IPAC2011 - List of Keywords (cavity)

Paper	Title	Other Keywords	Page
MOYBA01	Present Status of the ILC Project and Developments	linac, linear-collider, collider, electron	16
	M.C. Ross Fermilab, Batavia, USA N.J. Walker DESY, Hamburg, Germany A. Yamamoto KEK, Ibaraki, Japan
	Funding: FNAL is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The Technical Design of the ILC Project will be finished in late 2012. The Technical Design Report will include a description of the updated design, with a cost estimate and a project plan, and the results of R & D done in support of the ILC. Results from directed ILC R & D are used to reduce the cost and risk associated with the ILC design. We present a summary of key challenges and show how the global R & D effort has addressed them. The most important activity has been in pursuit of very high gradient superconducting RF linac technology. There has been excellent progress toward the goal of practical industrial production of niobium sheet-metal cavities with gradient performance in excess of 35 MV/m. In addition, three purpose-built beam test facilities have been constructed and used to study and demonstrate high current linac performance, electron-cloud beam dynamics and precision beam control. The report also includes a summary of component design studies and conventional facilities cost optimization design studies.
	Slides MOYBA01 [9.755 MB]

MOOCA01	Production and Testing Experience with the SRF Cavities for the CEBAF 12 GeV Upgrade	cryomodule, HOM, SRF, higher-order-mode	26
	A. Burrill, G.K. Davis, F. Marhauser, C.E. Reece, A.V. Reilly, M. Stirbet JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The CEBAF recirculating CW electron linear accelerator at Jefferson Lab is presently undergoing a major upgrade to 12 GeV. This project includes the fabrication, preparation, and testing of 80 new 7-cell SRF cavities, followed by their incorporation into ten new cryomodules for subsequent testing and installation. In order to maximize the cavity Q over the full operable dynamic range in CEBAF (as high as 25 MV/m), the decision was taken to apply a streamlined preparation process that includes a final light temperature-controlled electropolish of the rf surface over the vendor-provided bulk BCP etch. Cavity processing work began at JLab in September 2010 and will continue through December 2011. The excellent performance results are exceeding project requirements and indicate a fabrication and preparation process that is stable and well controlled. The cavity production and performance experience to date will be summarized and lessons learned reported to the community.
	Slides MOOCA01 [4.376 MB]

MOOCA03	Updates to the International Linear Collider Damping Rings Baseline Design	lattice, damping, electron, positron	32
	S. Guiducci, M.E. Biagini INFN/LNF, Frascati (Roma), Italy G. Dugan, M.A. Palmer, D. L. Rubin CLASSE, Ithaca, New York, USA J. Gao, D. Wang IHEP Beijing, Beijing, People's Republic of China M.T.F. Pivi, Y. Sun SLAC, Menlo Park, California, USA J. Urakawa KEK, Ibaraki, Japan
	A new baseline design for the International Linear Collider (ILC) damping rings has been adopted which reduces the ring circumference to 3.2 km from 6.4 km. This design change is associated with a revised plan to operate the ILC with one half the beam current originally specified in the ILC Reference Design Report. We describe the new layout and lattice that has been developed for the shorter ring. In addition, we discuss features of the new design that will allow operation at a 10Hz repetition rate which is twice the rate specified for baseline operation. Finally, we examine the implications for restoring operation with the originally specified beam current while maintaining the smaller ring circumference.
	Slides MOOCA03 [2.381 MB]

MOODA01	Experience with the Cornell ERL Injector SRF Cryomodule during High Beam Current Operation	HOM, SRF, cryomodule, damping	35
	M. Liepe, D.L. Hartill, G.H. Hoffstaetter, S. Posen, P. Quigley, V. Veshcherevich CLASSE, Ithaca, New York, USA
	Funding: Supported by NSF award DMR-0807731 Cornell University has developed and fabricated a SCRF injector cryomodule for the acceleration of high current, low emittance CW beams. This cryomodule is based on superconducting RF technology with five 2-cell SRF cavities operated in CW mode. Strong Higher-Order-Mode (HOM) damping and high power RF input couplers support accelerating beam currents of tens of mA. The cryomodule is currently under extensive testing in the Cornell ERL injector prototype with CW beam currents exceeding 25 mA. This paper gives an overview of the experience gained during the high beam current operation of the cryomodule, with a focus on the intrinsic cavity quality factors, input coupler performance, and HOM damping.

MOODA02	S1-Global Module Tests at STF/KEK	cryomodule, SRF, feedback, linac	38
	D. Kostin, K. Jensch, L. Lilje, A. Matheisen, W.-D. Möller, P. Schilling, M. Schmökel, N.J. Walker, H. Weise DESY, Hamburg, Germany C. Adolphsen, C.D. Nantista SLAC, Menlo Park, California, USA M. Akemoto, S. Fukuda, K. Hara, H. Hayano, N. Higashi, E. Kako, H. Katagiri, Y. Kojima, Y. Kondo, T. Matsumoto, H. Matsushita, S. Michizono, T. Miura, H. Nakai, H. Nakajima, K. Nakanishi, S. Noguchi, N. Ohuchi, T. Saeki, M. Satoh, T. Shidara, T. Shishido, T. Takenaka, A. Terashima, N. Toge, K. Tsuchiya, K. Watanabe, S. Yamaguchi, A. Yamamoto, Y. Yamamoto, K. Yokoya KEK, Ibaraki, Japan T.T. Arkan, S. Barbanotti, M.A. Battistoni, H. Carter, M.S. Champion, A. Hocker, R.D. Kephart, J.S. Kerby, D.V. Mitchell, T.J. Peterson, Y.M. Pischalnikov, M.C. Ross, W. Schappert, B.E. Smith Fermilab, Batavia, USA A. Bosotti, C. Pagani, R. Paparella, P. Pierini INFN/LASA, Segrate (MI), Italy
	S1-Global collaborative effort of INFN, DESY, FNAL, SLAC and KEK, recently successfully finished at KEK as a part of ILC GDE, is an important milestone for the ILC. International collaboration of three regions, Asia, North America and Europe, proved to be efficient on the construction and cold tests of the accelerating module consisting of 8 SRF cavities; 2 from FNAL, 2 from DESY and 4 from KEK. Three different cavity tuning systems were tested together with two types of high power couplers. The module was cooled down three times which enabled extensive high power tests with cavities, performance limits investigation, Lorentz force detuning tests, simultaneous multiple cavities operation and other activities such as an operation test of distributed RF scheme with low level RF feedback. The results of this S1-Global module test are presented and discussed.
	Slides MOODA02 [2.982 MB]

MOODA03	First Characterization of a Fully Superconducting RF Photoinjector Cavity	cathode, laser, linac, solenoid	41
	A. Neumann, W. Anders, R. Barday, A. Jankowiak, T. Kamps, J. Knobloch, O. Kugeler, A.N. Matveenko, T. Quast, J. Rudolph, S.G. Schubert, J. Völker HZB, Berlin, Germany P. Kneisel JLAB, Newport News, Virginia, USA R. Nietubyc The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock, Poland J.K. Sekutowicz DESY, Hamburg, Germany J. Smedley BNL, Upton, Long Island, New York, USA V. Volkov BINP SB RAS, Novosibirsk, Russia G. Weinberg FHI, Berlin, Germany I. Will MBI, Berlin, Germany
	As a first step towards a high brightness, high average current electron source for the BERLinPro ERL a fully superconducting photo-injector was developed by HZB in collaboration with JLab, DESY and the A. Soltan Institute. This cavity-injector ensemble is made up of a 1.6-cell superconducting cavity with a superconducting lead cathode deposited on the half-cell backwall. A superconducting solenoid is used for emittance compensation. This system, including a diagnostics beamline, has been installed in the HoBiCaT facility to serve as a testbed for beam dynamics studies and to test the combination SRF cavity and superconducting solenoid. This paper summarizes the characterization of the cavity in this configuration including Q measurements, dark current tests and field-stability analyses.
	Slides MOODA03 [10.343 MB]

MOOCB02	Commissioning and Performance of the Beam Monitor System for XFEL/SPring-8 “SACLA”	electron, undulator, bunching, FEL	47
	Y. Otake, C. Kondo, H. Maesaka RIKEN Spring-8 Harima, Hyogo, Japan H. Ego, S. Matsubara, T. Matsumoto, T. Sakurai, H. Tomizawa, K. Yanagida JASRI/SPring-8, Hyogo-ken, Japan S.I. Inoue SES, Hyogo-pref., Japan
	The construction of a beam monitor system for XFEL/SPring 8 “SACLA” was completed. The system was developed to realize a spatial resolution of less than 3 um to align a beam orbit for an undulator section with about 100 m long and a temporal resolution to measure bunch lengths from 1 ns to 30 fs to maintain a constant peak beam current conducting stable SASE lasing. The system principally comprises cavity type beam position monitors (BPM), current monitors (CT), screen monitors (SCM) and bunch length measurement instruments, such as an rf deflector and CSR detectors. Commissioning of SACLA started from March 2011, and the monitors performed sufficient roles to tune beams for the lasing. The achieved over-all performances of the system including DAQ are: the BPM have spatial resolution of 300 nm, the bunch length monitors observe bunch lengths from 1ns in an injector with velocity bunching to less than 30 fs after three-stage bunch compressors. The less than a 3 um spatial resolution of the SCM was also confirmed in practical beam operation. By these fulfilled performances, the stable lasing of SACLA will be achieved. This report describes commissioning, performance of the system.
	Slides MOOCB02 [7.516 MB]

MOODB02	RF Modeling Plans for the European Spallation Source	HOM, electron, beam-losses, linac	56
	S. Molloy, M. Lindroos, S. Peggs ESS, Lund, Sweden R. Ainsworth Royal Holloway, University of London, Surrey, United Kingdom R.J.M.Y. Ruber Uppsala University, Uppsala, Sweden
	The European Spallation Source (ESS) will be the world's most powerful next generation neutron source. The ESS linac is designed to accelerate highly charged bunches of protons to a final energy of 2.5 GeV, with a design beam power of 5 MW, for collision with a target used to produce the high neutron flux. In order to achieve this several stages of RF acceleration are required, each using a different technology. The high beam current and power require a high degree of control of the accelerating RF, and the specification that no more than 1 W/m of losses will be experienced means that the excitation and decay of the HOMs must be very well understood. Experience at other high power machines also implies that an understanding of the generation and subsequent trajectories of any field-emitted electrons should be understood. Thermal detuning of the HOM couplers due to multipacting is a serious concern here. This paper will outline the RF modeling plans - including the construction of mathematical models, simulations of HOMs, and multipacting - during the current Accelerator Design Update phase, and will discuss several of the more important issues for ESS.
	Slides MOODB02 [48.641 MB]

MOPC004	352.2 MHz HOM Damped Normal Conducting ESRF Cavity: Design and Fabrication	HOM, coupling, vacuum, storage-ring	68
	V. Serrière, A.K. Bandyopadhyay, D. Boilot, L. Goirand, J. Jacob, B. Ogier, A. Triantafyllou ESRF, Grenoble, France
	Funding: This work, carried out within the framework of the ESRFUP project, has received research funding from the EU Seventh Framework Programme, FP7. The ongoing ESRF upgrade included an option for an increase of the storage ring current from 200 to 300 mA, which has been tested successfully with the existing RF system. At this current level the HOM tuning of the existing five-cell copper cavities becomes extremely delicate and in view of a future reliable operation in user mode, new HOM free normal conducting cavities were developed at the ESRF. The design is based on the existing BESSY/ALBA cavity. However, several substantial modifications have been implemented and different fabrication processes elaborated to improve the design. Three operational prototypes will be delivered by three manufacturers in the coming months and will be fully tested on the ring. Although the 300 mA option has finally not been retained for the first phase of the ESRF upgrade, the aim is now to validate the new cavity design for a possible later increase in current.

MOPC005	352.2 MHz – 150 kW Solid State Amplifiers at the ESRF	booster, klystron, HOM, power-supply	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.

MOPC006	A Coupled RFQ-IH Combination for the Neutron Source FRANZ	rfq, DTL, coupling, proton	74
	M. Heilmann, O. Meusel, D. Mäder, U. Ratzinger, A. Schempp IAP, Frankfurt am Main, Germany
	Funding: HIC for FAIR The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum is driven by a 2 MeV proton linac consisting of a 4-rod-radio-frequency-quadrupol (RFQ) and an 8 gap IH-DTL structure. RFQ and IH cavity will be powered by only one radio frequency (RF) amplifier to reduce costs. The RF-amplifier of the RFQ-IH combination is coupled into the RFQ. Internal inductive coupling along the axis connects the RFQ with the IH cavity ensuring the required power transition as well as a fixed phase relation between the two structures. The main acceleration of 120 keV up to 2.03 MeV will be reached by the RFQ-IH combination with 175 MHz and at a total length of 2.3 m. The losses in the RFQ-IH combination are about 200 kW.

MOPC007	Cold Photocathode RF Gun	gun, vacuum, cathode, cryogenics	77
	V. Vogel, K. Flöttmann, S. Schreiber DESY, Hamburg, Germany
	Heating and thermal expansion in the normal conductivity RF-photo electron gun, are the main limitations to achieve high accelerating gradient and consequently a low emittance beam. Some pure materials show a significant increase in thermal conductivity with a small coefficient of temperature expansion at temperatures around 20 degrees Kelvin. Possible materials are Molybdenum, Iridium or Tungsten. However, machining of these materials is very difficult. Therefore we propose a simplified shape for an L-band RF gun. We expect to achieve a significant increase in gradient for similar RF powers as used in the present DESY RF-gun. On the other hand, it would also be possible to increase the duty cycle keeping a moderate gradient. In this report we discuss one possible design of an RF-gun using hard metals and present simulations on thermal properties.

MOPC010	Phase-Modulation SLED Operation Mode at Elettra	linac, LLRF, klystron, target	83
	C. Serpico, P. Delgiusto, A. Fabris, F. Gelmetti, M.M. Milloch, A. Salom, D. Wang ELETTRA, Basovizza, Italy
	FERMI@Elettra is the soft X-ray, fourth generation light source facility at the Elettra Laboratory in Trieste, Italy. It is based on a seeded FEL, driven by a normal conducting linac that is presently expected to operate at 1.5 GeV. The last seven backward traveling wave structures have been equipped with a SLED system. Due to breakdown problems inside the sections, that was the result of high peak fields generated during conventional SLED operation, the sections experienced difficulties in reaching the desired gradients. To lower the peak field and make the compressed pulse “flatter”, phase-modulation of the SLED drive power will be implemented. A description of the phase modulation of the drive power and the results achieved will be reported in the following paper.

