOR IRANIAN LIGHT SOURCE FACILITY (ILSF) STORAGE RING storage-ring, lattice, dynamic-aperture, optics 943

• F. Foroughi, S.M. Jazayeri
IUST, Narmac, Tehran, Iran
• E. Ahmadi, S. Dastan, J. Rahighi
ILSF, Tehran, Iran

One of the limiting factors of electron beam lifetime in low emittance storage rings is Head-Tail (HT) insta-bility. Low emittance storage rings typically have a large negative natural chromaticity due to the strong quadru-poles. Above transition large negative natural chroma-ticity leads to large Head-Tail instability which limit the beam lifetime. Since the threshold current of HT insta-bility is directly related to linear chromaticity, increasing the linear chromaticity to slightly positive value is a solution to prevent HT instability. In this paper we in-creased the chromaticity of Iranian Light Source Facility (ILSF) to (+4, +4) and we will investigate the beam dy-namics of ILSF 3GeV storage ring in high chromaticity. For reaching this aim we have used two families of sex-tupoles for chromaticity correction and then optimized them to maximize the dynamic aperture and Touschek lifetime. The beam dynamics of high chromaticity lattice is presented in this paper.
Foroughi.farangis@gmail.com

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS038
About • paper received ※ 29 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPTS077 RCCS Operation and Characteristics in Resonance Frequency Control Mode at KOMAC controls, DTL, operation, radio-frequency 1025

• K.H. Kim, H.S. Jeong, H.S. Kim, S.G. Kim, H.-J. Kwon, Y.G. Song
Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea

Funding: This work has been supported through KOMAC (Korea Multi-purpose Accelerator Complex) operation fund of KAERI by MSIT (Ministry of Science and ICT)
A 100-MeV proton accelerator is under operation at Korea Multi-purpose Accelerator Complex (KOMAC). The resonance control cooling system (RCCS) has supplied the cooling water to drift tube linac (DTL). The DTL need to keep the resonant frequency of 350MHz during the operation. RCCS has a critical role in sustaining the acceptable resonant frequency error in DTL by adopting the resonance frequency control mode. Details on the RCCS operation in resonance frequency control mode will be given in this study.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS077
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPTS079 Design of 1.5 GeV Compact Storage Ring for the EUV and Soft X-rays storage-ring, quadrupole, synchrotron, focusing 1028

• J.Y. Lee, I.G. Jeong
Korea Atomic Energy Research Institute (KAERI), Daejeon, Republic of Korea
• P. Buaphad, Y.J. Joo, H.R. Lee
University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
• P. Buaphad, Y.J. Joo, Y. Kim, H.R. Lee, S. Lee
KAERI, Jeongeup-si, Republic of Korea

Recently, there has been discussions about the need for the next-generation synchrotron light source facility in Korea. The facility in consideration is composed of a super-conducting linear accelerator for the injector, a storage ring for the EUV and soft X-rays, and a main storage ring for hard X-rays. In this study, design concepts of the soft X-ray storage ring is presented. To effectively utilize the small space allocated for the soft X-ray storage ring, a compact storage ring is taken into account. The compact storage ring is a synchrotron accelerator of which diameter is shorter than the length of injector beamline. In this paper, we report design concepts and optimization of the compact storage ring for the EUV and soft X-ray users. The lattice of the storage ring is modelled by utilizing ELEGANT simulation code to optimize beam parameters and performance of the ring.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS079
About • paper received ※ 24 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019
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MOPTS080 Status and Installation Plan of RISP RFQ at Project Site rfq, site, cavity, experiment 1031

• B.-S. Park, I.S. Hong
IBS, Daejeon, Republic of Korea

Funding: Supported by the Rare Isotope Science Project of Institute for Basic Science funded by the Ministry of Science, ICT (MSIP) and the National Research Foundation (NRF) of Korea (2013M7A1A1075764).
The Rare Isotope Science Project (RISP) at Institute for Basic Science (IBS) has been developed a Radio Frequency Quadrupole(RFQ), which was fabricated and commissioned at the off-site test facility. An O+7 beam was accelerated from 10keV/u to 516keV/u as a preliminary beam test. For CW and high power operation, RF conditioning test was also conducted. The RISP RFQ is 5 meters long, 1 meter in diameter and weighs about 16 tons. It was disassembled and transported to the project site, Sin-dong, for installation as the injector system. The installation commenced in April 2019 and the commissioning of the injector system is expected to begin in early 2020. In this paper, the installation status and plans were summarized.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS080
About • paper received ※ 15 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019
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MOPTS086 Identification and Compensation of Betatronic Resonances in the Proton Synchrotron Booster at 160 Mev space-charge, injection, proton, emittance 1054

