MC7: Accelerator Technology
T08 RF Power Sources
Paper Title Page
WEXXPLS1 Magnetron R&D for High Efficiency CW RF Sources of Particle Accelerators 2233
 
  • H. Wang, R.M. Nelson, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  • B.R.L. Coriton, C.P. Moeller
    GA, San Diego, California, USA
  • A. Dudas, M.L. Neubauer
    Muons, Inc, Illinois, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, DOE OS/NP STTR Grant DE-SC0013203 and DOE OS/HEP Accelerator Stewardship award 2019-2021.
The scheme of using a high efficiency magnetron to drive a superconducting or normal conducting radio frequency accelerator cavity needs not only injection phase locking but also amplitude modulation to compensate for the cavity’s microphonics, frequency change, variations of cavity voltage and beam current. To be able to do a fast and efficient modulation and to compensate the frequency pushing effect due to the anode current change, the magnetron’s magnetic field has to be trimmed by an external coil*. To facilitate this, a low eddy current magnetron body has been designed and built**. This paper will present the experimental results of such modulation on a conventional 2.45 GHz magnetron at the R&D test stand. In addition, the progresses on the injection lock test to a new 1497 MHz, 13kW magnetron prototype aimed for the CEBAF klystron replacement with newly built low level RF (LLRF) controller for the amplitude modulation will be reported. Based on these R&D results, a 915MHz, 2×75kW CW industrial heating type magnetron system is being developed to be used for the high efficiency (>80%) RF source to the electron accelerator for industrial applications.
* H. Wang, et al,THPAL145, proceedings of IPAC 2018.
** M. Neubauer, et al,THPAL042, proceedings of IPAC 2018.
 
slides icon Slides WEXXPLS1 [8.033 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXXPLS1  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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THPGW005 Recent Developments of the 520 MeV Cyclotron’s High-Power RF System at TRIUMF 3591
 
  • N.V. Avreline, Y. Bylinskii, D. Gregoire, B. Jakovljevic, R.E. Laxdal, X. Wang, B.S. Waraich, V. Zvyagintsev
    TRIUMF, Vancouver, Canada
 
  520 MeV Cyclotron’s High-Power RF System has been in the state of continuous operation for over 50 years since its commissioning. This paper describes the recent upgrades of the RF System, the main goal of which was to improve reliability. Specially, we discuss the upgrades done to the RF Transmission Line (TL), the RF Power Amplifier (PA) components and their diagnostics tools. We upgraded the structure of Intermediate Power Amplifier (IPA), installed Solid State (SS) driver and are in the process of replacing tubes with a SS option for IPA and PA.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW005  
About • paper received ※ 08 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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THPGW084 Corrections of Klystron Output Pulse in SW Accelerator Testing 3772
 
  • M.H. Nasr, S.G. Tantawi
    SLAC, Menlo Park, California, USA
 
  Accelerator testing requires a good control over the shape of the used pulse. Usually, flat or stepped square pulses are used for testing. Producing a perfectly flat output pulse from the klystron can be challenging especially for testing standing wave (SW) accelerators. SW accelerator structures reflect high power back to the klystron and no isolator can withstand the reflected power level for high gradient operation. This results in a distorted output pulse from the Klystron. We developed a modulation technique that solves this problem using a negative feedback loop. This technique can also overcome a poor modulator performance and other system errors. The pulse correction feedback was successfully implemented for high gradient SW accelerator testing at SLAC and KEK.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW084  
About • paper received ※ 24 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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THPTS006 Upgrade of the Canadian Light Source Booster RF System to Solid State 4112
 
  • J.M. Patel, D. Bertwistle, J. Stampe
    CLS, Saskatoon, Saskatchewan, Canada
  • A. Bachtior, A. Borisov, N. Pupeter
    CRE, Wuppertal, Germany
  • P. Hartmann
    DELTA, Dortmund, Germany
 
  Funding: CFI, NSERC, NRC, CIHR, the Province of Saskatchewan, WD, and the University of Saskatchewan
The Canadian Light Source synchrotron (CLS) had first light in 2004. For the last 14 years of operation we have exclusively used klystrons to provide RF power to our linac, booster, and storage ring. The klystrons represent a single point of failure for the operation of our booster and storage ring. This is especially poignant in the case of our booster ring klystron which is no longer manufactured. We have chosen to move to solid state amplifier (SSA) RF technology for its implicit high redundancy, modularity, ease of maintenance, and efficiency. Herein we review the performance parameters of our upgraded booster RF to a 100 kW 500 MHz transmitter built by Cryoelectra.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS006  
About • paper received ※ 08 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPTS038 There-Dimensional Simulation of a C-Band 32-Beam Klystron 4190
SUSPFO063   use link to see paper's listing under its alternate paper code  
 
  • Z.N. Liu, H.B. Chen, J. Shi, H. Zha
    TUB, Beijing, People’s Republic of China
 
