07 Accelerator Technology Main Systems
T08 RF Power Sources
Paper Title Page
WEPME003 Two Years Experience with the Upgraded ELBE RF System Driven by 20kW Solid State Amplifier Blocks (SSPA) 2257
 
  • H. Büttig, A. Arnold, A. Büchner, M. Justus, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig, G.S. Staats, J. Teichert
    HZDR, Dresden, Germany
 
  Since January 2012 the Superconducting CW Linac ELBE is equipped and in permanent operation with four 20 kW Solid State Amplifier Blocks. The poster gives an overview on the design of the new RF system and the experience gained within the first two years of operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME003  
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WEPME004 Prediction of Severe Electron Loading of High-gradient Accelerating Structures based on Field Emission Measurements of Nb and Cu Samples 2258
 
  • S. Lagotzky, G. Müller
    Bergische Universität Wuppertal, Wuppertal, Germany
 
  Funding: The work is funded by BMBF project 05H12PX6.
Enhanced field emission (EFE) limits the performance of both superconducting and normal conducting high-gradient accelerating structures. Systematic field emission scanning microscopy and correlated SEM/EDX measurements of relevant Nb and Cu samples have revealed particulates and surface irregularities with field enhancement factors b = 10 - 90 as origin of EFE. Based on sufficient emitter statistics, an exponential increase of the emitter number density N with increasing surface field (E) was found. This allows a prediction of the EFE loading of future ILC and CLIC accelerating structures by scaling of N to relevant E and using a weighted integration over the high-field cavity surface. Accordingly, an electropolished (Ra < 300 nm) and dry-ice cleaned (DIC) TESLA-shape 9-cell 1.3 GHz Nb cavity * will still suffer from EFE at Eacc = 35 MV/m (N = 0.3 /cm² at Epeak = 70 MV/m). Moreover, a diamond-turned, chemically etched and DIC 11.2 GHz Cu structure ** will breakdown at Eacc = 100 MV/m (N = 20 /cm² at Epeak = 243 MV/m). Possible improvements, i.e. by emitter processing will be discussed.
* ILC Technical Design Report (2013)
** A. Grudiev and W. Wuensch, Proceedings of LINAC2010, Tsukuba, Japan, pp. 211 - 213
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME004  
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WEPME005 Enhanced Field Emission and Emitter Activation on Flat Dry-ice Cleaned Cu Samples 2261
 
  • S. Lagotzky, G. Müller, P. Serbun
    Bergische Universität Wuppertal, Wuppertal, Germany
  • S. Calatroni, T. Muranaka
    CERN, Geneva, Switzerland
 
  Enhanced field emission (EFE), resulting in dark currents and electric breakdowns, is one of the main gradient limitations for the CLIC accelerating structures (actual design Eacc = 100 MV/m, Epeak = 240 MV/m *). Measurements on diamond-turned, flat (Ra = 158 nm) Cu samples showed first EFE at surface fields Es = 130 MV/m. In order to reduce EFE, we have installed a commercial dry ice cleaning (DIC) system in a clean room environment (class iso 5). Accordingly, the number density of emitters (N) was significantly decreased by DIC from N = 52 /cm² to N = 12 /cm² at Es = 190 MV/m. Furthermore we have tested two diamond-turned and chemically etched (SLAC treatment, Ra = 150 nm) Cu samples after DIC resulting in EFE onset at 230 MV/m. Locally measured I(V) curves of the strongest emitters yielded field enhancement factors b = 10 – 90 (10 – 85) on the diamond-turned (chemically etched), respectively. SEM and EDX investigations of the located emission sites revealed surface defects and few particulates (Al, Ca, Si) as origin of the EFE. Moreover, strong emitter activation effects were observed. A possible breakdown mechanism based on this EFE activation will be discussed.
* A. Grudiev and W. Wuensch, Proceedings of LINAC2010, Tsukuba, Japan, pp. 211 - 213
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME005  
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WEPME006 DESIGN AND CONSTRUCTION OF A 4 KW, 500 MHZ SOLID STATE RF AMPLIFIER AT IRANIAN LIGHT SOURCE FACILITY (ILSF) 2264
 
  • A. Shahverdi, H. Ajam, H. Ghasem, Kh.S. Sarhadi
    ILSF, Tehran, Iran
 
  Solid state RF power amplifiers have been considered as an attractive candidate for providing the high power RF power required in increasing number of accelerator applications in recent years. Due to the advantages of these amplifiers and based on the successful experience done in other light sources; ILSF RF group has started R&D in design and fabrication of solid state amplifiers. Two modules based on two different LDMOS transistors have been developed successfully at 500MHz. The measured characteristics are presented and compared in this paper. Combining of 8 such modules is under test to achieve 4kW output power as the first stage of the conceptually designed combining network. This paper outlines the design concept of the different parts of the amplifiers and presents the experimental results obtained so far.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME006  
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WEPME007 Multi-Bunch Generator Cavity 2267
 