• A. Santamaría García, S.C.P. Albright, F. Antoniou, F. Asvesta, H. Bartosik, G.P. Di Giovanni, B. Mikulec
CERN, Geneva, Switzerland
• F. Asvesta
NTUA, Athens, Greece
• H. Rafique
University of Manchester, Manchester, United Kingdom

The Proton Synchrotron Booster (PSB) is the first circular accelerator in the injector chain to the Large Hadron Collider (LHC) and accelerates protons from 50 MeV to 1.4 GeV. The PSB will need to deliver two times the current brightness after the LHC Injectors Upgrade (LIU) in order to meet the High Luminosity LHC (HL-LHC) beam requirements. At the current injection energy a large incoherent space charge tune spread limits the brightness of the beams, which is one of the main motivations to increase the injection energy to 160 MeV with the injection provided by Linac4, a new H linear accelerator. The higher injection energy will allow doubling the beam intensity while maintaining a space charge tune spread similar to current values. The degradation of the beam brightness due to the tune spread can be minimized with a proper choice of working point and an efficient compensation of resonances. In this paper, we present the measurement of the betatronic resonances in the four rings of the PSB at 160 MeV before the Long Shutdown 2, as well as the results of a proposed compensation scheme.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS086
About • paper received ※ 13 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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TUPMP011 Storageless Resonant Converter for Accelerator Magnets operation, controls, simulation, storage-ring 1248

• M. Cautero, T. N. Gucin
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Elettra Sincrotrone Trieste, a specialized research centre generating high quality synchrotron radiation, has been in operation since 1993 and was revised in 2009. Recently, Elettra has been funded for a complete renewal of the storage ring. For the new machine, it is planned to employ state of the art converters, mostly of which will be designed in-house. For this purpose, it has been decided to evaluate the performance of a storage-less resonant converter, pro-posed by Dr. Slobodan Ćuk, which is a step down DC/DC converter consisting of four switches, one resonant capac-itor and two resonant inductors. For this purpose, the voltage conversion ratio of the converter has been de-rived. The topology was confirmed with simulation and a PCB layout has been designed, which is still to be tested.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP011
About • paper received ※ 08 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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TUPGW012 Sensitivity Studies of the PETRA IV Lattice alignment, emittance, simulation, site 1408

• I.V. Agapov
DESY, Hamburg, Germany

As the machine with the smallest emittance among the planned fourth-generation hard x-ray synchrotron light sources, PETRA IV will have very demanding requirements on magnet alignment and stability. Several developments to address mechanical and beam-based stabilization have been started in connection to that. Here we summarize the alignment and field error tollerances resulting from startup and commissioning simulations of the main ring. Novel high level control tools will be required to assure smooth operation of the machine; progress in their development and beam test results at PETRA III will be reported.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW012
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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TUPGW013 Tune and Chromaticity Optimization at Bessy II for the Transverse Resonant Island Bucket Optics optics, simulation, photon, emittance 1411

• F. Armborst, P. Goslawski, A. Jankowiak
HZB, Berlin, Germany

Funding: Federal Ministry of Education and Research
Transverse Resonant Island Buckets (TRIBs *) correspond to a second stable orbit, longitudinally winding around the core orbit in the transverse x-x-phasespace. The exploitation possibilities for stable TRIBs are under investigation at the third generation light source BESSY II in Berlin. The applicability for bunch separation is a main subject of these studies. Stable operation of TRIBs optics with a single or few bunches on the second orbit and a multibunch train on the main orbit has been shown **. Photons emitted on the second orbit are well separated from those of the main orbit at all beamlines. This provides the possibility of bunch separation by beamline adjustment for the timing community without significant impact on the average brightness for other users. Simulations based on linear optics from closed orbits (LOCO) and on nonlinear optics derived from the measured chromaticity and tune shift with action (TSWA) predict this separation well. Friendly user experiments in 2018 confirmed these results. The scheduled upgrade BESSY VSR *** features simultaneously stored long and short bunches. Then TRIBs optics would in principle enable the separation of the different bunches at every beamline offering unique possibilities to our users. Simulations and measurements aiming to investigate further possible optimization of the TRIBs optics are presented.
* F. Armborst, P. Goslawski et al, DOI: 10.18429/JACoW-IPAC2018-TUPML052
** P. Goslawski, F. Armborst et al. DOI: 10.18429/JACoW-IPAC2017-WEPIK057
*** A. Jankowiak et al., DOI: 10.5442/R0001