  A 32-beam klystron working at 5.712 GHz has been designed with efficiency of 70% and output power of 3.4 MW. Core oscillations method (COM) is chosen to bunch electrons. The code KlyC is used for 1-D and 1.5-D calculation and a series of parameters are given after optimizing, including the position, frequency, R/Q, Q0 and Qe of cavities. CST/PIC is used to make the final design and coaxial cavities are used. This paper describes 1-D, 1.5-D and 3-D beam dynamics of the klystron, compares their differences, and analyses effect of these differences on efficiency.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS038  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPTS052 Beam Loss Suppression by Beam Matching in Klystron 4218
 
  • S.J. Park, Y.J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
  • S.C. Cha, D.H. Kim, D.H. Yu
    VITZRONEXTECH, Ansan-si, Gyeonggi-do, Republic of Korea
  • J.H. Hwang
    POSTECH, Pohang, Kyungbuk, Republic of Korea
 
  Funding: The work was supported by the National R&D Program (grant number: 2016R1A6B2A01016828) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT in Korea.
High power klystrons usually employ large cathodes to generate high currents which are compressed inside the gun to provide optimum beam sizes at the cavity section. We compress the beam by using electrostatic and magnetostatic focusing fields which are established by gun electrodes and external magnets respectively. The geometry of the gun elecrodes and the external magnet is carefully designed to meet the matching condition which results in scalloping-free beam. We have established a systematic design procedures to achieve the beam matching condition at arbitrary beam sizes. In this article we report on the beam-matching design and simulation results with an example case of the 80-MW S-band klystron in the Pohang Accelerator Laboratory.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS052  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPTS058 New 50 KW SSPA Transmitter for the ALBA Booster 4237
 
  • P. Solans, B. Bravo, J.R. Ocampo, F. Pérez, A. Salom
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • J.V. Balboa, I. Fernández, D. Iriarte, J. Lluch, A. Mellado, C. Rosa, F. Sierra, E. Ugarte
    BTESA, Leganés, Spain
 
  ALBA is a 3th generation 3 GeV synchrotron light source located in Barcelona and operating with users since May 2012. The IOT based transmitter for the booster cavity has been replaced by a Solid State Power Amplifier (SSPA) of 50 kW at 500 MHz in August 2018. The new transmitter is made of 96 active devices, which are divided in 12 modules of 8 transistors each one. The modules are combined in groups of four using the Gysel topology and two hybrid combiners are used for the final combining stage. The design allows the transmitter to provide enough power even when multiple transistor fails occur, in the same module or in different ones, and it also presents power supplies redundancy. These modules can be hot swapped, i.e., the module can be replaced by a spare at any time, even when the transmitter is providing power without affecting the operation. After two months of operation, the transmitter fulfills very well the design specifications regarding power, efficiency and gain; and although minor problems have arisen due to infant mortality in some components, the operation of the transmitter has never been affected due to the high redundancy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS058  
About • paper received ※ 15 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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THPTS059 Development of a 1.5 GHz, 1 KW Solid State Power Amplifier for 3rd Harmonic System of the Alba Storage Ring 4240
 
  • Z. Hazami, F. Pérez, A. Salom, P. Solans
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
 
  ALBA is the Spanish third generation synchrotron light source, located near Barcelona, in operation since 2012. In order to improve the operation, a third harmonic system has been designed for the Storage Ring in order to stretch the bunch length, and so, improve the beam life time and increase the stability current thresholds. The design of the system consist of four Higher Order Mode (HOM) damped normal conductive active cavities at 1.5 GHz*, feed with 20 kW of RF power each cavity, in order to provide the voltage of 1 MV to the electron beam. The 20 kW RF power transmitter system is based on 250 W solid state power amplifier modules added in parallel by a tree combination technique. The selected combination tree divides the 20 kW overall power per cavity in twenty 1 kW crates. This paper presents the designs of the 250 W power amplifier modules, of the splitter and of the combiner, as well as the measurement results of a 1 kW prototype crate.
* HOM Damped Normal Conducting 1.5 GHz Cavity for the 3rd Harmonic System of the ALBA Storage Ring. IPAC 2019 proceedings
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS059  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPTS063 Development of a W-Band Power Extraction Structure 4252
 
  • F. Toufexis, B. J. Angier, D. Gamzina, A. McGuire, M. Shumail, S.G. Tantawi
    SLAC, Menlo Park, California, USA
 
  Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
We are modifying the X-Band Test Accelerator at SLAC to operate as an Extreme Ultra Violet (EUV) light source*. The existing photo electron gun will be replaced by a thermionic X-Band injector which utilizes RF bunch compression. The beam is accelerated up to 129 MeV using an X-Band traveling wave structure followed by a novel high shunt impedance standing wave structure. The beam then goes through a mm-wave undulator with a period of 1.75 mm, producing EUV radiation around 13.5 nm. The undulator is powered by a W-Band decelerator structure, which extracts the RF power from the electron beam. In this work we present the mechanical design and fabrication of the 91.392 GHz decelerator structure, as well as structural characterization of its cavities using SEM and 3D microscopy.
* F. Toufexis, et al, "A Compact EUV Light Source using a mm-wave Undulator", Proceedings of IPAC17.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS063  
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPTS074 The Commission of Home-made 500MHz 80kW Solid-state Amplifier in NSRRC 4288
 
