07 Accelerator Technology
T08 RF Power Sources

Paper	Title	Page
MOPC005	352.2 MHz – 150 kW Solid State Amplifiers at the ESRF	71
	J. Jacob, G. Gautier, M.L. Langlois, J.M. Mercier ESRF, Grenoble, France
	The ESRF has ordered seven 352.2 MHz – 150 kW Solid State Amplifiers (SSA) from the French company ELTA, with a design derived from the existing SSA developed by SOLEIL. The first four SSA will be commissioned by the end of 2011 and will be connected to the two booster cavities in Winter 2012 providing in total 600 kW in 10 Hz cycles. Thanks to anti-flicker capacitor banks with a total of 3 F in the 280 V DC power supply, up to only 350 kW will be drawn from the mains as compared to 1200 kW for the former klystron transmitter. The three remaining SSA will be received in 2012 and will feed three new single cell HOM damped cavities on the storage ring. The analysis of the market had shown that an alternative to klystrons needed to be investigated to guarantee the long term operation of the ESRF. SSA can be operated with a number of RF modules lost and are therefore intrinsically highly redundant. In parallel to the production by industry of this first batch of SSA, the ESRF is developing its own amplifier modules and proposing an alternative way to combine typically hundred RF modules using a single cavity combiner.
MOPC126	High Power RF System for TRIUMF E-Linac Injector	373
	A.K. Mitra, Z.T. Ang, S. Calic, S.R. Koscielniak, R.E. Laxdal, R.W. Shanks, Q. Zheng TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	TRIUMF has been funded to build the first stage of an electron linac with a final energy of 50 MeV and 500 kW beam power. The e-linac consists of an injector section with electron gun with 650 MHz rf modulated grid, a room temperature 1.3 GHz buncher cavity, and injector cryomodule, and two main-linac cryomodules for the accelerating section to be installed sequentially. The injector module has one 9 cell cavity whereas each of the accelerating cryomodules contains two 9-cell SC cavities. The injector cryomodule will be fed by a 30 kW cw Inductive Output Tube (IOT)and the accelerating cryomodule will be powered by a cw klystron. A first goal is a beam test of the e-Linac injector to 10MeV in 2012. Installation and full rated output power tests of the IOT on a 50 ohms load have been carried out. The IOT is purchased from CPI, USA while the transmitter is sourced from Bruker BioSpin. A power coupler conditioning station utilizes the same IOT. The buncher cavity is driven from a Bruker 600W amplifier. In this paper, the conceptual design of the e-Linac rf system will be summarized and the high power rf system for the injector including IOT measurement results will be presented. SC stands for superconducting
MOPC127	Development of High RF Power Solid State Amplifiers at SOLEIL	376
	P. Marchand, M.E. El Ajjouri, R. Lopes, F. Ribeiro, T. Ruan SOLEIL, Gif-sur-Yvette, France
	In SOLEIL, 5 solid state amplifiers provide the required 352 MHz RF power: 1 x 35 kW for the booster (BO) cavity and 4 x 190 kW for the 4 superconducting cavities of the storage ring (SR). Based on a design fully developed in house, they consist in a combination of a large number of 330W elementary modules (1 x 147 in the BO and 4 x 724 in the SR) with MOSFET transistors, integrated circulators and individual power supplies. After 5 years of operation, this innovative design has proved itself and demonstrated that it was an attractive alternative to the vacuum tube amplifiers, featuring an outstanding reliability and a MTBF > 1 year. In the meantime, thanks to the acquired expertise and the arrival of the 6th generation transistors, SOLEIL has carried out developments which led to doubling the power of the elementary module (700 W at 352 MHz and 500 MHz), while improving the performance in terms of gain, efficiency and thermal stress. This approach was also extended to frequencies from the FM to L band. The increasing interest for this technology has led SOLEIL to collaborate with several other laboratories and conclude a transfer of know-how with the French company, ELTA-AREVA.