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW013
About • paper received ※ 14 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019
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TUPGW032 Mode-Locked Pulse Oscillation of a Self-Resonating Enhancement Optical Cavity cavity, laser, controls, feedback 1471

• Y. Hosaka
QST/Takasaki, Takasaki, Japan
• Y. Honda, T. Omori, J. Urakawa
KEK, Ibaraki, Japan
• A. Kosuge
ISSP, Kashiwa-shi, Japan
• K. Sakaue
The University of Tokyo, The School of Engineering, Tokyo, Japan
• T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
• Y. Uesugi
Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, Sendai, Japan
• M. Washio
Waseda University, Tokyo, Japan

A power enhancement optical cavity is a compelling means of realizing a pulsed laser with a high peak power and high repetition frequency, which is not feasible using a simple amplifier scheme. However, a precise feedback system is necessary for maintaining the narrow resonance condition of the optical cavity; this has become a major technical issue in developing such cavities. We have developed a new approach that does not require any active feedback system, by placing the cavity in the outer loop of a laser amplifier. We report on the first demonstra-tion of a mode-locked pulse oscillation using the new system.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW032
About • paper received ※ 15 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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TUPGW108 Characterization of NEG Coatings for SLS 2.0 GUI, impedance, coupling, vacuum 1662

• M.M. Dehler, A. Citterio
PSI, Villigen PSI, Switzerland
• S. Alberti, J.P. Hogge
SPC-EPFL, Lausanne, Switzerland
• M. Hahn, H.P. Marques
ESRF, Grenoble, France
• X.Y. Liu
USTC/NSRL, Hefei, Anhui, People’s Republic of China

To limit desorption and ameliorate pumping of the narrow 20 mm aperture vacuum chamber of SLS2.0, it is planned to fully coat it with nonevaporable getter (NEG) material. NEG coating can be produced with different structural characteristics, from dense films to columnar growth, with corresponding distinct electrical properties affecting the machine impedance and the instability threshold of the accelerator. In order to evaluate and characterize the coating process for geometries similar to the SLS chamber, we measured the resonance properties of coated and uncoated shorted waveguide pieces. First tests were done with standard X band waveguides at 12 and 7 GHz. Test setups using elliptical cross sections are in preparation, also for higher frequencies allowing the characterization of thin NEG layers. The final goal is to have a standardized process to test of samples coated by external producers. We describe the setups and first results.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW108
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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TUPRB035 Stimulated Emission of THz Coherent Diffraction Radiation in an Optical Cavity by a Multibunch Electron Beam cavity, experiment, radiation, electron 1763

• Y. Honda, A. Aryshev, R. Kato, T. Miyajima, T. Obina, M. Shimada, R. Takai, T. Uchiyama, N. Yamamoto
KEK, Ibaraki, Japan

Funding: JSPS KAKENHI
Accelerator-based terahertz (THz) radiation has been expected to realize a high-power broad-band source. Employing a low-emittance and short-bunch electron beam at a high repetition rate, a scheme to resonantly excite optical cavity modes of THz spectrum range via coherent diffraction radiation has been proposed. The confocal cavity design is the special case that resonance conditions of all the eigen modes coincide, resulting in realizing broad-band excitation. But in general cases of non-confocal cavities, the resonance condition depends on the mode, and the resonance peak becomes wide and weak. We performed an experiment with a non-confocal cavity as a follow-up experiment of that we have done with a confocal cavity. The result confirmed that the confocal design is the key for a broad-band source.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB035
About • paper received ※ 26 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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TUPTS033 J-PARC RCS: High-Order Field Components Inherent in the Injection Bump Magnets and Their Effects on the Circulating Beam During Multi-Turn Injection injection, simulation, sextupole, operation 2009

• H. Hotchi, H. Harada, T. Takayanagi
JAEA/J-PARC, Tokai-mura, Japan

The J-PARC RCS utilizes four sets of pulsed dipole magnets for the formation of injection orbit bump. The injection bump magnets have a large aspect ratio (gap length/core length), so there are other high-order field components inherent in their magnetic fields in addition to the main dipole component. The high-order field components, which locally exist in the injection section not following the lattice super-periodicity, have a significant influence on the circulating beam during multi-turn injection via the excitation of high-order random betatron resonances. This paper discusses the detailed mechanism of emittance growth and beam loss caused by the high-order field components of the injection bump magnets including its correction scenario on the basis of numerical simulation and experimental results.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS033
About • paper received ※ 18 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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TUPTS108 Numerical Simulations of RHIC FY17 Spin Flipper Experiments simulation, experiment, dipole, polarization 2174