  • E.A. Savin, S.V. Matsievskiy, Ya.V. Shashkov, N.P. Sobenin
    MEPhI, Moscow, Russia
  • A.A. Zavadtsev
    Nano, Moscow, Russia
 
  The concept of the six bunch generator cell for the washers and diaphragm loaded structure (Moscow Meson Factory) power supply is proposed. The required power is 0.8 MW on the 991 MHz frequency. The high-voltage electron gun produces electron bunches and puts them into the cylindrical resonator tuned to TE02 mode and operating frequency. Bunches produces RF field that takes energy from the following bunches and then energy transfer to the accelerating structure throw the tuned coupling system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME007  
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WEPME008 72 MHz Solid-state Amplifier Power Test 2270
 
  • A.Yu. Smirnov, E.V. Ivanov, A.A. Krasnov, S.A. Polikhov, I. Řežanov
    Siemens Research Center, Moscow,, Russia
  • G.B. Sharkov
    Siemens LLC, Moscow, Russia
 
  In this paper, we present the performance of 72 MHz 18 kW RF power source developed for cyclotrons. The machine is equipped with 9 class-AB power amplifier modules (each with up to 2 kW output) based on highly reliable LDMOS transistors. The whole system is arranged inside a single 19" cabinet and has coaxial 50 Ω output. The test environment and high power measurement results are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME008  
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WEPME009 Principles for Design of High Power Pulsed Microwave Devices and Devices with Low Operating Voltage for Accelerators 2273
 
  • K.G. Simonov, A.A. Borisov, I.I. Golenitskiy, A.V. Mamontov, A.N. Yunakov
    ISTOK, Moscow Region, Russia
  • O.A. Morozov
    Research and Production Co. "MAGRATEP", Fryazino, Russia
 
  The principle of obtaining the extra-high pulsed power at significantly lower operating voltages by creating klystrons with magnetron gun; location of several such klystrons in a single solenoid with a homogeneous magnetic field and summing their output capacities is proposed. The principle of designing of high-power klystron with multi-beam magnetron gun with anode modulation and several energy outputs is proposed. The principle of designing of high-power klystron magnetron gun with multi-beam magnetron gun with control electrode modulation and several energy outputs is proposed. Are given the results of theoretical studies demonstrating the feasibility of such devices and high-power microwave systems based on them. During development of principles of obtaining an extra-high power were used the design of single-beam klystron with magnetron gun with control electrode modulation created at RPC "Istok".  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME009  
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WEPME010 Implementation of Single Klystron Working Mode at the ALBA Linac 2276
 
  • R. Muñoz Horta, J.M. Gómez Cordero, F. Pérez
    CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
 
  ALBA is a third generation synchrotron light source whose injector consists of a 100 MeV Linac and a Booster that accelerates the beam up to the full energy, 3 GeV. Two pulsed klystrons are used to feed the Linac cavities. Klystron 1 feeds the bunching section and also the first accelerating structure. Klystron 2 feeds exclusively the second accelerating structure. Recently, a S-band switching system installed in the waveguide system allows us to use also Klystron 2 to power the low-energy section and operate the Linac at lower energy, around 65 MeV. So that injection into the Booster is still possible while, in the meantime, Klystron 1 can be connected to a dummy load for reparation. Therefore, the time response after a klystron failure is improved. Details of the waveguide upgrade and the results of the ALBA Linac operated with only one klystron are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME010  
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WEPME011 2 kW Balanced Amplifier Module for a 30 kW Solid-State Pulsed RF Power Amplifier at 352 MHz 2279
 
  • A. Kaftoosian, P.J. González
    ESS Bilbao, LEIOA, Spain
 
  Design and development of a 30 kW, 352 MHz pulsed RF solid-state power amplifier to be utilized for feeding re-bunching cavities in proton linac, is in progress at ESS-Bilbao. This modular transmitter is based on in-phase combination of compact, water-cooled 2 kW RF power modules, each one consists of two combined LDMOS transistors in balanced configuration. The modules include individual bias control, measurement and supply circuits. Gate modulation is foreseen to increase efficiency in pulsed regime that is up to 3ms RF pulse width and 10% duty cycle. The 2 kW RF power module has been developed and the test results are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME011  
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WEPME012 Solid-State Amplifier Development at FREIA 2282
 