MOPC128	16 kW Upgrade of the 1.3 GHz ELBE RF-system (CW) with Solid State Amplifiers	379
	H. Büttig, A. Arnold, A. Büchner, M. Justus, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig, G.S. Staats, J. Teichert HZDR, Dresden, Germany
	The superconducting CW- LINAC of the radiation source ELBE is in permanent operation since May 2001. In 2011 an upgrade program of ELBE is in progress to support additional applications. One part of the program is to double the RF-power per cavity to at least 16 kW. We first tested a 30 kW IOT-based amplifier (Bruker /CPI) at a cavity, later two 10 kW solid state amplifiers in parallel. The best solution found is based on 10 kW Solid State Power Amplifiers (SSPA) developed by Bruker BioSpin. The poster gives an overview on the status, the activities around this RF-upgrade project and the technical specification of the “turnkey” SSPA , designed for 10 kW, 1.3 GHz and full CW-operation.
MOPC129	Compact Solid State RF-Modules for Direct Drive RF-linacs	382
	R. Irsigler, M. Back, R. Baumgartner, O. Heid, T.J.S. Hughes, M. Kaspar, T. Kluge, J. Sirtl, K. Weidner, M. Zerb Siemens AG, Erlangen, Germany
	We present a modular RF power source concept based on solid state RF-modules with novel SiC transistors. The concept offers lower cost, better reliability and reduced maintenance compared to traditional RF-source technology. No circulators are required, which makes the RF-module very compact and reliable. The SiC power transistor has a very low input capacitance and was optimized for low gate resistance to enable fast switching in the VHF range. It delivers a maximum pulsed drain saturation current of 65 A. The transistor provides at 350 V supply voltage and 150 MHz an output power of 5,6 kW at a gain of 15,8 dB. It is essential to avoid high parasitic source inductances at RF and good thermal conductivity is required for operation at high duty cycle. We have built very compact 75 x 90 mm ceramic amplifier modules using a planar interconnect technology (SIPLIT) to connect the bare die transistors to the DCB substrate. The modules have a fully symmetric push-pull topology (circlotron) with four transistors in parallel in each leg. The RF-modules delivered at 150 MHz an impressive RF output power in the range of 40 kW. Further tests at 324 MHz are planned and will be presented.
MOPC130	High Power Solid State RF Amplifier Proposal for Iran Light Source Facility (ILSF)	385
	R. safian IPM, Tehran, Iran M. Jafarzadeh ILSF, Tehran, Iran
	Solid state RF amplifiers are being considered for an increasing number of accelerator applications. Their capabilities extend from a few kW of power to several hundred kilo watts and from frequencies less than 100 MHz to above 1 GHz. This paper describes the proposed general scheme for the high power solid state RF generator of the Iran light source facility (ILSF). The maximum expected power of the generator is 200 KW which is used for driving the storage ring cavities. Similar RF generator with lower output power can be used for driving the booster cavities.
MOPC132	Influences of the Inner-conductor on Microwave Characteristics in an L-band Relativistic Backward-wave Oscillator*	388
	X.J. Ge, L. Liu, B.L. Qian, J. Zhang, H.H. Zhong National University of Defense Technology, Changsha, Kaifu District, People's Republic of China
	Funding: College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, People’s Republic of China. *gexingjun230230@yahoo.com.cn The influences of the inner-conductor on microwave characteristics in an L-band relativistic backward-wave oscillator (RBWO) are investigated theoretically and experimentally. The numerical results show that the resonance frequency decreases obviously with the increase in the inner-conductor radius. To verify the above conclusions, an L-band coaxial RBWO is investigated in detail with particle-in-cell (PIC) code. It is shown that the frequency is lowered from 1.63 GHz to 1.51 GHz when the inner-conductor radius increases from 0.5 cm to 2.5 cm. And the efficiency varies in the range of 35.4-27.7%. Furthermore, experiments are carried out at the Torch-01 accelerator. When the diode voltage is 887.6 kV and the current is 7.65 kA, the radiated microwave with frequency of 1.61 GHz, power of 2.13 GW and efficiency of 31.3% is generated. It is found that the frequency decreases from 1.64 GHz to 1.58 GHz when the inner-conductor radius increases from 0.5 cm to 1.5 cm. And the efficiency varies in the range of 31.3-29.8%.