• P. Adams, H. Huang, J. Kewisch, C. Liu, F. Méot, P. Oddo, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, T. Roser
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Spin flipper experiments during RHIC Run 17 have demonstrated the 97% effectiveness of polarization sign reversal during stores. Zgoubi numerical simulations were setup to reproduce the experimental conditions. A very good agreement between the experimental measurements and simulation results was achieved at 23.8GeV, thus the simulations are being used to help optimize the various Spin Flipper parameters. The ultimate goal for these simulations is to serve as guidance towards a perfect flip at high energies to allow a routine Spin Flipper use during physics runs.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS108
About • paper received ※ 13 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019
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TUPTS109 Status of AC Dipole Project at Rhic Injectors for Polarized 3He, Update dipole, booster, vacuum, proton 2177

• K. Hock, C.W. Dawson, H. Huang, J.P. Jamilkowski, F. Méot, P. Oddo, M.C. Paniccia, Y. Tan, N. Tsoupas, J.E. Tuozzolo, K. Zeno
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
An ac dipole will be used for the efficient transport of polarized 3He in the AGS Booster as it is accelerated to |Gγ|=10.5. The ac dipole introduces a coherent vertical beam oscillation which allows preservation of polarization through the two intrinsic resonances Gγ=12-νy and Gγ=6+νy resonances, by full spin flipping. The AGS Booster ac dipole will be tested with protons crossing the Gγ=0+νy intrinsic resonance, which has ac dipole requirements similar to polarized 3He crossing the Gγ=12-νy resonance, providing a convenient proof of principle. This paper gives a status of the project.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS109
About • paper received ※ 13 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019
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TUPTS110 Scanning the AC Dipole Resonance Proximity Parameter in the AGS Booster dipole, booster, betatron, simulation 2179

• K. Hock, H. Huang, F. Méot, P. Oddo, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
An ac dipole system is installed in the AGS Booster in view of acceleration of polarized helion for RHIC and the eRHIC EIC. The amplitude of the vertical coherent oscillations induced by the ac dipole depends greatly on the resonance proximity parameter, δm, which is the distance between resonance tune and driving tune. Due to the non-zero momentum spread, particles with different momenta will have different value of δm. The rapid acceleration rate of the booster would cause δm to sweep, the amount of which would depend on the energy and the duration of the ac dipole cycle. These effects are simulated using zgoubi, which set a range of δm values suitable for both high spin flip efficiency and minimizing emittance growth, and the results of the simulations are discussed.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS110
About • paper received ※ 12 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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WEPMP014 Slow Extraction Study by Using Sextupole extraction, sextupole, synchrotron, proton 2332

• L. Huang, S. Wang
IHEP, Beijing, People’s Republic of China

The spill continuously extracted from synchrotron by using resonance sextupoles plays a key role in multidisciplinary application. The intensity of virtual sextupole and the spiral step for the typical synchrotron are obtained theoretically. A customized synchrotron of extraction components placed in dispersion section is designed and the tracking code of slow extraction is developed, thus the theoretical spiral step is comparative studied. To study the beam loss, three layouts of extraction are also designed based on the synchrotron. The result shows that the beam losses at extraction point are different for three cases and it is advantage to beam loss for extraction components placed in dispersion-free straight section.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP014
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019
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WEPGW075 Coupling Impedance Studies of the Current Transformers at ALBA impedance, cavity, simulation, factory 2647

• T.F.G. Günzel, U. Iriso, A.A. Nosych
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

ALBA is equipped with two different current transformers (FCT and DCCT), and a third one (ICT) is now in design stage to be installed in 2019. A comparative study of the different currents transformers was carried out in order to characterize their contribution to longitudinal and transverse impedance. The gap in the vacuum chamber of the current transformers was varied in order to study its effect on the heat deposited by the beam in the corresponding device and on the resonance in the longitudinal impedance spectrum. The simulation results are compared to the experience with the existing current transformers in operation.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW075
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019
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WEPGW122 EXPERIMENTAL VERIFICATION OF TRANSPARENT SPIN MODE IN RHIC polarization, collider, controls, experiment 2783

• V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang
JLab, Newport News, Virginia, USA
• P. Adams, H. Huang, F. Méot, V. Ptitsyn, W.B. Schmidke
BNL, Upton, Long Island, New York, USA
• Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, Russia
• H. Huang
ODU, Norfolk, Virginia, USA
• A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia

Funding: Supported in part by the U.S. DoE under Contract No. DE-AC05-06OR23177 and by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DoE.
High electron and ion polarizations are some of the key design requirements of a future Electron Ion Collider (EIC). The transparent spin mode, a concept inspired by the figure 8 ring design of JLEIC, is a novel technique for preservation and control of electron and ion spin polarizations in a collider or storage ring. It makes the ring lattice "invisible" to the spin and allows for polarization control by small quasi-static magnetic fields with practically no effect on the beam’s orbital characteristics. It offers unique opportunities for polarization maintenance and control in Jefferson Lab’s JLEIC and in BNL’s eRHIC. The transparent spin mode has been demonstrated in simulations and we now plan to test it experimentally. We present a design of an experiment using a polarized proton beam stored in one of the RHIC rings. In the experiment, one of the RHIC rings is configured in the transparent spin mode by aligning the axes of its two Siberian snakes. The experiment goals, procedures, hardware requirements and expected results are presented.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW122
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019
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WEPGW124 Spin Response Function for Spin Transparency Mode of RHIC collider, polarization, controls, lattice 2791

• V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang
JLab, Newport News, Virginia, USA
• P. Adams, H. Huang, F. Méot, V. Ptitsyn, W.B. Schmidke
BNL, Upton, Long Island, New York, USA
• Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, Russia
• H. Huang
ODU, Norfolk, Virginia, USA
• A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia

Funding: Supported by the U.S. DoE under Contracts No. DE-AC05-06OR23177 and DE-AC02-98CH10886.
In the Spin Transparency (ST) mode of RHIC, the axes of its Siberian snakes are parallel. The spin tune in the ST mode is zero and the spin motion becomes degenerate: any spin direction repeats every particle turn. In contrast, the lattice of a conventional collider determines a unique stable periodic spin direction, so that the collider operates in the Preferred Spin (PS) mode. Contributions of perturbing magnetic fields to the spin resonance strengths in the PS mode are usually calculated using the spin response function. However, in that form, it is not applicable in the ST mode. This paper presents a response function formalism expanded for the ST mode of operation of conventional colliders with two identical Siberian snakes in the highly-relativistic limit. We present calculations of the spin response function for RHIC in the ST mode.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW124
About • paper received ※ 01 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019
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WEPRB056 Design Study of 325MHz RF Power Coupler for Superconducting Cavity cavity, impedance, superconducting-cavity, simulation 2937

• J.Y. Yoon, H.J. Cha, S.W. Jang, E.-S. Kim, K.R. Kim, C.S. Park, S. H. Park
KUS, Sejong, Republic of Korea
• J. Bahng
Korea University Sejong Campus, Sejong, Republic of Korea
• K.R. Kim
PAL, Pohang, Kyungbuk, Republic of Korea

We present the design study of the RF input power coupler for 325 MHz superconducting cavities. The power coupler, based on a conventional coaxial transmission line, provides RF powers to the cavity up to 12kW in CW mode. The thermal interceptors are considered as 4.5 K and 40 K or 4.5 K and 77 K corresponding to the usage of liquid Helium only or both liquid Helium and Nitrogen for cryogenic temperature to reduce the thermal load. The transition box (T-box), which is assembled with power coupler, is designed and applied for impedance matching and inner conductor cooling.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB056
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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WEPRB065 Multi-physics Computation and Deformation Testing of a Shell-type 1.5-GHz Cavity cavity, SRF, experiment, synchrotron 2968

• M.-C. Lin, C.H. Lo
NSRRC, Hsinchu, Taiwan
• M. -R. Lu, M.-K. Yeh
NTHU, Hsinchu, Taiwan

Funding: Work supported by the Ministry of Science and Technology, R. O. C. (Taiwan) under grant NSC-100-2628-E-213-001-MY3.
A copper prototype of a 1.5-GHz cavity was manufac-tured to simulate a superconducting radio-frequency cavity for technique development. Frequency tuning with longitudinal compression of this prototype and cryogenic cooling with liquid nitrogen were performed to examine the numerical results from finite-element models, mainly the corresponding shifts of the fundamental resonant frequency. An appropriate element option improved the accuracy of the resonant frequency and the distribution of the magnetic field. Effects of geometry distortion of an uneven length on the frequency shift of this shell-type cavity as loaded on longitudinal compression are also examined and discussed.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB065
About • paper received ※ 25 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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WEPRB102 Correction of Crosstalk Effect in the LEReC Booster Cavity cavity, electron, booster, HOM 3051