  • D.S. Dancila, A. Rydberg
    Uppsala University, Department of Engineering Sciences, Uppsala, Sweden
  • A. Eriksson, V.A. Goryashko, L.F. Haapala, R.J.M.Y. Ruber, R. Wedberg, R.A. Yogi, V.G. Ziemann
    Uppsala University, Uppsala, Sweden
 
  The FREIA laboratory is a Facility for REsearch Instrumentation and Accelerator development at Uppsala University, Sweden, constructed recently to test and develop superconducting accelerating cavities and their high power RF sources. FREIA's activity target initially the European Spallation Source (ESS) requirements for testing spoke cavities and RF power stations, typically 400 kW per cavity. Different power stations will be installed at the FREIA laboratory. The first one is based on vacuum tubes and the second on a combination of solid state modules. In this context, we investigate different related aspects, such as power generation and power combination. For the characterization of solid-state amplifier modules in pulsed mode, at ESS specifications, we implemented a Hot S-parameters measurement set-up, allowing in addition the measurement of different parameters, such as gain and efficiency. We developed also a new solid-state amplifier module at 352 MHz, using commercially available LDMOS transistors. Preliminary results show a drain efficiency of 71% at 1300 W pulsed output power.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME012  
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WEPME015 High-gradient Test Results from a CLIC Prototype Accelerating Structure: TD26CC 2285
 
  • W. Wuensch, A. Degiovanni, S. Döbert, W. Farabolini, A. Grudiev, J.W. Kovermann, E. Montesinos, G. Riddone, I. Syratchev, R. Wegner
    CERN, Geneva, Switzerland
  • A. Solodko
    JINR, Dubna, Moscow Region, Russia
  • B.J. Woolley
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
 
  The CLIC study has progressively tested prototype accelerating structures which incorporate an ever increasing number of features which are needed for a final version installed in a linear collider. The most recent high power test made in the CERN X-band test stand, Xbox-1, is a of a CERN-built prototype which includes damping features but also compact input and output power couplers, which maximize the overall length to active gradient ratio of the structure. The structure’s high-gradient performance, 100 MV/m and low breakdown rate, matches previously tested structures validating both CERN fabrication and the compact coupler design.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME015  
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WEPME016 Experience Operating an X-band High-Power Test Stand at CERN 2288
 
  • W. Wuensch, N. Catalán Lasheras, A. Degiovanni, S. Döbert, W. Farabolini, J.W. Kovermann, G. McMonagle, S.F. Rey, I. Syratchev, L. Timeo
    CERN, Geneva, Switzerland
  • J. Tagg
    National Instruments Switzerland, Ennetbaden, Switzerland
  • B.J. Woolley
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
 
  CERN has constructed and is operating a klystron-based X-band test stand, called Xbox-1, dedicated to the high-gradient testing of prototype accelerating structures for CLIC and other applications such as FELs. The test stand has now been in operation for a year and significant progress has been made in understanding the system, improving its reliability, upgrading hardware and implementing automatic algorithms for conditioning the accelerating structures. This experience is reviewed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME016  
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WEPME019 Heat Distribution Analysis of Planar Baluns for 1kW Solid-state Amplifiers and Power Combining for 1.8kW 2294
 
  • T.-C. Yu, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Y.-H. Lin, Z.K. Liu, C.H. Lo, M.H. Tsai, Ch. Wang, T.-T. Yang, M.-S. Yeh
    NSRRC, Hsinchu, Taiwan
 
  Solid-state transmitter for booster and storage ring in synchrotron would be composed of hundreds of amplifier modules. The amplifier module is biased at class AB and constructed in push-pull operation. Recent trend of amplifier module design features higher power up to 800 Watts and equipped planar balun (balance-unbalance converter) for push-pull operation. In NSRRC, the exclusive round planar design has encounter high temperature situation at kW range. Therefore, further study on this thermal condition is carried out in this study. Four types of planar balun design and two laminate materials are used for heat analysis. The typical coaxial balun is also applied on actual amplifier design. The results bring the better design with proper laminate choice and leads to acceptable thermal distribution with 1kW output power at 500MHz. Besides, for a more compact module with higher output power, the combination of two chips on the same circuit reaching 1.8kW is also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME019  
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WEPME020 Commissioning of the MICE RF System 2297
 
  • A.J. Moss, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • S.M.H. Alsari
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  • A.J. Dick, K. Ronald, D.C. Speirs, C.G. Whyte
    USTRAT/SUPA, Glasgow, United Kingdom
  • T. Stanley
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  • C.J. White
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
 