MOPC134	Multifrequency High Power Microwave Electric-vacuum Devices	391
	K.G. Simonov, A.A. Borisov, A.V. Galdetsky, A.N. Korolev, A.V. Mamontov ISTOK, Moscow Region, Russia O.A. Morozov Research and Production Co. "MAGRATEP", Fryazino, Russia
	A new approach for the design of the multifrequency high power microwave vacuum devices is proposed. These devices provide simultaneously some output phased signals with operating frequencies ω, 2 ω, , nω while input frequency is ω. For example, it is possible obtain output power at frequencies ω and 2ω by using of double-gap output resonator tuned on two modes – sinphased mode at 2ω and antiphased mode at frequency ω. It is possible obtain power at four frequencies ω, 2ω, 3ω and 6ω by using of the two double-gap output resonators placed one inside the other. It is possible obtain power at multiple frequencies by using of the special coaxial resonator. A microwave vacuum device has been fabricated in which power was extracted at nine multiple frequencies simultaneously. The output signal has form of pulses with ultrashort duration and superhigh repetition frequency equal to the input signal frequency ω. Multifrequency high power microwave vacuum devices can be used for the development of compact accelerators of charged particles.
MOPC135	IFMIF-EVEDA RF Power System	394
	D. Regidor, A. Arriaga, J.C. Calvo, A. Ibarra, I. Kirpitchev, J. Molla, P. Méndez, A. Salom, M. Weber CIEMAT, Madrid, Spain M. Abs, B. Nactergal IBA, Louvain-la-Neuve, Belgium P.-Y. Beauvais, M. Desmons, A. Mosnier CEA/DSM/IRFU, France P. Cara Fusion for Energy, Garching, Germany S.J. Ceballos, J. de la Cruz Greenpower Technologies, Sevilla, Spain Z. Cvetkovic, Z. Golubicic, C. Mendez TTI, Santander, Spain J.M. Forteza, J.M. González, C.R. Isnardi Indra Sistemas, San Fernando de Henares, Spain D. Vandeplassche SCK-CEN, Mol, Belgium
	The IFMIF/EVEDA Accelerator Prototype will be a 9 MeV, 125 mA CW deuteron accelerator to validate the technical options for the IFMIF accelerator design. The Radiofrequency Quadrupole (RFQ), buncher cavities and Superconducting Radiofrequency Linac (SRF Linac) require continuous wave RF power at 175 MHz with an accuracy of ±1% in amplitude and ±1° in phase. Also the IFMIF/EVEDA RF Power System has to work under pulsed mode operation (during the accelerator commissioning). The IFMIF/EVEDA RF Power System is composed of 18 RF power generators feeding the eight RFQ couplers (200 kW), the two buncher cavities (105 kW) and the eight superconducting half wave resonators of the SRF Linac (105 kW). The main components of each RF power chain are the Low Level Radio Frequency system (LLRF), three amplification stages and a circulator with its load. For obvious standardization and scale economies reasons, the same topology has been chosen for the 18 RF power chains: all of them use the same main components which can be individually tuned to provide different RF output powers up to 200 kW. The studies and the current design of the IFMIF/EVEDA RF Power System are presented in this contribution.