• B. P. Xiao, K. Mernick, F. Severino, K.S. Smith, T. Xin, W. Xu
BNL, Upton, Long Island, New York, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
The Linac of Low Energy RHIC electron Cooler (LEReC) is designed to deliver a 1.6 MeV to 2.6 MeV electron beam, with peak-to-peak dp/p less than 7·10-4. The booster cavity is the major accelerating component in LEReC, which is a 0.4 cell cavity operating at 2 K, with a maximum energy gain of 2.2 MeV. It is modified from the Energy Recovery Linac (ERL) photocathode gun, with fundamental power coupler (FPC), pickup coupler (PU) and higher order mode (HOM) coupler close to each other. The direct coupling between FPC and PU induced crosstalk effect in this cavity. This effect is simulated and measured, and is further corrected using low level RF (LLRF) to meet the energy spread requirement.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB102
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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WEPTS018 Experimental Observation of Low-Order Collective Oscillation Modes in a Strong-Focusing Lattice quadrupole, plasma, dipole, experiment 3130

• K. Ito, H. Higaki, H. Okamoto
• T. Kurauchi
Hiroshima University, Faculty of Science, Higashi-Hirosima, Japan

In a conventional linear Paul trap (LPT), four electrode rods are placed symmetrically around the trap axis to generate a radio-frequency quadrupole field for transverse ion confinement. The periodic nature of the external focusing potential can give rise to serious ion losses under a specific condition. The loss mechanism is essentially the same as the coherent betatron resonance well-known in intense beam dynamics[*,**]. In fact, the collective motion of an ion plasma in the LPT is shown equivalent to that of a charged-particle beam traveling through an alternating-gradient focusing lattice. In the present study, we perform the direct measurement of low-order coherent oscillation modes in the LPT by detecting image currents induced on the electrodes’ surfaces. The four-rod structure of the LPT allows us to pick up feeble signals of the dipole and quadrupole oscillations of a plasma bunch. These signals are Fourier analyzed to evaluate the coherent oscillation tune at different initial ion densities. The time evolution of the coherent motion is also discussed in this paper.
* K. Moriya et al., Phys. Rev. Accel. Beams Vol.19, 114201 (2016).
** K. Ito et al., Phys. Rev. Accel. Beams Vol. 20, 064201 (2017).

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS018
About • paper received ※ 26 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019
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WEPTS022 Stability Tune Diagram of a High-Intensity Hadron Ring emittance, space-charge, lattice, betatron 3141

• H. Okamoto, K. Kojima, Y. Tokashiki

To date, the optimum operating point of a high-intensity hadron ring has been determined on the basis of the conventional incoherent picture. It is generally chosen on the tune diagram such that the so-called "incoherent tune spread" of a stored beam does not overlap with low-order "single-particle resonance" lines. We here propose a new approach to construct the stability tune diagram on the basis of the self-consistent coherent picture. The betatron resonance condition recently conjectured from one-dimensional Vlasov predictions is employed for this purpose, which predicts the existence of twice as many resonance stop bands as expected from the well-known incoherent resonance condition at high beam density *,**. The proposed general rules for the stability-chart construction are very simple and free from any model-dependent unobservables like space-charge-depressed incoherent tunes. As an example, we apply the present rules to the lattice of the rapid cycling synchrotron at J-PARC and explain why the operating bare tunes of this machine have been chosen slightly below 6.5 in both transverse directions.
* K. Ito et al., Phys. Rev. Accel. Beams 20, 064201 (2017).
** H. Okamoto and K. Yokoya, Nucl. Instrum. Meth. A 482, 51 (2002).

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS022
About • paper received ※ 09 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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WEPTS041 Coupling and Space Charge Studies at the CERN PSB optics, coupling, emittance, space-charge 3192

• F. Asvesta
NTUA, Athens, Greece
• F. Antoniou, H. Bartosik, G.P. Di Giovanni, Y. Papaphilippou
CERN, Meyrin, Switzerland

In the nominal optics of the CERN PS-Booster (PSB), the fourth order coupling resonance is excited by space charge (Montague resonance) due to the same integer tune values. This resonance can be avoided by changing the tunes to different integers. A new PSB optics is presented and emittance measurements crossing the coupling resonance for the nominal and the new optics are shown.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS041
About • paper received ※ 17 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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WEPTS042 Detailed Characterisation of the LEIR Intensity Limitations for a Pb Ion Beam emittance, simulation, injection, sextupole 3196