MOPC014	RF Processing of L-band RF Gun for KEK-STF	gun, cathode, laser, solenoid	92
	M. Kuriki, H. Iijima, Y.M. Masumoto HU/AdSM, Higashi-Hiroshima, Japan H. Hayano, H. Sugiyama, J. Urakawa, K. Watanabe KEK, Ibaraki, Japan G. Isoyama, R. Kato ISIR, Osaka, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan Y. Takahashi Sokendai, Ibaraki, Japan
	Funding: This work is supported by MEXT Quantum Beam Technology Program, KEK Promotion of collaborative research programs in universitie. KEK STF (Superconducting Test Facility) is established for developing super-conducting accelerator technology for ILC (International Linear Collider). At KEK-STF, accelerator operation with a beam loading is planned in 2013. An electron injector based on L-band Photo-cathode RF gun is now being developed. A L-band RF gun designed by DESY and fabricated by FNAL has been placed in KEK-STF and RF processing was carried out. The results of the RF processing and status of STF injector will be presented.

MOPC015	S-band Vacuum Isolator and Circulator for Injector System of SPring-8 Linac	vacuum, linac, insertion, injection	95
	T. Taniuchi, H. Hanaki, S. Suzuki JASRI/SPring-8, Hyogo-ken, Japan A. Miura, K. Shinohara, S. Tsuruoka Nihon Koshuha Co. Ltd, Yokohama, Japan
	A pressurized sulfur hexafluoride (SF6) waveguide system at an injector section of SPring-8 linac, will be replaced with a vacuum waveguide system in order to renew aged equipments and improve a phase stability. For this renewal, RF isolator and a circulator operated in vacuum, are newly developed. High power RF test for these components were performed and a good result for RF and vacuum characteristics were obtained.

MOPC016	Development of a New RF Accelerating Cavity for J-PARC Ring Accelerator	simulation, impedance, ion, controls	98
	Y. Morita, T. Kageyama KEK, Ibaraki, Japan J. Kameda ICRR, Chiba, Japan S. Yamashita ICEPP, Tokyo, Japan
	Funding: Japan Society for the Promotion of Science (JSPS) To enhance the beam power delivered by the J-PARC* ring accelerators, upgrading the accelerating cavities is indispensable. In particular, long term stable operation of the present cavities for the RCS is one of the important issues. Currently, the cavities are loaded with FINEMET* cores cooled by water, where every core is coated with glass cloth and epoxy resin for waterproof. However, it was reported that some of the cores were damaged by thermal stress. We are developing a new cavity loaded with multi ring core modules. Each core module consists of three ring cores concentrically arranged and sandwiched between two glass epoxy plates with flow channels grooved. The ring cores without waterproof coating are cooled by the turbulent flow of a chemically inert liquid (Fluorinert), since FINEMET is subject to corrosion in water. We have designed and built a high power prototype cavity loaded with a single core module, then carried out low level measurement and high power test. Finally, the cavity has been stably operated up to an average power loss of 10 kW per core module, which is 1.7 times higher than that for the present RCS cavity. Japan Proton Accelerator Research Complex Rapid-Cycling Synchrotron **FINEMET is an iron-based magnetic alloy produced by Hitachi Metals, Ltd..

MOPC017	Thermal Analyses of an RF Input Coupler for the IFMIF/EVEDA RFQ Linac	rfq, coupling, linac, beam-transport	101
	S. Maebara JAEA, Ibaraki-ken, Japan
	In the design of prototype RFQ linac for the IFMIF/EVEDA Project, a coupled cavity type of RFQ, which has a longitudinal length of 9.78m, was proposed to accelerate deuteron beam up to 5MeV. The operation frequency of 175MHz was selected to accelerate a large current of 125mA in CW mode. The driving RF power of 1.28 MW by 8 RF input couplers has to be injected to the RFQ cavity. As the RF input coupler design, RF losses including a loop antenna and an RF vacuum window, based on a 6 1/8 inch co-axial waveguide were calculated. In this conference, these results and thermal analysis results in CW operation mode will be presented in details.

MOPC019	Condition of MA Cut Cores in the RF Cavities of J-PARC Main Ring after Several Years of Operation	impedance, resonance, ion, synchrotron	107
	M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-mura, Japan E. Ezura, K. Hasegawa, K. Takata KEK, Tokai, Ibaraki, Japan K. Hara, C. Ohmori, M. Toda, M. Yoshii KEK/JAEA, Ibaraki-Ken, Japan T. Sato, M. Yamamoto JAEA, Ibaraki-ken, Japan
	J-PARC 3 GeV RCS and 50 GeV Synchrotron (MR) employ RF cavities loaded with Magnetic Alloy (MA) cores to generate a high field gradient. The RF cavities in RCS use MA un-cut cores. On the other hand, the RF cavities in MR employ MA cut cores to increase the Q-value from 0.6 to 26. We observed the impedance reductions of all MR RF cavities during several years operation. Opening the RF cavities, we found that the impedance reductions were resulting from corrosion on the cut and polished surfaces of MA cores. Before installation of the RF cavities, we had 1000 and 2000 hours long tests at a test stand. We didn't observe the impedance reduction related to the corrosion on the MA core cut surfaces at the test stand. The only difference between the test stand and MR is the quality of cooling water. The MR cooling water contains copper ions for example from copper hollow conductors of the main magnets. We report the influence of the copper ions to the corrosion on the MA core cut surface. We also show plans how to solve the issue of MA core cut surface corrosion.

MOPC020	Development of an S-band Multi-cell Accelerating Cavity for RF Gun and Booster Linac	gun, booster, linac, electron	110
	T. Aoki, K. Sakaue, M. Washio RISE, Tokyo, Japan A. Deshpande SAMEER, Mumbai, India M.K. Fukuda, N.K. Kudo, T. Takatomi, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	Funding: Work supported by JST Quantum Beam Program We have been developing a photocathode rf gun. The rf gun with multi cell can produce a high energy electron beam, so it may be used for numerous applications such as medicine and industry. At Laser Undulator Compact X-ray source (LUCX), we have developed a compact X-ray source based on inverse Compton scattering. Using a multi cell rf gun will make possible for the X-ray source to use for such applications. S-band 3.5 cell rf electron gun which is 20 cm long can produce more than 10 MeV electron beam. According to the simulation, it is said that the emittance of 3.5 cell rf gun is as low as that of 1.6 cell rf gun. The electromagnetic design has been performed with the code SuperFish, and the particle tracing by Parmela. The new rf gun is already installed and produced a high quality electron beam with energy of more than 10 MeV. As a consequence of the substantial efforts of developing rf cavity, we decide to make a compact RF accelerating structure with more cell for achieving a smaller system. The measurement results of using the 3.5 cell rf gun, the design of 12 cell booster cavity, and current status of 12 cell cavity manufacturing will be presented at the conference.

MOPC024	Construction Status of the CPHS RFQ at Tsinghua University	rfq, quadrupole, dipole, vacuum	122
	Q.Z. Xing, Y.J. Bai, J.C. Cai, C. Cheng, L. Du, T. Du, X. Guan, Q. Qiang, X.W. Wang, Z.F. Xiong, S.Y. Yang, H.Y. Zhang, S.X. Zheng TUB, Beijing, People's Republic of China J.H. Billen TechSource, Santa Fe, New Mexico, USA W.Q. Guan, Y. He, J. Li NUCTECH, Beijing, People's Republic of China J. Stovall CERN, Geneva, Switzerland L.M. Young AES, Medford, NY, USA
	Funding: Work supported by the “985 Project” of the Ministry of Education of China. We present, in this paper, the construction status of a Radio Frequency Quadrupole (RFQ) accelerator for the Compact Pulsed Hadron Source (CPHS) at Tsinghua University. The 3-meter-long RFQ will deliver 3 MeV protons to the downstream Drift Tube Linac (DTL) with the peak current of 50 mA, pulse length of 0.5 ms and beam duty factor of 2.5%. The RFQ has been mechanically separated into three sections. A ball-end mill, instead of a forming cutter, is adopted to machine the vane tip due to its varying radius of curvature. The precision of the numerically controlled milling machine has been verified by machining test pieces of aluminum and copper. Fine machining of the vanes was completed in July, 2011. The pre-braze tuning was completed at the beginning of this August.

MOPC026	MA Cavity for HIRFL-CSR	impedance, simulation, plasma, radio-frequency	125
	L.R. Mei, Z. Xu, Y.J. Yuan, H.W. Zhao IMP, Lanzhou, People's Republic of China
	To meet the requirements of conducting high energy density physics and plasma physics research at HIRFL-CSR. The higher accelerating gap voltage was required. A magnetic alloy (MA)-core loaded radio frequency (RF) cavity which can provide higher accelerating gap voltage has been studied in Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS), Lanzhou. To select proper MA material to load the RF cavity, measurement for MA cores has been conducted. The MA core with higher shunt impedance and lower than 1 quality factor (Q value) should be selected. The theoretical calculation and simulation for the MA-core loaded RF cavity can be consistent with each other well. Finally 1000kW power was needed to meet 50-kV accelerating gap voltage by calculation.

MOPC031	Performance of a 13 MHz Cavity for an RF Implanter at PEFP*	coupling, ion, ion-source, simulation	136
	T.A. Trinh UST, Daejeon, Republic of Korea Y.-S. Cho, J.-H. Jang, D.I. Kim, H.S. Kim, H.-J. Kwon, B.-S. Park, K.T. Seol KAERI, Daejon, Republic of Korea
	Funding: This work is supported by the Ministry of Education, Science and Technology of the Korean Government A 13 MHz - normal conducting cavity for an rf implanter has been successfully developed at PEFP (Proton Engineering Frontier Project). It consists of an inductive coil, accelerating electrodes and a ground electrode for the inductor. Quality factor of 2074 and critical coupling were achieved at resonant frequency of 12.658 MHz. Rf power of 1 kW was forwarded to the cavity without any spark in the cavity. Beam test was then carried out with a 27 keV helium beam generated from a Duoplasmatron ion source. The results showed that the helium beam was accelerated to final energy of 120 keV with energy spread of 1%. Detail experiments and results are addressed in this presentation.

MOPC033	The Status of a 1.6-cell Photocathode RF Gun at PAL	gun, klystron, emittance, cathode	142
	M.S. Chae, J.H. Hong, I.S. Ko, Y.W. Parc POSTECH, Pohang, Kyungbuk, Republic of Korea S.J. Park PAL, Pohang, Kyungbuk, Republic of Korea
	The RF power conditioning of the photocathode RF gun with four holes at the side of the full cell named as 'Pohang gun' is in progress. The first goal of the conditioning is the operation of the gun with RF pulse width of 1.5 μm, repetition rate of 30 Hz, field gradient at the cathode of 130 MV/m. We operated the RF gun successfully with the conditions within last few months. It was first operational experience with such conditions in PAL. Now we have a plan to operate RF gun with higher repetition rate up to 60 Hz.

MOPC035	Design and Machine Features of 2.2-m C-band Accelerating Structure	accelerating-gradient, linac, vacuum, electron	148
	C.H. Yi, M.-H. Cho, S.H. Kim, H. Lee POSTECH, Pohang, Kyungbuk, Republic of Korea W. Namkung PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: This work is partly supported by the MEST, Korea and POSTECH BK21 Program. And this work was supported by the Korea Student Aid Foundation (KOSAF) grant funded by the Korea government. A compact linac system is designed using a longer accelerating column in a C-band linac. It reduces the total number of RF units for the given linac beam energy and results in the cost-effective use of RF powers. For the 10 GeV PAL-XFEL project, a C-band accelerating column of 2.2-m long is investigated, which is 22% longer than 1.8-m for the SACLA at SPring-8. The detailed RF and thermal characteristics are presented by an analytic model.

MOPC036	Design of RF Cavity for Compact 9 MeV Cyclotron	cyclotron, simulation, resonance, acceleration	151
	H.S. Song, J.-S. Chai, H.W. Kim, B.N. Lee, J.H. Oh SKKU, Suwon, Republic of Korea
	The number of PET facility is rapidly increasing worldwide. To get PET image, circular accelerator such as cyclotron is needed. Compact 9 MeV H-cyclotron, which has a diameter of 1.25m is being designed at Sungkyunkwan University starting from July 2010 for getting F-18. It is expected to be constructed by next year. In this paper, RF system of 9 MeV cyclotron including design processes and detail analysis of result is reported. RF system mainly describes RF cavity design.

MOPC040	The Measurement of Transversal Shunt Impedance of RF Deflector	impedance, simulation, dipole, emittance	163
	A.Yu. Smirnov, M.V. Lalayan, N.P. Sobenin MEPhI, Moscow, Russia A.A. Zavadtsev Nano, Moscow, Russia
	This paper presents the results of transverse shunt impedance measurement performed using field perturbation technique and comparison with numerical MWS simulations. The structure under test is the S-band 3-cell deflecting cavity. The mentioned cavity operates with a dipole TM11-like mode with a phase shift of 120 deg per cell. The analyses were carried out with use of two types of perturbing beads: dielectric beads and metallic rings. The latter type perturbs the on-axis magnetic field much stronger than the electric field, which allows us calculating transversal shunt impedance using on-axis EM fields values.

MOPC041	Cross-Field Multipactor Discharge in the X-Band Cylindrical Cavity	multipactoring, electron, vacuum, radiation	166
	S.V. Kuzikov, E.V. Ilyakov, I.S. Kulagin, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia D. Lee NSRRC, Hsinchu, Taiwan
	The paper represents the experimental study of one-sided cross-field multipactor discharge in the copper cavity with the operating mode TM01 in external DC magnetic field. It was shown that discharge is very sensible to magnitudes of the external magnetic field and rf fields as well. At proper fields the multipactor discharge can be developed for 15 ns and the electron concentration can be comparable with critical one for the given rf frequency. As a result of discharging, the cavity changes its own resonant frequency and can play a role of a switch which can substitute full transmission by full reflection. Switching parameters could be controlled by DC magnetic field as well as by additional rf radiation at different frequency than operating frequency. The high rf absorption of multipactor discharge also can be used in electrically controlled powerful loads and attenuators.

MOPC043	Electromagnetic Simulations of the Input Power Couplers for the ESS-Bilbao RFQ	rfq, linac, vacuum, radio-frequency	172
	O. Gonzalez, I. Bustinduy, N. Garmendia, J.L. Munoz, A. Velez ESS Bilbao, Bilbao, Spain F.J. Bermejo Bilbao, Faculty of Science and Technology, Bilbao, Spain V. Etxebarria, J. Portilla University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
	An input power system is currently being designed at ESS-Bilbao in order to inject the RF power provided by a klystron into the RFQ as part of the linac. In this work, some input power couplers based on a coaxial topology are carefully studied from an electromagnetic point of view. As we will show, the electrical properties of the ceramic window used to ensure the vacuum of the RFQ crucially deteriorates the matching of the devices. To overcome this drawback, a full-wave electromagnetic simulator is used to optimize the coupler dimensions in order to minimize both the return and insertion losses.