  • T.-C. Yu, F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, Y.D. Li, M.-C. Lin, Z.K. Liu, C.H. Lo, Ch. Wang, M.-S. Yeh
    NSRRC, Hsinchu, Taiwan
 
  Solid-state for high power RF application is an attracting and interesting technology which is now become popular in accelerator field. To adopt and master such technique, a 500MHz, 80kW solid-state amplifier is thus developed in NSRRC. The amplifier is consisted of 100 900W amplifier modules which are driving by identical modules. Each module contains input and output directional couplers and status monitoring circuits. To have longer life time and better performance, the RF power transistors are integrated with water cooled heat sink directly. In such way, the transistors have higher output power and better efficiency. The RF power of each module is combined through coaxial combiner while its DC power is provided by parallel connected DC power supplies which can provide better redundancy and reliability. The home-made solid-state amplifier is demonstrated to have quite high quality RF power and reliability with acceptable power combination efficiency.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS074  
About • paper received ※ 29 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPTS090 Injection Locked 1497 MHz Magnetron 4322
 
  • M.L. Neubauer, M.A. Cummings, A. Dudas, R.P. Johnson, S.A. Kahn, G.M. Kazakevich, M. Popovic
    Muons, Inc, Illinois, USA
  • R.A. Rimmer, H. Wang
    JLab, Newport News, Virginia, USA
 
  Muons, In is building an amplitude modulated phase-locked magnetron to replace the klystrons in CEBAF. To do that requires changing the magnetic field at a rate that would induce eddy currents in the standard magnetron. We report on the status of the project to make a stainless steel anode with copper elements to minimize heating while the stainless steel reduces eddy current effects. The construction of the magnetron is two months from completion, while the test stand is ready for delivery of the magnetron  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS090  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPTS091 Phase and Frequency Locked 350 MHz Magnetron 4325
 
  • M.L. Neubauer, A. Dudas, R.P. Johnson, S.A. Kahn, G.M. Kazakevich, M. Popovic
    Muons, Inc, Illinois, USA
 
  The 120kW 350 MHz magnetron is being developed for a number of RF systems, chiefly among them, Niowave’s 10 MeV accelerator. Industri-al applications of the magnetron have also been explored. The CW magnetron can be operated in the pulse mode by a novel injection locking system. We report on the status of the program and progress to date  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS091  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPTS095 High Efficiency High Power Resonant Cavity Amplifier For PIP-II 4335
 
  • M.P.J. Gaudreau, D.B. Cope, E.G. Johnson, M.K. Kempkes, R.E. Simpson, N.A. Stuart
    Diversified Technologies, Inc., Bedford, Massachusetts, USA
 
  Funding: Work funded under US DOE Grant No. DE-SC0015780
Diversified Technologies, Inc. (DTI) is developing an integrated resonant-cavity combined solid-state amplifier for the Proton Improvement Plan-II (PIP-II) at Fermilab. The prototype has demonstrated multiple-transistor combining at 70% efficiency, at 675 watts per transistor at 650 MHz. The patent pending design simplifies solid-state transmitters to create straightforward scaling to 200 kW and higher high power levels. A crucial innovation is the reliable "soft-failure" mode of operation; a failure in one or more of the transistors has negligible performance impact. This design couples the transistor drains directly to the cavity without first transforming to 50 Ohms, avoiding the circulators, cables, and connectors that would normally be required. Under an ongoing SBIR grant from the US Department of Energy, DTI designed the system to accommodate over 96 transistors in each 50 kW cavity, with minimal RF, DC, and cooling connections. By the end of the SBIR, DTI will build and demonstrate a complete 100 kW-class (~200 kW) transmitter by combining four cavity modules to show the expandability of the design to very high power levels, comparable to large VEDs.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS095  
About • paper received ※ 19 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPTS102 Radio Frequency Power Stations for ESS LINAC Spoke Section 4346
 
  • C. Pasotti, M. Cautero, T. N. Gucin
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • C.A. Martins, R.A. Yogi
    ESS, Lund, Sweden
 
  26 equivalent 400 kW Radio Frequency Power Station (RFPS) units will be provided by Elettra as part of the Italian in kind contribution to ESS. They will be installed in the LINAC "Spoke Section". Each RFPS will power a single superconducting spoke cavity in pulsed operation at 352.21 MHz. The RFPS is a complete system that operates unmanned, based on a combination of solid state and tetrode amplification’s stages. The tender specification, the RFPS main features and requested performances are reported here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS102  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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