• Á. Saá Hernández, H. Bartosik, N. Biancacci, S. Hirlaender, D. Moreno Garcia, M. Zampetakis
CERN, Meyrin, Switzerland

The equilibrium emittance of the Pb beam in the CERN Low Energy Ion Ring (LEIR) results from the interplay of electron cooling and heating processes, as intra-beam scattering and space charge. In this paper we present the measurements of the emittance evolution as a function of intensity, working point and resonance excitation, and compare them with the simulations of the heating processes. Optimum settings for normal and skew sextupoles have been found for the compensation of resonances excited by the lattice.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS042
About • paper received ※ 18 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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WEPTS047 Space Charge Driven Resonances in the CERN PS space-charge, brightness, simulation, lattice 3216

• F. Asvesta
NTUA, Athens, Greece
• H. Bartosik, A. Huschauer, Y. Papaphilippou
CERN, Geneva, Switzerland

In the CERN Proton Synchrotron space charge driven resonances are excited around the operational working point due to the periodicity of the optics functions. In this paper, the resonances are studied using analytical methods, i.e. the evaluation of the resonance driving terms connected to the space charge potential of Gaussian distributions. Furthermore, the resonances are characterized in measurements and simulations for various beams. The beams considered are different in terms of brightness, in order to study the dependence of the resonance strength on the space charge force.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS047
About • paper received ※ 17 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019
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WEPTS053 Frequency Map Measurements at the TPS dynamic-aperture, operation, MMI, storage-ring 3240

• C.H. Chen, B.Y. Chen, J.Y. Chen, M.-S. Chiu, P.J. Chou, T.W. Hsu, B.Y. Huang, C.-C. Kuo, W.Y. Lin, Y.-C. Liu, H.-J. Tsai, F.H. Tseng
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source (TPS) has been operated for several years since it’s first light in December 2014. TPS has achieved reliable routine operation at 500 mA with more than 10 hrs beam lifetime. The dynamic aperture measurements and associated Frequency Map Analyses (FMA) at TPS reveal the beam dynamics behavior with and without insertion devices. A preliminary measurement study by using the turn-by-turn BPMs and comparison with the model simulation results will be presented in this paper.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS053
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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WEPTS057 Recent Studies of the Resonances at a Cell Tune of 0.25 Using the Ibex Paul Trap experiment, emittance, simulation, space-charge 3255

• L. Martin, S.L. Sheehy
JAI, Oxford, United Kingdom
• D.J. Kelliher
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

We use the IBEX linear Paul trap to study the resonance at a cell tune of \frac{1}{4} with both equal and unequal transverse tunes, at a range on intensities. We compare this experimental result to simulation using the PIC code Warp. We find that the experimental result differs from the simulation, which may be explained by the ion loss in the IBEX experiment, which more closely replicates a real accelerator. Knowledge of the tune corresponding to greatest beam loss is important for the design of future high intensity machines.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS057
About • paper received ※ 30 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019
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WEPTS068 A Novel S-Based Symplectic Algorithm for Tracking With Space Charge space-charge, simulation, optics, proton 3279

• J.P. Edelen, D.T. Abell, D.L. Bruhwiler, N.M. Cook, C.C. Hall, S.D. Webb

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0011340
Traditional finite-difference particle-in-cell methods for modeling self-consistent space charge introduce non-Hamiltonian effects that make long-term tracking in storage rings unreliable. Foremost of these is so-called grid heating. Particularly for studies where the Hamiltonian invariants are critical for understanding the beam dynamics, such as nonlinear integrable optics, these spurious effects make interpreting simulation results difficult. To remedy this, we present a novel symplectic spectral space charge algorithm that is free of non-Hamiltonian numerical effects and, therefore, suitable for long-term tracking studies. Results presented here include a detailed study of the solver’s performance under a range of conditions. First, we show benchmarking and convergence studies for different particle shapes and different particle distributions. Then we demonstrate the solver’s ability to preserve Hamiltonian structure by studying the formation of space-charge driven resonances using both our algorithm and traditional PIC.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS068
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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THYYPLM2 Two Orbit Operation at Bessy II - During a User Test Week injection, electron, experiment, operation 3419

• P. Goslawski, F. Andreas, F. Armborst, T. Atkinson, J. Feikes, A. Jankowiak, J. Li, T. Mertens, M. Ries, A. Schälicke, G. Schiwietz, G. Wüstefeld
HZB, Berlin, Germany