MOPC045	Commissioning of the ALBA Storage Ring RF System	LLRF, storage-ring, HOM, pick-up	178
	F. Pérez, B. Bravo, A. Salom, P. Sanchez CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	ALBA is a 3 GeV, 400 mA, 3rd generation Synchrotron Light Source that is under commissioning in Cerdanyola, Spain. The RF System has to provide 3.6 MV of accelerating voltage and restore up to 540 kW of power to the electron beam. For that six RF plants, working at 500 MHz, are foreseen. The RF plants include several new developments: DAMPY cavity; the normal conducting HOM damped cavity developed by BESSY and based in the EU design; six are installed. CaCo; a cavity combiner to add the power of two 80 kW IOTs to produce the 160 kW needed for each cavity. WATRAX; a waveguide transition to coaxial, specially designed to feed the DAMPY cavities due to the geometrical and cooling constrains. Digital LLRF; fully designed at ALBA using commercial components. This paper shortly describes these systems and reports their performance during the ALBA commissioning.

MOPC046	CaCo: A Cavity Combiner for IOTs Amplifiers	simulation, storage-ring, high-voltage, HOM	181
	B. Bravo, F. Mares, F. Pérez, P. Sanchez CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain M.L. Langlois ESRF, Grenoble, France
	The ALBA storage ring uses six room temperature cavities; each one fed by two 80 kW IOTs amplifiers at 499.654 MHz. The power of the pair of transmitters is combined by a cavity combiner, CaCo. One of the design requirements of CaCo was that it continued working safely and with a good efficiency in the case of an IOT failure (asymmetrical mode). During the first asymmetric full power tests, in May 2010, with an active IOT and the other passive, the result was dramatic, the passive IOT broke in two parts after few hours of operation. This paper presents the experimental results and the electromagnetic field simulations of the asymmetrical operation mode of CaCo, i.e. one active IOT and the other passive, and analyze why the ceramic of the output tube of the passive IOT broke during the first performance of this mode. Also, it reports a possible solution to solve this problem.

MOPC047	RF Design of the Re-buncher Cavities for the LIPAC Deuteron Accelerator	impedance, vacuum, linac, beam-transport	184
	A. Lara, I. Podadera, F. Toral CIEMAT, Madrid, Spain
	Funding: Work partially supported by Spanish Ministry of Science and Innovation under project ENE2009-11230. Re-buncher cavities are an essential component of LIPAC (Linear IFMIF Prototype Accelerator), presently being built at Rokkasho (Japan). The deuteron beam exiting from the RFQ (Radio Frequency Quadrupole) structure has to be properly adapted to the superconducting RF (SRF) linac. Re-bunchers are placed in the Medium Energy Beam Transport (MEBT) line and their objective is to longitudinally focus the deuteron beam. IFMIF re-bunchers must provide a 350 kV E0LT at 175 MHz continuous wave (CW). The available length for the re-buncher is limited by the general layout of the MEBT. The high power dissipation derived from the high effective voltage and the short available length is an important design challenge. Four different normal conducting cavity designs were investigated: the pillbox type, double gap coaxial resonators, and multi-gap quarter wave and H resonators. The performance of these cavities was studied with the numerical codes HFSS and ANSYS. The fundamental frequency and field pattern of each re-buncher was investigated in HFSS. This work presents the results of such analyses.

MOPC049	Bead-pull Test Bench for Studying Accelerating Structures at RHUL	rfq, quadrupole, controls, resonance	187
	S. Molloy ESS, Lund, Sweden R. Ainsworth, G.E. Boorman Royal Holloway, University of London, Surrey, United Kingdom C. Gabor STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom A. Garbayo AVS, Eibar, Gipuzkoa, Spain A.P. Letchford STFC/RAL, Chilton, Didcot, Oxon, United Kingdom A. Lyapin JAI, Egham, Surrey, United Kingdom P. Savage Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	A bead-pull test stand has been constructed at Royal Holloway, University of London (RHUL) with the ability to provide electric field profile measurements along five degrees of freedom using the perturbation method. In this paper, we present example measurements using the test bench which include a field flatness profile of a 324MHz four vane Radio Frequency Quadrupole (RFQ) model designed as part of the Front End Test Stand (FETS) development at Rutherford Appleton Laboratory (RAL). Mechanical and operational details of the apparatus will also be described, as well as future plans for the development and usage of this facility.

MOPC050	Multipacting Analysis for the Superconducting RF Cavity HOM Couplers in ESS	electron, simulation, HOM, superconducting-RF	190
	S. Molloy ESS, Lund, Sweden R. Ainsworth Royal Holloway, University of London, Surrey, United Kingdom R.J.M.Y. Ruber Uppsala University, Uppsala, Sweden
	The European Spallation Source (ESS) linac will consist of three families superconducting RF cavities to accelerate protons to the required 5 MW for collision with the target. If it is determined that HOM damping is required to limit the effect of beam induced modes, it is quite likely that HOM couplers will be installed. Multipacting in these couplers is a concern as thermally induced detuning of the fundamental notch filter has limited the achievable gradient in other high power machines. It is therefore important to avoid potential multipacting conditions during the design phase. Presented here are simulations using the Track3P code developed at SLAC. Multipacting regions are highlighted, electron trajectories are shown, and suitability of the proposed HOM coupler design is discussed.

MOPC051	The 100 MHz RF System for the MAX IV Storage Rings	LLRF, storage-ring, HOM, impedance	193
	Å. Andersson, E. Elafifi, M. Eriksson, D. Kumbaro, P. Lilja, L. Malmgren, R. Nilsson, H. Svensson, P.F. Tavares MAX-lab, Lund, Sweden J.H. Hottenbacher RI Research Instruments GmbH, Bergisch Gladbach, Germany A. Milan CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain A. Salom ELETTRA, Basovizza, Italy
	The construction of the MAX IV facility has started and user operation is scheduled to commence 2015. The facility is comprised of two storage rings optimized for different wavelength ranges, and a linac-based short pulse facility. In this paper the RF systems for the two storage rings are described. The RF systems will be based on either tetrode or solid state amplifiers working at 100 MHz. Circulators will be used to give isolation between cavity and power amplifier. The main cavities are of normal conducting, entire copper, capacity loaded type, where the present cavities at MAX-lab has served as prototypes. For the MAX IV ring operation it is essential to elongate bunches, in order to minimize the influence of intra beam scattering on beam transverse emittances. For this, 3rd harmonic passive (Landau-) cavities are employed. These are of similar type as the main cavities, mainly because the capacity loaded type has the advantage of pushing higher order modes to relatively high frequencies compared to pill-box cavities. Digital low level RF systems will be used, bearing in mind the possibility of post mortem analysis.

MOPC053	Mechanical Design and Fabrication Studies for SPL Superconducting RF Cavities	niobium, linac, SRF, proton	199
	S. Atieh, G. Arnau-Izquierdo, I. Aviles Santillana, O. Capatina, T. Renaglia, T. Tardy, N. Valverde Alonso, W. Weingarten CERN, Geneva, Switzerland
	CERN’s R&D programme on the Superconducting Proton Linac’s (SPL) superconducting radio frequency (SRF) elliptical cavities made from niobium sheets explores new mechanical design and consequently new fabrication methods, where several opportunities for improved optimization were identified. A stainless steel helium vessel is under design rather than a titanium helium vessel using an integrated brazed transition between Nb and the SS helium vessel. Different design and fabrication aspects were proposed and the results are discussed hereafter.

MOPC055	High Power Test of the First PIMS Cavity for Linac4	linac, pick-up, vacuum, klystron	205
	F. Gerigk, J.-M. Giguet, P. Ugena Tirado, R. Wegner CERN, Geneva, Switzerland
	The PI-Mode Structure (PIMS) accelerates the Linac4 beam from 100 to 160 MeV. Twelve 7-cell cavities will be installed in the linac, with a gradient of ~4 MV/m and operating at a frequency of 352.2 MHz. A full-power prototype has been constructed at CERN in 2010 and was high- power tested in autumn 2010. Peak power tests at the Linac4 duty cycle and high-average power tests at increased duty cycles were completed successful, so that this prototype will be the first of the 12 cavities to be installed in Linac4. This paper reports on the high-power tests and the conditioning experience.

MOPC056	The Linac4 Power Coupler	linac, coupling, vacuum, simulation	208
	F. Gerigk, J.-M. Giguet, E. Montesinos, B. Riffaud, P. Ugena Tirado, R. Wegner CERN, Geneva, Switzerland
	Linac4 employs 3 types of accelerating structures after the RFQ: a Drift Tube Linac (DTL), a Cell-Coupled DTL (CCDTL), and a Pi-Mode Structure (PIMS) to accelerate the beam to 160 MeV. The structures are designed for a peak power of 1 MW per coupler, which consists of two parts: a ceramic window, which separates the cavity vacuum from the air in the wave-guides, and a so-called "coupling T", which couples the RF power through an iris to the cavity. In the frame of the Linac4 R&D both devices have been significantly improved with respect to their commonly used design. On the coupler side, the wave-guide short circuit with its matched length has been replaced by a fixed length λ/4 short circuit. The RF matching is done by a simple piston tuner, which allows a quick matching to different cavity quality factors. In the window part, which usually consists of a ceramic disc and 2 pieces of wave-guides with matching elements, the wave-guide sections could be completely suppressed, so that the window became very compact, lightweight, and much simpler to manufacture. In this paper we present electromagnetic simulations, and tests on first prototypes, which were constructed at CERN.

MOPC058	Upgrade of the 200 MHz RF System in the CERN SPS	emittance, impedance, extraction, acceleration	214
	E.N. Shaposhnikova, E. Ciapala, E. Montesinos CERN, Geneva, Switzerland
	The 200 MHz RF system, used in the SPS to accelerate all beams including those for the LHC, has four travelling wave structure cavities of different length. To stabilize the future higher intensity LHC beams in the SPS a larger (than now) controlled longitudinal emittance blow-up and therefore larger bucket and voltage amplitude will be necessary. However less voltage will be available in the existing system (which has a maximum peak RF power of 1 MW per cavity) due to the increased beam loading, in particular in the long cavities. This issue will be critical for beam acceleration but especially for beam transfer into the 400 MHz RF system of the LHC. The proposed solution is to shorten the two long cavities and use the freed sections together with spare sections to make two extra cavities and install two new power plants of 1.3 MW each. After this upgrade, which is a major part of the more general SPS upgrade for high luminosity LHC to be completed during 2017, the performance of the SPS RF system with high intensity beams will be significantly improved and at the same time the total impedance of the system will be reduced.

MOPC059	The Plane Wave Transformer Linac Development at NSRRC	linac, simulation, impedance, electron	217
	A. Sadeghipanah, J.-Y. Hwang, W.K. Lau NSRRC, Hsinchu, Taiwan T.H. Chang NTHU, Hsinchu, Taiwan
	A Plane-Wave-Transformer (PWT), standing wave linac operating at S-band frequency (2.9979 GHz) is being developed at NSRRC. This structure offers the advantages of high efficiency, compactness, fabrication simplicity and cost. The PWT prototype at NSRRC consists of three cells with two half-cells at the ends, separated by a set of four flat disks suspended and cooled by four water tubes inside a large cylindrical tank. To fully understand its physical properties, numerical modeling of the PWT prototype has been carried out by using the 2-D code SUPERFISH and 3-D code MAFIA. In this paper, we describe the principle properties of this structure, the electric parameters obtained from numerical simulations, and heat dissipation calculation. The mechanical design for prototype linac is also reported.

MOPC061	Simulations to Flatten the Field of the FETS RFQ	rfq, simulation, dipole, quadrupole	223
	S.R. Lawrie, A.P. Letchford STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom J.K. Pozimski, P. Savage Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	A high performance Radio Frequency Quadrupole (RFQ) is the next major component to be installed on the Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL) in the UK. The beam dynamics, RF, thermal and mechanical designs of the RFQ are almost complete and so the copper has recently been purchased with a view to start cutting metal near Summer-time. This report summarizes the simulation work performed to ensure the RF design is sound. This includes performance studies of the end-wall dipole suppression fingers, tuning the frequency of the input and output vane end regions and implementing a simple solution to remove modulation induced field tilt.

MOPC062	EMMA RF Comissioning	LLRF, acceleration, controls, beam-loading	226
	A.J. Moss, R.K. Buckley, P.A. McIntosh, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	EMMA (Electron Model for Many Applications), the world’s first Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) accelerator is presently in operation at Daresbury Laboratory. The LLRF system is required to synchronize with ALICE (Accelerators and Lasers in Combined Experiments) its injector, which operates at 1.3GHz, and to produce an offset frequency of (+1.5 MHz to -4 MHz) to probe the longitudinal beam dynamics and to also maintain the phase and amplitude of the 19 copper RF cavities of the EMMA machine. The design, commissioning and results of the EMMA RF system is presented.

MOPC068	LANSCE RF System Improvements for Current and Future Programs*	klystron, linac, neutron, proton	238
	D. Rees, J.L. Erickson, R.W. Garnett, J.T.M. Lyles, L. Rybarcyk LANL, Los Alamos, New Mexico, USA
	The Los Alamos Neutron Science Center (LANSCE) is in the midst of an upgrade of the RF systems. This project will return LANSCE to its historical operating capability and sustain facility operations into the next decade. The LANSCE accelerator provides pulsed protons and spallation neutrons for defense and civilian applications. This project involves replacing all the existing 201 MHz RF stations and 805 MHz klystrons. LANSCE is also currently in the conceptual design phase of a program called the Material Test Station (MTS) to establish a 1 MW target station to irradiate fast reactor fuels and materials. A pre conceptual design is also in progress to extend the capabilities of MTS to a 2 MW target that will enable the first in a new generation of scientific facilities for the materials community. The emphasis of this new facility is "Matter-Radiation Interactions in Extremes" (MaRIE) which will be used to discover and design the advanced materials needed to meet 21st century national security and energy security challenges. The design and test results of the new RF systems will be presented as well as the RF system changes required to support the new missions.

MOPC072	Design of an RF Feed System for Standing-wave Accelerator Structures	coupling, wakefield, damping, linac	244
	J. Neilson, V.A. Dolgashev, S.G. Tantawi SLAC, Menlo Park, California, USA
	Travelling wave (TW) accelerator structures are known to suffer from several deficiencies. A breakdown in one of the cells propagates towards the source. This results in damage to upstream cells in addition to the cell where the breakdown was initiated. The deficiencies of TW accelerator structures can be overcome by using standing wave (SW) cells that are fed in parallel. An RF breakdown is contained to the cell where it originates. This eliminates upstream cell damage and the resulting changes in phase shift between cells. In addition the feed structure can provide a high conductance port for vacuum pumping. We have completed the design of a parallel fed SW structure with a directional coupler for each cell and serpentine waveguide connection between couplers. This design approach improves isolation between the cells resulting in the maximum increase in the operational robustness of the accelerator structure. The design uses four feed arms spaced uniformly around the cell circumference to suppress dipole modes and improve damping of low order wakefields. Construction of a test structure in now underway and is scheduled for testing in October of this year.