MOPC136	The RF Power Source for the High Beta Elliptical Cavities of the ESS Linac	397
	K. Rathsman, H. Danared, R. Zeng ESS, Lund, Sweden A.J. Johansson Lund University, Lund, Sweden C. Lingwood Cockcroft Institute, Lancaster University, Lancaster, United Kingdom R.J.M.Y. Ruber Uppsala University, Uppsala, Sweden C. de Almeida Martins IST-UTL, Lisbon, Portugal
	The European Spallation Source is an intergovernmental project building a multidisciplinary research laboratory based upon the world’s most powerful neutron source. The main facility will be built in Lund, Sweden. Construction is expected to start around 2013 and the first neutrons will be produced in 2019. The ESS linac delivers 5 MW of power to the target at 2.5 GeV, with a nominal current of 50 mA. The 120 high beta elliptical cavities, which operate at a frequency of 704 MHz and accelerate protons from 600 MeV to 2.5 GeV, account for more than half of the total number of rf cavities in the ESS linac and three quarter of the total beam power needed. Because of the large number of rf power sources and the high power level needed, all the design and development efforts for the rf power source have so far been focused on this part of the accelerator. The design and development status of the rf power source is reported in this paper with emphasis on reliability, maintainability, safety, power efficiency, investment cost and production capacity.
MOPC137	Medium Power 352 MHz Solid State Pulsed RF Amplifiers for the CERN Linac4 Project	400
	J.C. Broere, J. Marques Balula CERN, Geneva, Switzerland Y. Gomez LPSC, Grenoble Cedex, France M. Rossi DBE, Padova, Italy
	Economic, modular and highly linear pulsed RF amplifiers have recently been developed to be used for the three Buncher cavities in the CERN Linac4. The amplifiers are water cooled and can provide up to 33 kW pulsed RF power, 1.5 msec pulse length and 50 Hz repetition rate. Furthermore a 60 kWatt unit is under construction to provide the required RF Power for the Debuncher cavity. The concept is based on 1.2 kW RF power modules using the latest 6th generation LDMOS technology. For integration into the CERN control environment the amplifiers have an internal industrial controller, which will provide easy control and extended diagnostic functions. This paper describes the construction, performance, including linearity, phase stability and EMC compliance tests.
MOPC138	Practical Test of the Linac4 RF Power System	403
	N. Schwerg, O. Brunner CERN, Geneva, Switzerland
	Linac4 is a linear accelerator for negative Hydrogen ions which will replace the old Linac2 as injector for the CERN accelerators. Its higher energy of 160 MeV will increase the beam intensity in the downstream machines. The normal-conducting accelerating structures are housed in a 100 m long tunnel which will be connected to the existing chain of accelerators and can be extended into a new injector chain. The high RF power for the Linac4 accelerating structures will be generated by thirteen 1.3 MW klystrons, previously used for the CERN LEP accelerator, and six new klystrons of 2.8 MW all operating at a frequency of 352.2 MHz. The re-use of existing LEP equipment, space limitations in the installation and tight phase and amplitude constraints pose a number of challenges for the integration of the RF power system. The power distribution scheme features a folded magic-tee feeding the power from a 2.8 MW klystron to two LEP circulators. We present first results from the Linac4 test place, validating the approach and the used components as well as reporting on the klystron re-tuning activities.
MOPC140	Phase and Frequency Locked Magnetrons for SRF Sources	406
	M.L. Neubauer, M.A.C. Cummings, A. Dudas, R.P. Johnson, R. Sah Muons, Inc, Batavia, USA A. Moretti, M. Popovic Fermilab, Batavia, USA
	Typically, high power sources for accelerator applications are multi-megawatt microwave tubes that may be combined together to form ultra-high-power localized power stations. The RF power is then distributed to multiple strings of cavities through high power waveguide systems which are problematic in terms of expense, efficiency, and reliability. Magnetrons are the lowest cost microwave source in dollars/kW, and they have the highest efficiency (typically greater than 85%). However, the frequency stability and phase stability of magnetrons are not adequate, when magnetrons are used as power sources for accelerators. Novel variable frequency cavity techniques have been developed which will be utilized to phase and frequency lock magnetrons, allowing their use for either individual cavities, or cavity strings. Ferrite or YIG (Yttrium Iron Garnet) materials will be attached in the regions of high magnetic field of radial-vaned, π−mode structures of a selected ordinary magnetron. The microwave characteristics of several materials have been tested with magnetic fields to control the frequency of the magnetron. These results will be presented and an optimum material chosen.