  The Muon Ionisation Cooling Experiment (MICE) is being constructed at Rutherford Appleton Laboratory in the UK. The muon beam will be cooled using multiple hydrogen absorbers then reaccelerated using an RF cavity system operating at 201MHz. This paper describes recent progress in commissioning the amplifier systems at their design operation conditions, installation and operation within the Ionisation Cooling Test Facility (ICTF) as part of the MICE project.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME020  
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WEPME021 Solid-state Pulsed Klystron Transmitters 2300
 
  • K. Schrock, C. Chipman, M.P.J. Gaudreau, B.E. Simpson
    Diversified Technologies, Inc., Bedford, Massachusetts, USA
 
  Funding: Lawrence Berkeley National Laboratory Daresbury Laboratory
Diversified Technologies, Inc. (DTI) is currently building and will deliver in early 2014 two solid-state pulsed klystron transmitters. Though not identical, the units are similar in design, and will be delivered to Lawrence Berkeley National Laboratory (LBNL) and Daresbury Laboratory in England. DTI’s goal across these two projects is to develop a complete package which can subsequently be marketed in the high peak power laboratory transmitter market. The modulator is a pulse transformer-coupled hybrid system, including ancillary klystron components (i.e., focus coil, socket) but not the actual klystron tube. Both systems employ a relatively simple modulator, consisting of an energy storage capacitor, a high voltage series switch, a step-up pulse transformer, and a passive pulse-flattening circuit. This arrangement gives an extremely flat pulse and allows the use of a moderate value of storage capacitor. The DTI switch can open or close as commanded, so the pulse width is adjusted by the gate pulse to the system.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME021  
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WEPME022 The VSL3616, CPI’s 1.3 GHz, 700 Watt CW, GaN Solid State Power Amplifier 2302
 
  • G. Solomon, D. Riffelmacher, R. Snyder, M. Tracy, T.A. Treado
    CPI, Beverley, Massachusetts, USA
 
  The VSL3616 GaN SSPA is a 1.3 GHz, 700 watt CW, liquid-cooled solid state power amplifier (SSPA). It has exceptional amplitude and phase stability and is being used to drive the VKL9130A1 IOT in CPI’s VIL410 30 kW CW IOT transmitter. The VSL3616 SSPA is configured in a 19 inch rack mount enclosure. Higher power levels can be obtained by power combining multiple VSL3616 SSPAs. The VSL3616 SSPA has been designed for very tight amplitude and phase control. The amplitude ripple and phase ripple are specified to be better than 0.05% rms and better than 0.2 degrees rms, respectively. The stability of the output power is specified to be better than 0.1% over any 20 second period of time. This paper will describe the design and operation of the VSL3616 SSPA. Results from a 1000 hour life test will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME022  
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WEPME023 VIL410, CPI’s 1.3 GHz, 25 kW CW IOT Amplifier System 2305
 
  • I. Igor, R. Army, P. Brown, S. Locke, R. Rizzo, R. Snyder, G. Solomon, M. Tracy, T.A. Treado
    CPI, Beverley, Massachusetts, USA
 
  The VIL10 Heatwave™ Inductive Output Tube (IOT) amplifier system has been developed to meet the requirements of superconducting RF accelerators. Two VIL410 systems were completed and delivered in April 2014. The VKL9130A1 IOT in the VIL410 provides up to 30 kW RF output power over a 5 MHz bandwidth centered at 1.30 GHz. It operates both CW and pulsed. The VIL410 amplifier has been designed to achieve very tight amplitude and phase control. The amplitude and phase ripple are specified to be better than 0.1% rms and better than 0.2 degrees rms, respectively. The stability of the output power is specified to be better than 0.2% over a 20 second period. In normal operation, smooth control of the output is accomplished via RF input from the low level system. The VIL410 uses CPI’s VSL3616 solid state power amplifier (SSPA) to drive the IOT. The VSL3616 is a 700 watt CW SSPA which operates at 250 watts CW in the VIL410. The VIL410 has an embedded processor that controls all internal functions of the amplifier system and interfaces directly to EPICS. The VIL410 can be operated locally using a LabView PC Host program or remotely by EPICS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME023  
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FRXAB01 Trends in RF Technology for Applications to Light Sources with Great Average Power 4065
 
  • Ch. Wang
    NSRRC, Hsinchu, Taiwan
 
  RF systems are a major part of both the capital and operating costs of contemporary light sources and directly impact their capability, reliability and availability. The RF community has been discussing for many years the best choice of CW RF power source for light sources. In the domain of great average power, the choice is among a klystron, inductive-output tube, and solid-state RF amplifier. Here we review their current development and challenges and offer a perspective from a point of view of operating a light source with high reliability and availability.  
slides icon Slides FRXAB01 [4.033 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-FRXAB01  
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