MOPC073	A Dual-mode Accelerating Cavity to Test RF Breakdown Dependence on RF Magnetic Fields	simulation, electron, radio-frequency, vacuum	247
	A.D. Yeremian, V.A. Dolgashev, J. Neilson, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: * Work Supported by Doe Contract No. DE-AC02-76SF00515 RF Breakdown experiments on short accelerating structures at SLAC have shown that increased rf magnetic fields increase the probability of rf breakdowns. Moreover, the breakdown rate is highly correlated with the peak pulse-heating in soft-copper single-cell standing-wave structures of disk-loaded waveguide type. In these geometries the rf electric and magnetic fields are highly correlated. To separate effects of rf magnetic and electric fields on the rf breakdown rate, we have designed an X-band cavity with a geometry as close to that of a standing-wave accelerator cell as practically possible. This cavity supports two modes: an accelerating TM mode and a TE mode with no-surface-electric field but with a strong magnetic field. The cavity will be constructed and tested at the Accelerator Structure Test Area (ASTA) at SLAC.

MOPC077	Commissioning of Multibunch Feedback Systems at the Fast Ramping Stretcher Ring ELSA	kicker, synchrotron, feedback, booster	250
	A. Roth, F. Frommberger, N. Heurich, W. Hillert, M. Schedler, R. Zimmermann ELSA, Bonn, Germany
	Funding: Supported by German Research Foundation through SFB/TR 16 and by Helmholtz Alliance through HA-10¹. At the Electron Stretcher Facility ELSA of Bonn University, an external beam of either unpolarized or polarized electrons is supplied to hadron physics experiments. The ELSA stretcherring operates in the energy range of 1.2 to 3.5 GeV and achieves a duty cycle of up to 80% using a fast energy ramp of 4 GeV/s. Under these conditions, an increase of the internal beam current from an actual value of 20 mA up to 200 mA is planned. Such an upgrade is mainly limited by the excitation of multibunch instabilities. As one active counteraction, we have installed state-of-the-art bunch-by-bunch feedback systems for the longitudinal, as well as for both transverse planes. The detailed setup with all main components and first results of the commissioning of the systems will be presented. In particular, the performance of the longitudinal feedback with a stabilized synchrotron frequency during the fast energy ramp will be discussed.

MOPC078	Operation of Superconducting Cavities in a Fast Ramping Electron Storage Ring	HOM, impedance, acceleration, storage-ring	253
	A. Roth, W. Hillert ELSA, Bonn, Germany
	Funding: Supported by German Research Foundation through SFB/TR 16. The achievable maximum energy of a medium-sized electron accelerator is mainly limited by the accelerating voltage. Using superconducting (sc) cavities, the energy limitation can be shifted considerably. However, the operation of sc multi-cell cavities in a fast ramping storage ring causes additional problems which were investigated at the 3.5 GeV Electron Stretcher Accelerator ELSA. We studied the use of two 500 MHz sc cavities providing the necessary resonator voltage of up to 14 MV and replacing the normal conducting cavities of PETRA type. A large cavity coupling factor is required, so that using the existing 250 kW klystron, an internal beam of 50 mA can be accelerated up to 5 GeV. In addition, a fast detuning of the resonance frequency of the cavities must be implemented during beam injection and the energy ramp of 4 GeV/s. An appropriate 500 MHz structure is given by a five-cell cavity constructed for the JAERI-FEL-LINAC. Based on this geometry, HOM have been calculated from a numerical simulation. Since all monopole and a larger number of dipole HOM are well above the multibunch instabilities threshold, further studies about beam instabilities damping are essential.

MOPC079	Status of the Low Beta 0.07 Cryomodules for SPIRAL2	cryomodule, LLRF, vacuum, linac	256
	P. Bosland, P. Carbonnier, F. Eozénou, P. Galdemard, O. Piquet CEA/DSM/IRFU, France M. Anfreville, C. Madec, L. Maurice CEA/IRFU, Gif-sur-Yvette, France P.-E. Bernaudin, R. Ferdinand GANIL, Caen, France Y. Gomez-Martinez LPSC, Grenoble Cedex, France A. Pérolat CEA, Gif-sur-Yvette, France
	The status of the low beta cryomodules for SPIRAL2, supplied by the Irfu institute of CEA Saclay, is reported in this paper. We summarise in three parts the RF tests performed on the cavities in vertical cryostat, the RF power tests of the qualifying cryomodule performed in 2010 and the RF power tests performed in 2011 on the first cryomodule of the series

MOPC080	First Considerations Concerning an Optimized Cavity Design for the Main Linac of BERLinPro	HOM, linac, coupling, impedance	259
	B. Riemann, T. Weis DELTA, Dortmund, Germany W. Anders, J. Knobloch, A. Neumann HZB, Berlin, Germany H.-W. Glock, C. Potratz, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany F. Marhauser JLAB, Newport News, Virginia, USA
	Funding: work supported by BMBF under contracts 05K10PEA and 05K10HRC The Berlin Energy Recovery Linac Project (BERLinPro) is designed to develop and demonstrate CW linac technology and expertise required to drive next-generation Energy Recovery Linacs. Strongly HOM-damped multicell 1.3 GHz cavities are required for the main linac. The optimization of the cavities presented here is primarily based on the CEBAF 1.5 GHz 5-cell high-current cavity design, including HOM waveguide couplers. The cavity was scaled to 1.3 GHz and extended to 7 cells. Modifications to the end group design have also been studied. An effort was also made to reduce the ratio Epk/Eacc while still permitting HOMs to propagate.

MOPC081	Pulsed Mode Operation and Longitudinal Parameter Measurement of the Rossendorf SRF Gun	gun, SRF, cathode, laser	262
	J. Teichert, A. Arnold, H. Büttig, M. Justus, U. Lehnert, P. Michel, P. Murcek, Ch. Schneider, R. Schurig, R. Xiang HZDR, Dresden, Germany T. Kamps, J. Rudolph, M. Schenk HZB, Berlin, Germany I. Will MBI, Berlin, Germany
	Funding: The European Community-Research Infrastructure Activity under the FP7 program (EuCARD, contract number 227579) the German Federal Ministry of Education and Research grant 05 ES4BR1/8. The Rossendorf SRF gun with a 3 1/2 cell cavity has been operated since 2007. It has produced CW beam with the electron energy of 3 MeV and the average current up to 16 μA. The electron beam of the gun has successfully injected the ELBE superconducting linac since 2010. The Nb cavity has shown constant quality during the operation and for the Cs2Te photocathode life time of months could be obtained. Recently the gun started to run in the pulsed mode with higher gradient. The longitudinal parameters have been measured in this mode. The dark current arose from the high gradient is studied. The main field emission source has been found to be the half cell. Meanwhile, two modified 3+1/2 cell niobium cavities have been fabricated and tested in Jlab. In this paper the new status of the SRF gun will be presented, and the latest results of the beam experiments will be discussed.

MOPC082	Status of the 325 MHz SC CH-Cavity at IAP Frankfurt	simulation, linac, status, electron	265
	M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany M. Amberg, K. Aulenbacher HIM, Mainz, Germany W.A. Barth, S. Mickat GSI, Darmstadt, Germany
	Funding: BMBF contract no. 06FY161I At the Institute for Applied Physics (IAP), University of Frankfurt, a s.c. 325 MHz CH-Cavity is under development for future beam tests at GSI UNILAC, Darmstadt. The cavity with 7 accelerating cells has a geometrical beta of 0.15 corresponding to 11.4 AMeV. The design gradient is 5 MV/m. The geometry of this resonator was optimized with respect to a compact design, low peak fields, surface processing, power coupling and tuning. Furthermore a new tuning system based on bellow tuners inside the resonator will control the frequency during operation. After rf tests in Frankfurt the cavity will be tested with a 10 mA, 11.4 AMeV beam delivered by the GSI UNILAC. In this paper rf simulations, multipacting analysis as well as thermal calculations will be presented.

MOPC083	Structural Mechanics of Superconducting CH Cavities	simulation, controls, linac, resonance	268
	M. Amberg, K. Aulenbacher HIM, Mainz, Germany W.A. Barth, S. Mickat GSI, Darmstadt, Germany M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany
	The superconducting CH-structure (Crossbar-H-mode) is a multi-cell drift tube cavity for the low and medium energy range operated in the H21-mode, which has been developed at the Institute for Applied Physics (IAP) of Frankfurt University. With respect to different high power applications two types of superconducting CH-structures (f = 325 MHz, β = 0.16, seven cells and f = 217 MHz, β = 0.059, 15 cells) are presently under construction and accordingly under development. The structural mechanical simulation is a very important aspect of the cavity design. Furthermore, several simulations with ANSYS Workbench have been performed to predict the deformation of the cavity walls due to the cavity cool-down, pressure effects and mechanical vibrations. To readjust the fast frequency changes in consequence of the cavity shape deformation, a new concept for the dynamic frequency tuning has been investigated, including a novel type of bellow-tuner.

MOPC084	The Superconducting cw LINAC Demonstrator for GSI	linac, solenoid, ion, acceleration	271
	F.D. Dziuba, M. Busch, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany M. Amberg, K. Aulenbacher HIM, Mainz, Germany W.A. Barth, S. Mickat GSI, Darmstadt, Germany
	Funding: BMBF Contr. No. 06FY9089I, Helmholtz Institut Mainz At GSI a new, superconducting (sc) continuous wave (cw) LINAC is under design in cooperation with the Institute for Applied Physics (IAP) of Frankfurt University and the Helmholtz Institut Mainz (HIM). This proposed LINAC is highly requested by a broad community of future users to fulfill the requirements of nuclear chemistry, nuclear physics, and especially in the research field of Super Heavy Elements (SHE). In this context the preliminary layout of the LINAC has been carried out by IAP. The main acceleration of up to 7.3 AMeV will be provided by nine sc Crossbar-H-mode (CH) cavities operated at 217 MHz. Currently, a prototype of the cw LINAC as a demonstrator is under development. The demonstrator comprises a sc CH-cavity embedded between two sc solenoids mounted in a horizontal cryomodule. A full performance test of the demonstrator in 2013/14 by injecting and accelerating a beam from the GSI High Charge Injector (HLI) is one important milestone of the project. The status of the demonstrator is presented.

MOPC085	Quality Assessment for Industrially Produced High-Gradient Superconducting Cavities	niobium, superconducting-cavity, SRF, linac	274
	F. Schlander, S. Aderhold, E. Elsen, D. Reschke, M. Wenskat DESY, Hamburg, Germany
	Funding: This work is supported by the Commission of the European Communities under the 7th Framework Programme “Construction of New Infrastructures – Preparatory Phase”, contract number 206711. A series of some 600 superconducting 1.3 GHz cavities will start being delivered to DESY by industry in early 2012. Although a considerably smaller gradient satisfies the needs for the European XFEL the electro-polished cavities (50% of the delivery) are deemed to be suitable for gradients in excess of 35 MV/m, the performance goal of the International Linear Collider (ILC). Specifically 24 cavities will be supplied without helium tank to enable further investigations. The results may serve to improve overall performance; limitations such as field emission and thermal breakdown of superconductivity ("quench") are still under investigation. For this matter the DESY ILC group has developed tools to monitor aspects of the cavity fabrication. An automated optical mapping system (OBACHT) is being commissioned and will be complemented by software for automated cavity surface feature recognition. For cold RF tests a Second Sound setup for locating the positions of the thermal breakdown is routinely used. These diagnostic tools will give guidance on post-processing cavities for best performance. The current status of these projects will be described.

MOPC086	Description and First Experience with the RF Measurement Procedure for the European XFEL SC Cavity Production	HOM, SRF, cryomodule, superconducting-cavity	277
	A.A. Sulimov, Th. Buettner, A. Gössel, D. Kostin, G. Kreps, W.-D. Möller, D. Reschke, J.H. Thie, K. Twarowski DESY, Hamburg, Germany
	Cavity production for the European XFEL was recently started with first Nb sheets arriving. From this stage to the accelerating module being ready for the linac installation, many critical RF measurements are necessary. During the mechanical cavity fabrication the cavity half-cells, dumb-bells and end-groups are measured and sorted. The cavity spectrum and field profiles are measured and tuned. The HOM (Higher Oder Modes) couplers filter tuning, vertical cavity RF tests, cavity checks during the string assembly and final cavity performance measurements in the module as well as the fundamental mode and HOM RF spectra measurements complete the sequence. We present the procedures of the RF measurements and discuss the first results for the XFEL prototype modules with special attention for the cavity tuning.
	Poster MOPC086 [0.515 MB]

MOPC088	Bead-pull Measurement using Phase-Shift Technique in Multi-cell Elliptical Cavity	linac, vacuum, controls, monitoring	280
	S. Ghosh, A. Mandal, S. Seth, S.S. Som DAE/VECC, Calcutta, India
	The project on the development of high-beta multi-cell elliptical shape superconducting rf linac cavity at around 704 MHz has been funded at VECC, Kolkata, India. A full-scale copper prototype cavity has been designed and fabricated. There are 5 distinct modes exist in the cavity and the accelerating mode is pi-mode in which each cell operates at same frequency with phase difference of 180 degrees between two neighboring cells. A fully automated bead-pull measurement setup has been developed for analyzing these modes and field profile distribution at different modes in such type of linac cavity. A special measurement method inside the cavity using phase-shift technique is proposed in this paper, which describes the development of mechanical setup comprising pulleys and stepper motor–gear arrangement, PC-based control system for precise movement of bead using stepper motor, measurement using VNA, development of software for data acquisition & automation and measurement results for the 5-cell copper prototype cavity.

MOPC089	RF Simulations for the QWR Cavities of PIAVE-ALPI	simulation, ion, linac, beam-losses	283
	M. Comunian, F. Grespan, A. Palmieri INFN/LNL, Legnaro (PD), Italy
	The PIAVE-ALPI linac is composed of several families of QWR cavities. In order to have a thorough description of the accelerator in terms of beam dynamics, a detailed field mapping of the accelerating cavities is necessary, including non-linear behavior of the off-axis fields, as well as the steering and dispersion effects due to transverse components. For such a purpose, a set of RF simulation was accomplished, with the codes HFSS and COMSOL. The details about these simulations and the main outcomes and results will be described in this article.

MOPC090	Tuner Performance in the S1-global Cryomodule	controls, cryomodule, high-voltage, coupling	286
	R. Paparella, A. Bosotti, C. Pagani INFN/LASA, Segrate (MI), Italy C. Albrecht, K. Jensch, L. Lilje DESY, Hamburg, Germany S. Barbanotti, Y.M. Pischalnikov, W. Schappert Fermilab, Batavia, USA H. Hayano, E. Kako, S. Noguchi, N. Ohuchi, Y. Yamamoto KEK, Ibaraki, Japan
	S1-Global is a collaborative effort of INFN, DESY, FNAL, SLAC and KEK, in the framework of the ILC global collaboration. For this project two cryomodules, 6 meter long and hosting four SC cavities each, were realized and successfully cold tested at KEK-STF. Three different cavity tuning systems, provided with fast tuning capability through piezoelectric actuators (piezo), were installed, and fully characterized in static and dynamic operation: Blade Tuner from INFN/FNAL, Saclay Tuner from DESY, Slide Jack Tuner from KEK. Finally, Lorenz Force Detuning (LFD) active compensation has been successfully achieved during high power cavity tests in pulsed RF regime, where active control of the LFD disturbance up to Hz-level residual detuning has been achieved with each type of tuning system up to the maximum gradient of each cavity. The installation procedures, together with the relevant results and their analyses are summarized in the paper.