MOPC142	25 Year Performance Review of the SLAC 5045 S-Band Klystron	409
	A. Jensen, A.S. Beebe, M.V. Fazio, A.A. Haase, E.N. Jongewaard, C. Pearson, D.W. Sprehn, A.E. Vlieks, L.E. Whicker SLAC, Menlo Park, California, USA
	Funding: This work was supported by the U.S. Department of Energy under contract DE-AC03-76SF00515. The SLAC 5045 S-band klystron has proven to be a remarkably reliable high peak power tube. Originally developed in the 1980’s as an upgraded RF power source for the Stanford Linear Collider, it has continually powered the SLAC linac in support of numerous programs in particle physics and photon science. The large number of tubes built and operated (more than 800) coupled with accumulated running statistics over the last 25+ years represents an unprecedented wealth of operational experience for high pulse power klystrons in accelerator applications. Mean time between failures has continued to rise during this period and is frequently in excess of 100,000 hours during the last several years. Lifetime statistics as well as some important failure modes are presented and examined here.
MOPC143	A Reduced Gradient Output Design for SLAC's XL4 X-Band Klystron	412
	A. Jensen, C. Adolphsen, A.E. Candel, M.V. Fazio, E.N. Jongewaard, D.W. Sprehn, A.E. Vlieks, F. Wang SLAC, Menlo Park, California, USA
	Funding: This work was supported by the U.S. Department of Energy under contract DE-AC03-76SF00515. X-band klystron work began at SLAC in the mid to late 1980's to develop high frequency (4 times the SLAC S-band klystron), high power RF sources for the linear collider designs under consideration at that time. This work culminated in the current workhorse X-band RF source, the XL4. To date 26 XL4 tubes have been built. The XL4 4-cell disk loaded traveling wave output structure has a high operating gradient. A new 6-cell structure has been designed to reduce breakdown and to further improve the klystron's robustness. Initial simulations show the 6-cell design reduces the gradient roughly 25% and that the structure is stable. A physical XL4 will be retrofitted with the new output cavity and hot tested in the near future.
MOPC156	Operation Test of Distributed RF System with Circulator-less Waveguide Distribution in S1-Global Project at STF/KEK	448
	T. Matsumoto, M. Akemoto, D.A. Arakawa, S. Fukuda, H. Honma, E. Kako, H. Katagiri, S. Matsumoto, H. Matsushita, S. Michizono, T. Miura, H. Nakajima, K. Nakao, T. Shidara, T. Takenaka, Y. Yano, M. Yoshida KEK, Ibaraki, Japan
	Distributed RF System (DRFS) is one candidate for a single main linac tunnel design of International International Linear Collider (ILC). In the DRFS, more than ten 800-kW klystrons having a modulating anode are operated by a common DC power and a modulation anode modulator. Each klystron feeds its power into two superconducting cavities and its waveguide distribution system is configured without circulators. This DRFS consists of four SC cavities, two klystrons and a modulator was demonstrated in S1-Global project. The results of circulator-less operation in the DRFS will be reported.
THOBB01	Evaluation of Performance, Reliability, and Risk for High Peak Power RF Sources from S-band through X-band for Advanced Accelerator Applications	2882
	M.V. Fazio, C. Adolphsen, A. Jensen, C. Pearson, D.W. Sprehn, A.E. Vlieks, F. Wang SLAC, Menlo Park, California, USA M.V. Fazio LANL, Los Alamos, New Mexico, USA
	Historically linear accelerator development and the choice of frequency have been driven by the availability of RF power sources. This is also true at the present time and is particularly significant as new accelerators are being conceived and planned over a wide frequency range for FEL light sources and other applications. This paper evaluates the current state of the technology for high peak power RF sources from S-band through X-band including reliability and the facility risk incurred for applications demanding high availability and decades-long operation.
	Slides THOBB01 [2.326 MB]