Operating a storage ring close to a horizontal resonance and manipulating the transverse non-linear beam dynamics can generate stable Transverse Resonance Island Buckets (TRIBs), which give a 2nd stable orbit in the ring. Both orbits can be populated with different electron bunch filling patterns and provide two different radiation sources to the user community. Such a machine setting has been established at BESSY II and was tested under realistic user conditions in a first ’TRIBs/Two Orbit User Test Week’ in February 2018. Results and user feedback will be discussed in this contribution.
Slides THYYPLM2 [64.754 MB]
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THYYPLM2
About • paper received ※ 14 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019
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THPMP010 Implementation of RF-KO Extraction at CNAO extraction, betatron, synchrotron, kicker 3469

• S. Savazzi, E. Bressi, G. Debernardi, L. Falbo, V. Lante, C. Priano, M. G. Pullia
CNAO Foundation, Pavia, Italy
• P. Meliga
University of Pavia, Pavia, Italy
• G. Russo
Politecnico di Torino, Torino, Italy

The National Centre for Oncological Hadrontherapy (CNAO) is a synchrotron based particle therapy facility. Both protons and carbon ions can be used for treatments. The main extraction system is based on ’amplitude-momentum selection’ driven by a betatron core, but RF-KO (Radio-Frequency Knock Out) is being implemented as an alternative extraction scheme, being more suitable for a future implementation of a ’multi energy extraction’ operation of the accelerator. With a double extraction possibility, CNAO would allow an interesting theoretical and experimental evaluation of the relative merits of the two extraction schemes. The RF deflector is already installed and the RF power generation is under commissioning. Extraction simulations and first results of the system are presented.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP010
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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THPGW047 Cylindrical Cavity Design and Particle-Tracking Simulation in Cyclotron Auto-Resonance Accelerator electron, cavity, cyclotron, acceleration 3689

• Y.T. Yuan
HUST, Wuhan, People’s Republic of China
• K. Fan
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China
• Y. Jiang
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA

The Cyclotron Auto-Resonance Accelerator (CARA) is a novel concept of accelerating continuous-wave (CW) charged-particle beams. This type of accelerator has ap-plications in environment improvement area and genera-tion of high-power microwaves. In CARA, the CW elec-tron beam follows a gyrating trajectory while undergoing the interaction with a rotating TE11-mode RF field and tapered static magnetic field. The cylindrical cavity oper-ating at TE11p-mode is adapted to accelerate electron beam. The cavity size is optimized to obtain a beam with designed energy, then a design method of the TE11p-mode acceleration cavity is described here. Moreover, regard-less of space charge effect, several particle-tracking simu-lations of CARAs are showed.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW047
About • paper received ※ 16 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019
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THPGW078 Prototyping of Brazed mm-Wave Accelerating Structures cavity, simulation, GUI, RF-structure 3764

• M. A. K. Othman, B. J. Angier, A.A. Haase, E.A. Nanni, M. R. Roux, A.V. Sy
SLAC, Menlo Park, California, USA

Funding: This work was supported by Department of Energy contract DE-AC02-76SF00515. This work was also supported by NSF grants PHY-1734015.
Advanced fabrication and prototyping of metallic RF structures play a fundamental role in advancing accelerator technologies particularly at mm-wave and THz frequencies. With the scaling of the RF structure up to these frequencies, conventional fabrication techniques do not achieve the required accuracy and tolerances. Improved manufacturing techniques including diffusion bonding, brazing or clamping split-block geometries produce high quality structures when successfully implemented. However, in most schemes the resulting gap and irregularities at the iris result in a local field enhancement which is not desirable for high-gradient operation. Development of advanced split-block braze technique for THz accelerators was required for high quality miniature accelerators. A new braze technique was developed for W-band structures to control the flow of braze alloy, enabling fabrication of the first high-gradient brazed structures at mm-wave frequencies. This fabrication process has the potential to overcome consistent fabrication defects around the cell iris. Thin spacers were used to set the final gap between blocks during the braze process; while braze foil thickness is varied with minimal impact on the resulting frequency. To demonstrate the robustness of this technique, testing after the various manufacturing steps was done to monitor and track frequency change throughout the process. This technique is further pushed to produce G-band RF structures, operating at 300 GHz.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW078
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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THPRB007 Ponderomotive Instability of Self-Excited Cavity cavity, feedback, SRF, controls 3808

• S.R. Koscielniak

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 cavity, controls, linac, coupling 3812

• S.R. Koscielniak

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 cavity, controls, coupling, linac 3816

• S.R. Koscielniak

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 cavity, controls, SRF, feedback 3820

• S.R. Koscielniak