MOPC091	Status of the XFEL 3.9 GHz Injector Section	cryogenics, cryomodule, linac, status	289
	P. Pierini, M. Bonezzi, A. Bosotti, M. Fusetti, P.M. Michelato, L. Monaco, R. Paparella, D. Sertore INFN/LASA, Segrate (MI), Italy E. Vogel DESY, Hamburg, Germany
	The European XFEL will use a superconducting third harmonic section to achieve the necessary beam quality for the FEL process. The concept has been successfully proven at the FLASH linac in DESY, with a 4 cavity superconducting module contributed by FNAL. The design of the third harmonic system at the XFEL injector is being finalized and prototypes of the components (cavities and couplers) have been fabricated and are currently in the testing stage. The paper will provide a status of the activities.

MOPC092	Effect of Current Densities on Sulfur Generation at Electropolished Niobium Surface	niobium, cathode, electron, vacuum	292
	P.V. Tyagi Sokendai, Ibaraki, Japan H. Hayano, S. Kato, M. Nishiwaki, T. Noguchi, T. Saeki, M. Sawabe KEK, Ibaraki, Japan
	We conducted a series of electropolishing (EP) experiments in aged EP acid with high (≈50 mA/cm²) and low (≈30 mA/cm²) current densities on Nb surfaces. The experiments were carried out both for laboratory coupons and a real Nb single cell cavity with six witness samples located at three typical positions (equator, iris and beam pipe). All the samples surface were investigated by XPS (x-ray photoelectron spectroscopy), SEM (scanning electron microscope) and EDX (energy dispersive x-ray spectroscopy). The surface analysis showed the EP with a high current density produced a huge amount sulfate particles at Nb surface whereas the EP with a low current density is very helpful to mitigate sulfate at Nb surface in both the experiments.

MOPC093	Novel Field Emission Scanner for Surface Study of Niobium SRF Cavity	SRF, electron, site, controls	295
	S. Kato, M. Nishiwaki, T. Noguchi KEK, Ibaraki, Japan V. Chouhan GUAS, Kanagawa, Japan P.V. Tyagi Sokendai, Ibaraki, Japan
	It is mandatory to investigate field emission on Nb SRF cavity systematically since strong field emission often limits the cavity performance. The field emission strength and the number of emission sites strongly depend on Nb surface properties which are determined by its surface treatment and handling. Field emission scanner (FES) developed allows us to measure a distribution of the field emitting sites over a sample surface at a given field strength along with its FE-SEM observation and energy dispersive x-ray analysis. FES consists of an anode needle driven by precise 3D stepping motors and an eucentric sample stage. The compact scanner was installed into the space between the object lens and the SEM sample holder. In addition, this system was newly equipped with a sample load-lock system for existing UHV suitcases. Therefore a sample coupon to be observed is hardly exposed to contaminants and dust particles during the transportation. In-situ heating of a sample coupon can be done during an experiment to simulate a baking process of a SRF cavity. This article describes development of the field emission scanner and its preliminary results of the application to niobium samples.

MOPC095	Superconducting Cavity R&D for ILC at MHI	HOM, superconducting-cavity, linac, status	298
	H. Hitomi, H. Hara, F. Inoue, K. Kanaoka, K. Sennyu, T. Yanagisawa MHI, Kobe, Japan
	We have developed and manufactured some superconducting RF cavity for STF project in KEK. In recent vertical test in KEK, the MHI-#12 cavity which is one of cavities for STF phase 2 project reached ILC specification(max Eacc was about 40MV/m). So techniques for manufacturing cavity is making steady progress in MHI. To be realized ILC project, we also try to decrease the manufacturing cost by using some new techniques, for example Laser Beam Welding, deep drawing, seamless dumbbell, etc. In this meeting, we will report recent MHI's activities for ILC.

MOPC096	Design and Fabrication of a 5-Cell High Current Superconducting Cavity	HOM, simulation, dipole, quadrupole	301
	Y.M. Li, K.X. Liu, S.W. Quan, F. Zhu PKU/IHIP, Beijing, People's Republic of China R. Nassiri ANL, Argonne, USA
	Funding: National High Technology Research and Development program 863 (2009AA03Z206) Energy recovery linacs (ERL) is promising to achieve high average current with superior beam quality. The key component for accelerating such high current beams is the superconducting radio frequency (SRF) cavity. The design of a 1.3 GHz 5-cell high current superconducting cavity has been carried out under the cooperation between Peking University (PKU) and Argonne National Laboratory (ANL). RF properties, damping of the HOMs, multipacting and mechanical features of this cavity have been discussed and the final design is presented.

MOPC097	LLRF Control System for PKU DC-SC Photocathode Injector	controls, LLRF, superconducting-cavity, SRF	304
	H. Zhang, Y.M. Li, K.X. Liu, F. Wang, B.C. Zhang PKU/IHIP, Beijing, People's Republic of China
	A 1.3 GHz 3.5 Cell LG niobium cavity is installed for the new PKU DC-SC injector as its accelerating cavity with working temperature is 2K. High amplitude and phase stability is required for the updated SRF photocathode injector. This paper describes the design of Low Level RF control system based on FPGA, including hardware and software,and the communication function is realized by Tri-State Ethernet. The system should be operated on the precision with the amplitude of ±0.1% and phase stability of ±0.1°.

MOPC101	Vertical Test of PEFP Prototype SRF Cavity	accelerating-gradient, electron, linac, SRF	307
	H.S. Kim, Y.-S. Cho, H.-J. Kwon KAERI, Daejon, Republic of Korea
	Funding: This work was supported by Ministry of Education, Science and Technology of the Korean Government. The PEFP Proton linac is a 100-MeV machine which consists of a proton injector, a 3-MeVRFQ and 100-MeV DTL. For the extension of the machine beyond 100 MeV, SRF technology is under consideration. As a prototyping activity, a superconducting RF cavity with a geometrical beta of 0.42 and a resonant frequency of 700 MHz has been designed, fabricated and tested. The cavity is an elliptical shape with 5 cells stiffened by double-ring structure. A design accelerating gradient is 8.0 MV/m at the operating temperature of 4.2 K and maximum duty factor is 9%. For the vertical test of the cavity, a cryostat with a vacuum jacket and multi-layer insulation was prepared. The RF system for driving the cavity is based on PLL to track the resonant frequency. In case of lack of RF power, a two-way RF power combiner based on splitted coaxial transmission line is considered. The details of the vertical test setup and test results will be presented in this paper.

MOPC102	RF and Surface Properties of Superconducting Samples	niobium, quadrupole, superconductivity, superconducting-cavity	310
	T. Junginger, W. Weingarten CERN, Geneva, Switzerland T. Junginger MPI-K, Heidelberg, Germany R. Seviour Lancaster University, Lancaster, United Kingdom C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: Work supported by the German Doctoral Students program of the Federal Ministry of Education and Research (BMBF) The surface resistance Rs of superconducting cavities can be obtained from the unloaded quality factor Q0. Since Rs varies strongly over the cavity surface its value must be interpreted as averaged over the whole cavity surface. A more convenient way to investigate the surface resistance of superconducting materials is therefore to examine small samples, because they can be manufactured cheaply, duplicated easily and used for further surface analyses. At CERN a compact Quadrupole Resonator has been developed for the RF characterization of superconducting samples at different frequencies. In this contribution, results from measurements on bulk niobium and niobium film on copper samples are presented. It is shown how different contributions to the surface resistance depend on temperature, applied RF magnetic field and frequency. Furthermore, measurements of the maximum RF magnetic field as a function of temperature and frequency in pulsed and CW operation are presented. The study is accompanied by measurements of the surface properties of the samples by various techniques.

MOPC103	Cryostat for Testing HIE-ISOLDE Superconducting RF Cavities	vacuum, cryomodule, cryogenics, niobium	313
	O. Capatina, J.P. Brachet, G. Cuccuru, M. Pasini, T. Renaglia, M. Therasse, B. Vullierme CERN, Geneva, Switzerland
	The High Intensity and Energy ISOLDE (HIE-ISOLDE) project is a major upgrade of the existing ISOLDE and REX-ISOLDE facilities at CERN [1], with the objective of increasing the energy and the intensity of the delivered radioactive ion beams (RIB). This project aims to fill the request for a more energetic post accelerated beam by means of a new superconducting (SC) linac based on Quarter Wave Resonators (QWRs). A research and development program looking at all different aspects of the SC linac has started in 2008 and continued throughout 2010. In particular the R&D effort has focused on the development of the high β cavity (β = 10.3%), for which it has been decided to adopt the Nb sputtered on Cu substrate technology. Two prototype cavities were manufactured and are undergoing RF cold tests. The pre-series cavity fabrication is under way using 3D forged Cu billets. A single vacuum cryostat was designed and built to test these cavities at liquid helium temperatures. The paper details the main design concepts of the test cryostat as well as the results of the cryogenic behavior of the complete set-up including the cryostat, the RF cavity, the tuner and the main coupler.

MOPC104	HIE-ISOLDE SRF Development Activities at CERN	cathode, vacuum, niobium, SRF	316
	M. Therasse, O. Brunner, S. Calatroni, J.K. Chambrillon, B. Delaup, M. Pasini CERN, Geneva, Switzerland
	The HIE-ISOLDE project has initiated a new development phase on the SRF domain at CERN. In particular, the HIE-ISOLDE project aims at the construction of the 32 Quarter Wave Resonators (QWRs) using the Nb on Cu sputtering technology. The paper describes the refurbishment of the test infrastructure and the activities from the cavity production to the cold test, including quality assurance procedure for the correct handling of the resonators.

MOPC105	Design of the High Beta Cryomodule for the HIE-ISOLDE Upgrade at CERN	vacuum, alignment, cryomodule, target	319
	L.R. Williams, A.P. Bouzoud, N. Delruelle, J. Gayde, Y. Leclercq, M. Pasini, J.Ph. G. L. Tock, G. Vandoni CERN, Geneva, Switzerland
	The major upgrade of the energy and intensity of the radioactive ion beams of the existing ISOLDE and REX-ISOLDE facilities at CERN will, in the long term, require downstream of the existing machine, the installation of four high-β and two low-β cryo-modules. The first stage of this upgrade, involving the design, construction, installation and commissioning of two high-β cryo-modules is approved and design work is underway at CERN. The high-β cryo-module houses five high-β superconducting cavities and one superconducting solenoid. As well as providing optimum conditions for physics, where the internal active components must remain aligned within tight tolerances, the cryo-modules need to function under stringent common vacuum and cryogenic conditions. To preserve the RF cavity performance their assembly and sub-system testing will need to be carried out using specifically designed tooling in a class 100 clean-room. We present the determining factors constraining the design of the high-β cryo-module together with the design choices that these factors have imposed.

MOPC106	Study of the Variation of Transverse Voltage in the 4 Rod Crab Cavity for LHC	luminosity, simulation, HOM, dipole	322
	B.D.S. Hall, P.K. Ambattu, G. Burt, C. Lingwood Cockcroft Institute, Lancaster University, Lancaster, United Kingdom P. Goudket, C. Hill STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The planned high luminosity upgrade to LHC will utilise crab cavities to rotate the beam in order to increase the luminosity in the presence of a finite crossing angle. A compact design is required in order for the cavities to fit between opposing beam-lines. In this paper we discuss we discuss one option for the LHC crab cavity based on a 4 rod TEM deflecting cavity. Due to the large transverse size of the LHC beam the cavity is required to have a large aperture while maintaining a constant transverse voltage across the aperture. The cavity has been optimised to minimise the variation of the transverse voltage while keeping the peak surface electric and magnetic fields low for a given kick. This is achieved while fitting within the strict design space of the LHC. The variation of deflecting voltage across the aperture has been studied numerically and compared with numerical and analytical estimates of other deflecting cavity types. Performance measurements an aluminium prototype of this cavity are presented and compared to the simulated design.

MOPC107	HOM and FP Coupler Design for the NLSF High Gradient SC Cavity	HOM, simulation, SRF, damping	325
	R.M. Jones, N. Juntong UMAN, Manchester, United Kingdom
	The design of both higher order mode (HOM) and fundamental power (FP) couplers for the New Low Surface Field (NLSF) cavity* is presented. Here we study using the ILC baseline couplers for this new superconducting cavity. A Balleyguier method** of calculating external quality factor is used and the results validated using both Microwave studio and HFSS. * N. Juntong and R.M. Jones, SRF2009, THPPO024, 2009. ** P. Balleyguier, LINAC98, MO4037, 1998

MOPC108	Cornell SRF New Materials Program*	niobium, SRF, controls, monitoring	328
	S. Posen, M. Liepe, Y. Xie CLASSE, Ithaca, New York, USA
	Funding: Work supported by NSF Career award PHY-0841213, DOE award ER41628, and the Alfred P. Sloan Foundation The SRF group at Cornell has recently pioneered an extensive program to investigate alternative materials for superconducting cavities. We have developed facilities to fabricate Nb3Sn, a superconductor which will theoretically be able to reach more than twice the maximum accelerating field of Nb in a cavity under the same operating conditions. In addition, with the critical temperature of Nb3Sn being twice that of Nb, Nb3Sn would allow operation of SRF cavities with a much higher cryogenic efficiency. We have also manufactured two TE cavities that measure the RF properties of small, flat samples, ideal for material fabrication methods in development. This paper presents an overview of the materials research program. First results from tests of Nb3Sn samples are presented.

MOPC109	Suppression of Coupler Kicks in 7-Cell Main Linac Cavities for Cornell's ERL	linac, emittance, resonance, simulation	331
	N.R.A. Valles, M. Liepe, V.D. Shemelin CLASSE, Ithaca, New York, USA
	Funding: Supported by NSF award DMR-0807731 Cornell is developing a 5 GeV Energy Recovery Linac operating at 100 mA with very small emittances (~30 pm at 77 pC bunch charge) in the horizontal and vertical directions. We investigate the effect of the fundamental RF power couplers of the main linac SRF cavities on the beam using the ACE3P software package. The cavities in the ERL main linac will be operated at very high loaded quality factors of up to 6.5·10⁷, corresponding to a full bandwidth of only 20 Hz. Cavity microphonics will detune the cavities by more than one bandwidth during operation, thereby causing a time dependent change of the coupler kick in addition to its fast oscillation at the RF frequency. In order to investigate the dependence of the coupler kick on the cavity frequency, we calculate the coupler kick given to the beam for the case of a detuned RF cavity. We show that a compensation stub geometry located opposite to the input coupler port can be optimized to reduce the overall kick given to the beam and the emittace growth caused by its time dependence.

MOPC111	Progress of ILC High Gradient SRF Cavity R&D at Jefferson Lab	SRF, niobium, accelerating-gradient, cryogenics	334
	R.L. Geng, J. Dai, G.V. Eremeev, A.D. Palczewski JLAB, Newport News, Virginia, USA
	Funding: US Department of Energy Latest progress of ILC high gradient SRF cavity R&D at Jefferson Lab will be presented. 9 out of 10 real 9-cell cavities reached an accelerating gradient of more than 38 MV/m at a unloaded quality factor of more than 8·10⁹. New understandings of quench limitation in 9-cell cavities are obtained through instrumented studies of cavities at cryogenic temperatures. Our data have shown that present limit reached in 9-cell cavities is predominantly due to localized defects, suggesting that the fundamental material limit of niobium is not yet reached in 9-cell cavities and further gradient improvement is still possible. Some examples of quench-causing defects will be given. Possible solutions to pushing toward the fundamental limit will be described.

MOPC112	Fabrication and Testing Status of CEBAF 12 GeV Upgrade Cavities	cryomodule, HOM, electron, status	337
	F. Marhauser, A. Burrill, G.K. Davis, D. Forehand, C. Grenoble, J. Hogan, R.B. Overton, A.V. Reilly, R.A. Rimmer, M. Stirbet JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The 12 GeV upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory (JLab) is under way. All cavities have been built by industry and are presently undergoing post-processing and final low and high power qualification before cryomodule assembly. The status is reported including fabrication-related experiences, observations and issues throughout production, post-processing and qualification.

MOPC113	Results of Cavity Series Fabrication at Jefferson Laboratory for the Cryomodule “R100”	cryomodule, HOM, target, damping	340
	F. Marhauser, W.A. Clemens, M.A. Drury, D. Forehand, J. Henry, S. Manning, R.B. Overton, R.S. Williams JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. A series production of eight superconducting RF cavities for the cryomodule R100 was conducted at JLab in 2010. The cavities underwent chemical post-processing prior to vertical high power testing and routinely exceeded the envisaged performance specifications. After cryomodule assembly, cavities were successfully high power acceptance tested. In this paper, we present the achievements paving the way for the first demonstration of 100 MV (and beyond) in a single cryomodule to be operated at CEBAF.

MOPC114	Design, Fabrication and Testing of Medium-Beta 650 MHz SRF Cavity Prototypes for Project-X	SRF, linac, electron, vacuum	343
	F. Marhauser, W.A. Clemens, J. Henry, P. Kneisel, R. Martin, R.A. Rimmer, G. Slack, L. Turlington, R.S. Williams JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. A new type of superconducting radio frequency (SRF) cavity shape with a shallow equator dome to reduce electron impact energies for suppressing multipacting barriers has been proposed. The shape is in consideration for the first time in the framework of Project-X to design a potential multi-cell cavity candidate for the medium-beta section of the SRF proton CW linac operating at 650 MHz. Rationales covering the design of the multi-cell cavity, the manufacture, post-processing and high power testing of two single-cell prototypes are presented.

MOPC115	JLab SRF Cavity Fabrication Errors, Consequences and Lessons Learned	cryomodule, target, SRF, niobium	346
	F. Marhauser JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 Today, elliptical superconducting RF (SRF) cavities are preferably made from deep-drawn niobium sheets as pursued at Jefferson Laboratory (JLab). The fabrication of a cavity incorporates various cavity cell machining, trimming and electron beam welding (EBW) steps as well as surface chemistry that add to forming errors creating geometrical deviations of the cavity shape from its design. An analysis of in-house built cavities over the last years revealed significant errors in cavity production. Past fabrication flaws are described and lessons learned applied successfully to the most recent in-house series production of multi-cell cavities.

MOPC116	Development of Nb and Alternative Material Thin Films Tailored for SRF Applications	SRF, ECR, ion, electron	349
	A-M. Valente-Feliciano, H.L. Phillips, C.E. Reece, J.K. Spradlin, B. Xiao, X. Zhao JLAB, Newport News, Virginia, USA H. Baumgart, D. Gu ODU, Norfolk, Virginia, USA D. Beringer, R.A. Lukaszew The College of William and Mary, Williamsburg, USA K.I. Seo NSU, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S.DOE Contract No. DE-AC05-06OR23177. Over the years, Nb/Cu technology, despite its shortcomings due to the commonly used magnetron sputtering, has positioned itself as an alternative route for the future of superconducting structures used in accelerators. Recently, significant progress has been made in the development of energetic vacuum deposition techniques, showing promise for the production of thin films tailored for SRF applications. JLab is pursuing energetic condensation deposition via techniques such as Electron Cyclotron Resonance and High Power Impulse Magnetron Sputtering. As part of this project, the influence of the deposition energy on the material and RF properties of the Nb thin film is investigated with the characterization of their surface, structure, superconducting properties and RF response. It has been shown that the film RRR can be tuned from single digits to values greater than 400. This paper presents results on surface impedance measurements correlated with surface and material characterization for Nb films produced on various substrates, monocrystalline and polycrystalline as well as amorphous. A progress report on work on NbTiN and AlN based multilayer structures will also be presented.

MOPC117	Advance in Vertical Buffered Electropolishing on Niobium for Particle Accelerators*	SRF, cathode, niobium, radio-frequency	352
	A.T. Wu, S. Jin, J.D. Mammosser, C.E. Reece, R.A. Rimmer JLAB, Newport News, Virginia, USA L. Lin, X.Y. Lu, K. Zhao PKU/IHIP, Beijing, People's Republic of China
	Funding: The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes. Niobium (Nb) is the most popular material that has been employed for making superconducting radio frequency (SRF) cavities to be used in various particle accelerators over the last couple of decades. One of the most important steps in fabricating Nb SRF cavities is the final chemical removal of 150 μm of Nb from the inner surfaces of the SRF cavities. This is usually done by either buffered chemical polishing (BCP) or electropolishing (EP). Recently a new Nb surface treatment technique called buffered electropolishing (BEP) has been developed at Jefferson Lab. It has been demonstrated that BEP can produce the smoothest surface finish on Nb ever reported in the literature while realizing a Nb removal rate as high as 10 μm/min that is more than 25 and 5 times quicker than those of EP and BCP(112) respectively. In this contribution, recent advance in optimizing and understanding BEP treatment technique is reviewed. Latest results from RF measurements on BEP treated Nb single cell cavities by our unique vertical polishing system will be reported. Authored by The Southeastern Universities Research Association, Inc. under U.S. DOE Contract No. DE-AC05-84ER40150.

MOPC118	Effects of the Thickness of Niobium Surface Oxide Layers on Field Emission*	controls, SRF, niobium, HOM	355
	A.T. Wu, S. Jin, J.D. Mammosser, R.A. Rimmer JLAB, Newport News, Virginia, USA X.Y. Lu, K. Zhao PKU/IHIP, Beijing, People's Republic of China
	Funding: The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes. Field emission on the inner surfaces of niobium superconducting radio frequency cavities is still one of the major obstacles for reaching high accelerating gradients for SRF community. Our previous experimental results* seemed to imply that the threshold of field emission was related to the thickness of Nb surface oxide layers. In this contribution, a more detailed study on the influences of the surface oxide layers on the field emission on Nb surfaces will be reported. By anodization technique, the thickness of the surface pentoxide layer was artificially fabricated from 3 nm up to 460 nm. A home-made scanning field emission microscope was employed to perform the scans on the surfaces. Emitters were characterized using a scanning electron microscope together with an energy dispersive x-ray analyzer. The SFEM experimental results were analyzed in terms of surface morphology and oxide thickness of Nb samples and chemical composition and geographic shape of the emitters. A model based on the classic electromagnetic theory was developed trying to understand the experimental results. Possibly implications for Nb SRF cavity applications from this study will be discussed. * A.T. Wu et al., Proc. of IPAC 2010, Kyoto, Japan, WEPEC081, p. 3067 (2010). Authored by The Southeastern Universities Research Association, Inc. under U.S. DOE Contract No. DE-AC05-84ER40150.

MOPC119	Fastest Electropolishing Technique on Niobium for Particle Accelerators*	SRF, cathode, niobium, linear-collider	358
	A.T. Wu, S. Jin, R.A. Rimmer JLAB, Newport News, Virginia, USA X.Y. Lu, K. Zhao PKU/IHIP, Beijing, People's Republic of China
	Funding: The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes. Field emission on the inner surfaces of niobium (Nb) superconducting radio frequency (SRF) cavities is still one of the major obstacles for reaching high accelerating gradients for SRF community. Our previous experimental results [1] seemed to imply that the threshold of field emission was related to the thickness of Nb surface oxide layers. In this contribution, a more detailed study on the influences of the surface oxide layers on the field emission on Nb surfaces will be reported. By anodization technique, the thickness of the surface pentoxide layer was artificially fabricated from 3nm up to 460nm. A home-made scanning field emission microscope (SFEM) was employed to perform the scans on the surfaces. Emitters were characterized using a scanning electron microscope together with an energy dispersive x-ray analyzer. The experimental results could be understood by a simple model calculation based on classic electromagnetic theory as shown in Ref.1. Possibly implications for Nb SRF cavity applications from this study will be discussed. Authored by The Southeastern Universities Research Association, Inc. under U.S. DOE Contract No. DE-AC05-84ER40150.

MOPC120	Design of Superconducting Parallel-bar Deflecting/Crabbing Cavities	coupling, luminosity, SRF, proton	361
	J.R. Delayen, S.U. De Silva ODU, Norfolk, Virginia, USA
	The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. We present an analysis of several designs of parallel-bar cavities and their electromagnetic properties.

MOPC121	Design of Low-frequency Superconducting Spoke Cavities for High-velocity Applications	impedance, HOM, superconductivity, linac	364
	J.R. Delayen, C.S. Hopper ODU, Norfolk, Virginia, USA R.G. Olave Old Dominion University, Norfolk, Virginia, USA
	Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β~0.15 to β~0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of 325 and 352 MHz spoke cavities optimized for β=0.8 and β=1.

MOPC122	Etching of Niobium Sample Placed on Superconducting Radio Frequency Cavity Surface in Ar/CL2 Plasma	plasma, SRF, niobium, diagnostics	367
	J. Upadhyay, M. Nikolić, S. Popović, L. Vušković ODU, Norfolk, Virginia, USA H.L. Phillips, A-M. Valente-Feliciano JLAB, Newport News, Virginia, USA
	Plasma based surface modification is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. It has been proven with flat samples that the bulk Niobium (Nb) removal rate and the surface roughness after the plasma etchings are equal to or better than wet etching processes. To optimize the plasma parameters, we are using a single cell cavity with 20 sample holders symmetrically distributed over the cell. These holders serve the purpose of diagnostic ports for the measurement of the plasma parameters and for the holding of the Nb sample to be etched. The plasma properties at RF (100 MHz) and MW (2.45 GHz) frequencies are being measured with the help of electrical and optical probes at different pressures and RF power levels inside of this cavity. The niobium coupons placed on several holders around the cell are being etched simultaneously. The etching results will be presented at this conference.

MOPC123	Temperature Dependent Microphonics in the BNL Electron Cooler*	resonance, electron, linac, cryogenics	370
	P. Jain Stony Brook University, Stony Brook, USA I. Ben-Zvi, C. Schultheiss BNL, Upton, Long Island, New York, USA
	An R&D Energy Recovery Linac (ERL), to be used in the BNL electron cooler, has been operational in a developmental setting. The ERL requires a cryogenic system to supply cooling to a superconducting RF gun and the 5-cell superconducting RF cavity system that is kept cold at 2K. The 2K superfluid bath is produced by pumping on the bath using a sub-atmospheric warm compression system. During a test run in October 2010, a resonance peak corresponding to a noise of 30 Hz was observed at 1.88K. This noise peak, present at all temperatures below 2K, is assumed to be of mechanical origin from the vibration of the cryopump. Another resonance noise peak of 16 Hz, characteristic of the system, was observed at 1.98K, which shifted towards the 30 Hz peak as the temperature of the cryostat varied from 1.98K to 1.88K. The 16 Hz resonance peak upon hitting the 30 Hz resonance peak, sets a resonance condition, thereby the 30 Hz peak getting amplified by more than five times. In this paper we explore the origin of the temperature dependent 16 Hz resonance peak and give a physical explanation of the resonance.

MOPC126	High Power RF System for TRIUMF E-Linac Injector	klystron, TRIUMF, linac, cryomodule	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	storage-ring, power-supply, booster, klystron	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	klystron, linac, rf-amplifier, superconducting-cavity	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	linac, impedance, vacuum, klystron	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)	booster, rf-amplifier, storage-ring, simulation	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.

MOPC134	Multifrequency High Power Microwave Electric-vacuum Devices	electron, klystron, vacuum, acceleration	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	controls, power-supply, linac, LLRF	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	klystron, linac, neutron, LLRF	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	controls, linac, rf-amplifier, shielding	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	klystron, linac, controls, electron	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	controls, resonance, shielding, SRF	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.

MOPC143	A Reduced Gradient Output Design for SLAC's XL4 X-Band Klystron	simulation, klystron, impedance, beam-loading	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.

MOPC145	Recent Progress on the Technical Realization of the Bunch Phase Timing System BuTiS	controls, laser, diagnostics, status	418
	B. Zipfel, P. Moritz GSI, Darmstadt, Germany
	A high precision phase synchronous clock distribution system is mandatory for generating local RF reference signals in an accelerator complex. The dedicated Bunch Timing System (BuTiS) at GSI performs this function. The accuracy of the realized installation under rough ambient conditions is presented. Procedures for calibration and standardization aspects of system modules are pointed out. Hardware as well as software interfaces of the system are described. The interfacing between GPS and BuTiS are explained.

MOPC151	Design and Commissioning of a Multi-frequency Digital Low Level RF Control System*	controls, low-level-rf, linac, superconducting-cavity	433
	M. Konrad, U. Bonnes, C. Burandt, J. Conrad, R. Eichhorn, J. Enders, P.N. Nonn, N. Pietralla TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by DFG through CRC 634 and by the BMBF under 06 DA 9024 I. Triggered by the need to control the superconducting cavities of the S-DALINAC, which have a high loaded quality factor and are thus very susceptible to microphonics, the development of a digital low level RF control system was started. The chosen design proved to be very flexible since other frequencies than the original 3 GHz may be adapted easily: The system converts the RF signal coming from the cavity (e. g. 3 GHz) down to the base band using a hardware I/Q demodulator. The base band signals are digitized by ADCs and fed into a FPGA where the control algorithm is implemented. The resulting signals are I/Q modulated before they are sent back to the cavity. The superconducting cavities are operated with a self-excited loop algorithm whereas a generator-driven algorithm is used for the low Q normal-conducting bunching cavities. A 6 GHz RF front end allows the synchronous operation of a new 2f buncher at the S-DALINAC. Meanwhile, a 325 MHz version has been built to control a pulsed prototype test stand for the p-LINAC at FAIR. We will present the architecture of the RF control system as well as results obtained during operation.

MOPC152	Digital Control System for Solid State Direct Drive™ RF-Linacs	controls, LLRF, linac, pick-up	436
	J. Sirtl, M. Back, T. Kluge Siemens AG, Erlangen, Germany H. Schröder ASTRUM IT GmbH, Erlangen, Germany
	The Solid State Direct Drive™ concept for RF linacs has previously been introduced. Due to the different methodology (i.e. solid state based rather than electron tube based) as compared with conventional RF sources a new control system is required to deliver the required LLRF. To support this new technology a fully digital control system for this new concept has been developed. Progresses in Digital – Analogue Converter technology and FPGA technology allows us to create a digital System which works in the 150 Mhz baseband. The complete functionality was implemented in a Virtex 6 FPGA. Dispensing with the PLL allows an excellent jitter-behaviour. For this job, we use three 12 bit ADCs with a Sampling Rate of 1 GS/s and two 16 bit DACs (1 GS/s). The amplitude of the RF source is controlled by dividing the RF modules mounted on the power combiner* into two groups and controlling the relative phase of each group (in effect mimicking an “out-phasing” amplifier). This allows the modules to be operated at their optimum working point and allows a linear amplitude behaviour. * O. Heid, T. Hughes, Proc. of IPAC10, THPD002, p. 4278, Kyoto, Japan (2010). ** O. Heid, T. Hughes, Proc. of LINAC10, THPD068, Tsukuba, Japan.

MOPC153	Design and Implementation of Automatic Cavity Resonance Frequency Measurement and Tuning Procedure for FLASH and European XFEL Cryogenic Modules	controls, klystron, LLRF, resonance	439
	V. Ayvazyan, W. Koprek, D. Kostin, G. Kreps DESY, Hamburg, Germany Z. Geng SLAC, Menlo Park, California, USA
	The superconducting cavities in FLASH and European XFEL should be tuned to the frequency of 1.3 GHz after cool down and adjusted to initial frequency before warm up by stepper motor tuners. The initial frequency is 300 kHz far from the operating frequency (1.3 GHz) to remove mechanical hysteresis of the tuner. The cavities should be relaxed to initial frequency to avoid a plastically deformation. In framework of digital low level RF and DOOCS control systems we have developed a simple automatic procedure for the remote resonance frequency measurement and simultaneous remote tuning for all cavities which are driven from the single klystron. The basic idea is based on frequency sweeping both for driving klystron and for generation of local oscillator frequency with constant RF frequency from master oscillator. The developed system has been used during FLASH commissioning in spring 2010 and is in use for cavity and cryogenic module test stands for European XFEL at DESY.

MOPC154	RF Photo Gun Stability Measurement at PITZ	gun, laser, feedback, electron	442
	I.I. Isaev, H.-J. Grabosch, M. Gross, L. Hakobyan, Ye. Ivanisenko, G. Klemz, W. Köhler, M. Krasilnikov, M. Mahgoub, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, S. Rimjaem, F. Stephan, G. Vashchenko, S. Weidinger, R.W. Wenndorff DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria M. Hoffmann, H. Schlarb DESY, Hamburg, Germany M.A. Khojoyan YerPhI, Yerevan, Armenia D. Richter HZB, Berlin, Germany A. Shapovalov NRNU MEPHI, Moscow, Russia I.H. Templin, I. Will MBI, Berlin, Germany
	The stability of the RF phase in the RF photo injector gun is one of the most important factors for the successful operation of linac based free-electron lasers. Instabilities in the RF launch phase can significantly reduce the beam quality. Investigation on the dependence of different gun parameters and selection of optimal conditions are required to achieve high RF gun phase stability. The phase stability of the RF field is measured using the phase scan technique. Measurements were performed for different operating conditions at the Photo Injector Test facility at DESY, location Zeuthen (PITZ). Obtained stability measurement results will be presented and discussed.

MOPC155	Performance of the Micro-TCA Digital Feedback Board for DRFS Test at KEK-STF	controls, feedback, klystron, LLRF	445
	T. Miura, D.A. Arakawa, S. Fukuda, E. Kako, H. Katagiri, T. Matsumoto, S. Michizono, Y. Yano KEK, Ibaraki, Japan
	The test of distributed RF scheme (DRFS) for ILC was carried out at the superconducting RF test facility in KEK (KEK-STF). The LLRF system and two klystron units were installed in the same tunnel as SRF cavities. The vector-sum control for two cavities was done by using the micro-TCA digital feedback board. This board was the same one developed for the compact-ERL at KEK, but the software was changed for pulse operation. The result of the performance will be reported.

MOPC156	Operation Test of Distributed RF System with Circulator-less Waveguide Distribution in S1-Global Project at STF/KEK	klystron, feedback, superconducting-cavity, linac	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.

MOPC157	Performance of LLRF System at S1-Global in KEK*	controls, diagnostics, klystron, cryogenics	451
	S. Michizono, D.A. Arakawa, S. Fukuda, E. Kako, H. Katagiri, T. Matsumoto, T. Miura, Y. Yano KEK, Ibaraki, Japan
	Vector-sum control was carried out at S1-Global. The rf stabilities of 0.007% in amplitude and 17 mdeg. in phase are obtained. Various diagnostics (such as on-line quench pulse detector, dynamic detuning monitor and so on) is implemented. The IF-mixture system, where 3 intermediate frequencies (IF) are used and the number of ADCs can be reduced, was used as rf waveform monitors. These monitors are used for the performance analysis. Quench phenomena observed at the high-gradient operation are also analyzed from the view point of dynamic change in loaded Q and cavity detuning during rf pulse.

MOPC160	Digital LLRF for IFMIF-EVEDA	LLRF, controls, rfq, resonance	457
	A. Salom, A. Arriaga, J.C. Calvo, I. Kirpitchev, P. Méndez, D. Regidor, M. Weber CIEMAT, Madrid, Spain A. Mosnier CEA/IRFU, Gif-sur-Yvette, France F. Pérez CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	The IFMIF-EVEDA project aims to build a prototype accelerator (deuteron, 9MeV, 125mA) to be located at Rokkasho, Japan, for design validation of the IFMIF Accelerator. CIEMAT from Madrid, Spain, is in charge of providing the RF systems for this prototype accelerator. The LLRF will adjust the phase and amplitude of the RF drive and the resonance frequency of the cavities. This paper summarizes its main characteristics and Control System integrated in EPICS. The hardware is based on a commercial FPGA board, an analog front end and a local timing system. Each LLRF system will control and diagnose two RF chains and it will handle the RF fast Interlocks (vacuum, arcs, reflected power and multipacting). A specific LLRF will be developed for the special case of the RFQ cavity, with one Master LLRF and three Slave LLRFs to feed the 8 RF chains of the cavity. The conceptual design and other capabilities of the system like automatic conditioning, frequency tuning for startup and field flatness of the RFQ, etc, will be shown in this paper together with the first low power test results of the LLRF prototype and the performance of the Control System.

MOPC161	Challenges for the Low Level RF Design for ESS	LLRF, controls, klystron, linac	460
	A.J. Johansson Lund University, Lund, Sweden R. Zeng ESS, Lund, Sweden
	The European Spallation Source (ESS) is a planned neutron source to be built in Lund, Sweden, which is planned to produce the first neutrons in 2019. It will have an average beam power at the target of 5 MW, an average current along the Linac of 50 mA, and a pulse repetition rate and length of 20 Hz and 2 ms, respectively. The Linac will have around 200 LLRF stations employed to control a variety of RF cavities such as RFQ, DTL, spoke and elliptical superconducting cavities. The challenges on LLRF systems are mainly the high demands on energy efficiency on all parts of the facility, an operational goal of 95% availability of the facility and a comparably short time from start of final design to commissioning. Running with long pulses, high current and spoke cavities also brings new challenges on LLRF design. In this paper we will describe the consequences these challenges have on the LLRF system, and the proposed solutions and development projects that have started in order to reach these demands.

MOPC163	Low-level RF Control System for the Taiwan Photon Source	LLRF, controls, low-level-rf, SRF	463
	M.-S. Yeh NSRRC, Hsinchu, Taiwan
	The low-level RF (LLRF) control system is an essential component of the RF system for Taiwan Photon Source. The LLRF control system will perform various functions including control loops for the cavity gap voltage and the phase feedback, RF system interlock protection and the diagnostics for a machine trip. The LLRF system is manufactured in house using the most recent commercial RF chips. The LLRF system has an analogue architecture similar to that used in the 1.5-GeV Taiwan Light Source (TLS). An overview of the system architecture and its functionality is presented herein.

MOPC164	Upgrade of the ISIS Synchrotron Low Power RF System	controls, feedback, ion, synchrotron	466
	A. Seville, N.E. Farthing, I.S.K. Gardner, R.J. Mathieson, J.W.G. Thomason STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom D.B. Allen STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
	The ISIS synchrotron at the Rutherford Appleton Laboratory in the UK now routinely uses a dual harmonic RF system to accelerate beam currents in excess of 230 uA to run two target stations simultaneously. In order to give more stable control of the phase of the RF voltage at each of the fundamental (1RF) and second harmonic (2RF) cavities, changes have been made to the low power RF (LPRF) control systems. In addition to this a new FPGA based master oscillator has been commissioned for the first time, and further changes using digital technologies to replace other components of the LPRF system are to be investigated. This paper reports on the LPRF hardware commissioning and reliability.

MOPC165	Digital Low Level RF Development at Daresbury Laboratory	controls, LLRF, linac, beam-loading	469
	P.A. Corlett, L. Ma, A.J. Moss STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Digital LLRF development using Field Programmable Gate Arrays (FPGAs) is a new activity at Daresbury Laboratory. Using the LLRF4 development board, designed by Larry Doolittle of Lawrence Berkeley National Laboratory, a full featured control system incorporating fast feedback loops and a feed-forward system has been developed for use on the ALICE (Accelerators and Lasers in Combined Experiments) energy recovery linac. Technical details of the system are presented, along with experimental measurements.

MOPO004	A Longitudinal Kicker Cavity for a Bunch-by-bunch Feedback System at ELSA	kicker, simulation, feedback, impedance	484
	N. Heurich, W. Hillert, A. Roth, R. Zimmermann ELSA, Bonn, Germany
	At the Electron Stretcher Facility ELSA of Bonn University, a longitudinal bunch-by-bunch feedback system is currently being installed in order to damp multibunch instabilities and to enable a future intensity upgrade of up to 200 mA. As a main component, a longitudinal kicker cavity was developed and manufactured. The kicker requires a bandwidth of 250~MHz taking into account the bunch spacing of 2 ns at ELSA. Existing designs used at other facilities were optimized in view of the considerably larger bunch lenght at ELSA. The choice of 1.125 GHz as a center frequency is a result of these considerations. With the resulting low quality factor, the design had to be optimized in order to maximize the shunt impedance. The longitudinal feedback is succesfully working with the prototype installed in the stretcher ring. The design and detailed simulations of the geometry are discussed and laboratory measurements are presented.

MOPO018	Active Beam Current Stabilization in the Cornell ERL Prototype Injector	laser, feedback, gun, cathode	523
	F. Löhl, P. Szypryt CLASSE, Ithaca, New York, USA
	In order to operate the Cornell ERL prototype injector at beam currents beyond 10 mA, the beam current has to be highly stable. The reason is that fast beam current fluctuations generate transient effects in the DC gun voltage as well as in the fields of subsequent superconducting cavities, which can lead to excessive beam loss or to trips of subsystems. Therefore, a feedback scheme was developed which uses the signal of a beam current monitor as an input, and applies appropriate corrections to a Pockels cell installed within the laser path of the photo-injector laser. In this paper, high current results achieved with this feedback scheme are presented.

MOPS015	40-80 MHz Muon Front-End for the Neutrino Factory Design Study	solenoid, factory, lattice, target	628
	G. Prior, S.S. Gilardoni CERN, Geneva, Switzerland A.E. Alexandri University of Patras, Rio, Greece
	Funding: EU FP7 EUROnu WP3. CERN summer student programme. To understand better the neutrino properties, machines able to produce an order of 10²¹ neutrinos per year have to be built. One of the proposed machine is called a neutrino factory. In this scenario, muons produced by the decay of pions coming from the interaction of a proton beam onto a target are accelerated to energies of several GeV and injected in a storage ring where they will decay in neutrinos. The so-called front-end section of the neutrino factory is conceived to reduce the transverse divergence of the muon beam and to adapt its temporal structure to the acceptance of the downstream accelerators to minimize losses. We present a re-evaluation of the muon front-end scenario which used 40-80 MHz radio-frequency cavities capturing one sign at a time in a single-bunch to bucket mode. The standard software environment of the International Study for the Neutrino Factory (IDS-NF) has been used, for comparison of its performance with the IDS-NF baseline front-end design which operates with higher frequency (330-200 MHz) capturing in a train of alternated sign the muons bunches.

MOPS030	Beam Dynamics of the FRANZ Bunch Compressor using Realistic Fields with a Focus on the Rebuncher Cavities	linac, dipole, simulation, focusing	667
	D. Noll, L.P. Chau, M. Droba, O. Meusel, H. Podlech, U. Ratzinger, C. Wiesner IAP, Frankfurt am Main, Germany
	Funding: Work supported by HIC for FAIR. The ARMADILLO bunch compressor currently being designed at IAP is capable of reaching a longitudinal pulse compression ratio of 45 for proton beams of 150 mA at 2 MeV. It will provide one nanosecond proton pulses with a peak current of 7.7 A. The system guides nine linacμbunches deflected by a 5 MHz rf kicker and uses four dipole magnets - two homogeneous and two with field gradients - to merge them on the target. For longitudinal focusing and an energy variation of ±200 keV two multitrack rf cavities are included. ARMADILLO will be installed at the end of the Frankfurt Neutron Source FRANZ making use of the unique 250 kHz time structure. This contribution will provide an overview of the layout of the system as well as recent advances in component design and beam dynamics of the compressor.

MOPS038	3D Beam Dynamic Simulation in Heavy Ion Superconducting Drift Tube Linac	simulation, focusing, ion, linac	685
	A.V. Samoshin, S.M. Polozov MEPhI, Moscow, Russia
	The superconducting (SC) linac conventionally consists of some different classes of the identical cavities. Each cavity is based on a SC structure with a high accelerating gradient. The low charge state beams require stronger transverse focusing. This focusing can be reached with the help of SC solenoid lenses. In this paper beam dynamics simulation obtain by smooth approximation and full field. Traditionally only the Coulomb field is taken into account for low energy beams. In this paper the computer simulation of heavy ion beam dynamics in superconducting (SC) linac will carried out by means of the "particle-in-cell" method. Simulation results will present.

MOPS047	Studies of Transverse Single-pass Beam Breakup in E-Linac	HOM, linac, dipole, emittance	706
	D. Kaltchev, R.A. Baartman, Y.-C. Chao, P. Kolb, S.R. Koscielniak, L. Merminga, A.K. Mitra, V. Zvyagintsev TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	Time-domain simulations of single-pass transverse beam-breakup (BBU) effects in E-linac are described. We use dipole-HOM parameters for the 9-cell cavity obtained with Particle Studio to evaluate the rms bunch orbit offsets at linac exit. Finding the multi-bunch orbit contribution to machine emittance as a function of the average beam current allows to evaluate the performance of two cavity models for two different modes of machine operation.

MOPS051	Modeling of the Beam Break Up Instability for BERLinPro*	linac, optics, solenoid, HOM	718
	Y. Petenev, A.V. Bondarenko, A.N. Matveenko HZB, Berlin, Germany
	Following funding approval late 2010, Helmholtz-Zentrum Berlin officially started Jan. 2011 the design and construction of the Berlin Energy Recovery Linac Project BERLinPro. The initial goal of this compact ERL is to develop the ERL accelerator physics and technology required to accelerate a high-current low emittance beam. In this work the threshold current of the Beam Break Up (BBU) instability was calculated for the BERLinPro. The comparison of two 100 MeV linacs based on different type of superconducting cavities is made. Different methods of BBU suppression are investigated (e.g. the influence of solenoid, pseudo-reflector and quadruple triplets in the linac structure on the BBU threshold).

MOPS066	Collective Effects in the MAX IV 3 GeV Ring	impedance, damping, storage-ring, synchrotron	754
	P.F. Tavares MAX-lab, Lund, Sweden T.F. Günzel CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain R. Nagaoka SOLEIL, Gif-sur-Yvette, France
	We present calculations of collective instability effects in the 3 GeV electron storage ring of the MAX IV facility currently under construction in Lund, Sweden. The storage ring is designed to deliver ultra-low emittance down to 0.24 nm rad so as to provide high brightness synchrotron radiation from undulators. This is achieved in a comparatively small machine (528 m circumference) through the use of a multi-bend achromat lattice and a compact magnet design featuring multi-purpose narrow gap magnet blocks. This design features small dispersion leading to low momentum compaction, which, together with the small circular (11 mm radius) chambers, poses a challenge to reach the design current (500 mA in 176 bunches) without exciting instabilities and degrading beam parameters due to the interaction with the machine impedance. Particularly important are multi-bunch resistive wall effects in the NEG coated copper chamber as well single-bunch instabilities driven by the broad-band impedance. A low RF frequency (100 MHz) and harmonic cavities are foreseen to lengthen the bunches and increase instability thresholds.

MOPS080	Comparison of the Current LHC Collimators and the SLAC Phase 2 Collimator Impedances	impedance, coupling, simulation, collimation	790
	H.A. Day, R.M. Jones UMAN, Manchester, United Kingdom F. Caspers, H.A. Day, E. Métral, B. Salvant CERN, Geneva, Switzerland
	One of the key sources of transverse impedance in the LHC has been the secondary graphite collimators that sit close to the beam at all energies. This limits the stable bunch intensity due to transverse coupled-bunch instabilities and transverse mode coupling instability. To counteract this, new secondary collimators have been proposed for the phase II upgrade of the LHC collimation system. A number of designs based on different jaw materials and mechanical designs have been proposed. A comparison of the beam coupling impedance of these different designs derived from simulations are presented, with reference to the existing phase I secondary collimator design.

MOPS082	Some Considerations on the Choice of Frequency and Geometrical Beta in High Power Proton Linacs in the Context of Higher Order Modes	HOM, linac, simulation, proton	793
	M. Schuh, F. Gerigk CERN, Geneva, Switzerland M. Schuh MPI-K, Heidelberg, Germany C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Several high power superconducting (SC) proton linear accelerators are currently in the design stage around the world, such as for example the European Spallation Source (ESS) in Lund, Project X at Fermilab, the European ADS demonstrator MYRRAH in Mol and the Superconducting Proton linac (SPL) at CERN. In this contribution, the influence of Higher Order Modes (HOMs) in elliptical SC cavities is discussed as a function of the operation frequency, the number of cells and the geometrical beta of the cavity. Based on cavity design data beam dynamics simulations are executed for different linac layouts to quantify the influence of HOMs.

MOPS086	Beam Breakup Simulation for the PEP-X ERL	HOM, emittance, simulation, recirculation	805
	Y. Jiao, Y. Cai, A. Chao SLAC, Menlo Park, California, USA
	Funding: The work is supported by the U.S. Department of Energy under contract No. DE-AC02-76SF00515. The transverse beam breakup (BBU) is one of the dominant factors in ERL for the available beam current. A tracking code built in Matlab is developed and benchmarked by comparing with the analytical solutions with the simple model. Study on the threshold current and emittance growth due to the transverse BBU for PEP-X ERL are presented in this paper.

MOPZ007	A Non-scaling Fixed Field Alternating Gradient Accelerator for the Final Acceleration Stage of the International Design Study of the Neutrino Factory	kicker, extraction, injection, lattice	832
	J.S. Berg BNL, Upton, Long Island, New York, USA M. Aslaninejad, J. Pasternak Imperial College of Science and Technology, Department of Physics, London, United Kingdom N. Bliss, M.A. Cordwell, T.J. Jones STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom A.A. Muir STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom H. Witte JAI, Oxford, United Kingdom
	Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The International Design Study of the Neutrino Factory (IDS-NF) has recently completed its Interim Design Report (IDR), which presents our current baseline design of the neutrino factory. To increase the efficiency and reduce the cost of acceleration, the IDR design uses a linear non-scaling fixed field alternating gradient accelerator (FFAG) for its final acceleration stage. We present the current lattice design of that FFAG, including the main ring plus its injection and extraction systems. We describe parameters for the main ring magnets, kickers, and septa, as well as the power supplies for the kickers. We present a first pass at an engineering layout for the ring and its subsystems.

MOPZ009	The Muon Linac for the International Design Study for the Neutrino Factory	linac, cryomodule, factory, lattice	838
	A. Kurup, M. Aslaninejad, C. Bonţoiu, J.K. Pozimski Imperial College of Science and Technology, Department of Physics, London, United Kingdom K.B. Beard Muons, Inc, Batavia, USA S.A. Bogacz, V.S. Morozov JLAB, Newport News, Virginia, USA
	The first stage of muon acceleration in the Neutrino Factory utilises a superconducting linac to accelerate muons from 244 MeV to 900 MeV. The linac is split into three types of cryomodules with decreasing magnetic fields and increasing amounts of RF voltage but with the design of the superconducting solenoid and RF cavities being the same for all cryomodules. The current status of the muon linac for the International Design Study for the Neutrino Factory will be presented including a final lattice design of the linac; electromagnetic simulations; and a preliminary cost estimate.

Paper

Title

Other Keywords

Page

MOYBA01

Present Status of the ILC Project and Developments

linac, linear-collider, collider, electron

16

M.C. Ross
Fermilab, Batavia, USA
N.J. Walker
DESY, Hamburg, Germany
A. Yamamoto
KEK, Ibaraki, Japan

Funding: FNAL is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The Technical Design of the ILC Project will be finished in late 2012. The Technical Design Report will include a description of the updated design, with a cost estimate and a project plan, and the results of R & D done in support of the ILC. Results from directed ILC R & D are used to reduce the cost and risk associated with the ILC design. We present a summary of key challenges and show how the global R & D effort has addressed them. The most important activity has been in pursuit of very high gradient superconducting RF linac technology. There has been excellent progress toward the goal of practical industrial production of niobium sheet-metal cavities with gradient performance in excess of 35 MV/m. In addition, three purpose-built beam test facilities have been constructed and used to study and demonstrate high current linac performance, electron-cloud beam dynamics and precision beam control. The report also includes a summary of component design studies and conventional facilities cost optimization design studies.

Slides MOYBA01 [9.755 MB]

MOOCA01

Production and Testing Experience with the SRF Cavities for the CEBAF 12 GeV Upgrade

cryomodule, HOM, SRF, higher-order-mode

26

A. Burrill, G.K. Davis, F. Marhauser, C.E. Reece, A.V. Reilly, M. Stirbet
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The CEBAF recirculating CW electron linear accelerator at Jefferson Lab is presently undergoing a major upgrade to 12 GeV. This project includes the fabrication, preparation, and testing of 80 new 7-cell SRF cavities, followed by their incorporation into ten new cryomodules for subsequent testing and installation. In order to maximize the cavity Q over the full operable dynamic range in CEBAF (as high as 25 MV/m), the decision was taken to apply a streamlined preparation process that includes a final light temperature-controlled electropolish of the rf surface over the vendor-provided bulk BCP etch. Cavity processing work began at JLab in September 2010 and will continue through December 2011. The excellent performance results are exceeding project requirements and indicate a fabrication and preparation process that is stable and well controlled. The cavity production and performance experience to date will be summarized and lessons learned reported to the community.

Slides MOOCA01 [4.376 MB]

MOOCA03

Updates to the International Linear Collider Damping Rings Baseline Design

lattice, damping, electron, positron

32

S. Guiducci, M.E. Biagini
INFN/LNF, Frascati (Roma), Italy
G. Dugan, M.A. Palmer, D. L. Rubin
CLASSE, Ithaca, New York, USA
J. Gao, D. Wang
IHEP Beijing, Beijing, People's Republic of China
M.T.F. Pivi, Y. Sun
SLAC, Menlo Park, California, USA
J. Urakawa
KEK, Ibaraki, Japan

A new baseline design for the International Linear Collider (ILC) damping rings has been adopted which reduces the ring circumference to 3.2 km from 6.4 km. This design change is associated with a revised plan to operate the ILC with one half the beam current originally specified in the ILC Reference Design Report. We describe the new layout and lattice that has been developed for the shorter ring. In addition, we discuss features of the new design that will allow operation at a 10Hz repetition rate which is twice the rate specified for baseline operation. Finally, we examine the implications for restoring operation with the originally specified beam current while maintaining the smaller ring circumference.

Slides MOOCA03 [2.381 MB]

MOODA01

Experience with the Cornell ERL Injector SRF Cryomodule during High Beam Current Operation

HOM, SRF, cryomodule, damping

35

M. Liepe, D.L. Hartill, G.H. Hoffstaetter, S. Posen, P. Quigley, V. Veshcherevich
CLASSE, Ithaca, New York, USA

Funding: Supported by NSF award DMR-0807731
Cornell University has developed and fabricated a SCRF injector cryomodule for the acceleration of high current, low emittance CW beams. This cryomodule is based on superconducting RF technology with five 2-cell SRF cavities operated in CW mode. Strong Higher-Order-Mode (HOM) damping and high power RF input couplers support accelerating beam currents of tens of mA. The cryomodule is currently under extensive testing in the Cornell ERL injector prototype with CW beam currents exceeding 25 mA. This paper gives an overview of the experience gained during the high beam current operation of the cryomodule, with a focus on the intrinsic cavity quality factors, input coupler performance, and HOM damping.

MOODA02

S1-Global Module Tests at STF/KEK

cryomodule, SRF, feedback, linac

38

D. Kostin, K. Jensch, L. Lilje, A. Matheisen, W.-D. Möller, P. Schilling, M. Schmökel, N.J. Walker, H. Weise
DESY, Hamburg, Germany
C. Adolphsen, C.D. Nantista
SLAC, Menlo Park, California, USA
M. Akemoto, S. Fukuda, K. Hara, H. Hayano, N. Higashi, E. Kako, H. Katagiri, Y. Kojima, Y. Kondo, T. Matsumoto, H. Matsushita, S. Michizono, T. Miura, H. Nakai, H. Nakajima, K. Nakanishi, S. Noguchi, N. Ohuchi, T. Saeki, M. Satoh, T. Shidara, T. Shishido, T. Takenaka, A. Terashima, N. Toge, K. Tsuchiya, K. Watanabe, S. Yamaguchi, A. Yamamoto, Y. Yamamoto, K. Yokoya
KEK, Ibaraki, Japan
T.T. Arkan, S. Barbanotti, M.A. Battistoni, H. Carter, M.S. Champion, A. Hocker, R.D. Kephart, J.S. Kerby, D.V. Mitchell, T.J. Peterson, Y.M. Pischalnikov, M.C. Ross, W. Schappert, B.E. Smith
Fermilab, Batavia, USA
A. Bosotti, C. Pagani, R. Paparella, P. Pierini
INFN/LASA, Segrate (MI), Italy

S1-Global collaborative effort of INFN, DESY, FNAL, SLAC and KEK, recently successfully finished at KEK as a part of ILC GDE, is an important milestone for the ILC. International collaboration of three regions, Asia, North America and Europe, proved to be efficient on the construction and cold tests of the accelerating module consisting of 8 SRF cavities; 2 from FNAL, 2 from DESY and 4 from KEK. Three different cavity tuning systems were tested together with two types of high power couplers. The module was cooled down three times which enabled extensive high power tests with cavities, performance limits investigation, Lorentz force detuning tests, simultaneous multiple cavities operation and other activities such as an operation test of distributed RF scheme with low level RF feedback. The results of this S1-Global module test are presented and discussed.

Slides MOODA02 [2.982 MB]

MOODA03

First Characterization of a Fully Superconducting RF Photoinjector Cavity

cathode, laser, linac, solenoid

41

A. Neumann, W. Anders, R. Barday, A. Jankowiak, T. Kamps, J. Knobloch, O. Kugeler, A.N. Matveenko, T. Quast, J. Rudolph, S.G. Schubert, J. Völker
HZB, Berlin, Germany
P. Kneisel
JLAB, Newport News, Virginia, USA
R. Nietubyc
The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock, Poland
J.K. Sekutowicz
DESY, Hamburg, Germany
J. Smedley
BNL, Upton, Long Island, New York, USA
V. Volkov
BINP SB RAS, Novosibirsk, Russia
G. Weinberg
FHI, Berlin, Germany
I. Will
MBI, Berlin, Germany

As a first step towards a high brightness, high average current electron source for the BERLinPro ERL a fully superconducting photo-injector was developed by HZB in collaboration with JLab, DESY and the A. Soltan Institute. This cavity-injector ensemble is made up of a 1.6-cell superconducting cavity with a superconducting lead cathode deposited on the half-cell backwall. A superconducting solenoid is used for emittance compensation. This system, including a diagnostics beamline, has been installed in the HoBiCaT facility to serve as a testbed for beam dynamics studies and to test the combination SRF cavity and superconducting solenoid. This paper summarizes the characterization of the cavity in this configuration including Q measurements, dark current tests and field-stability analyses.

Slides MOODA03 [10.343 MB]

MOOCB02

Commissioning and Performance of the Beam Monitor System for XFEL/SPring-8 “SACLA”

electron, undulator, bunching, FEL

47

Y. Otake, C. Kondo, H. Maesaka
RIKEN Spring-8 Harima, Hyogo, Japan
H. Ego, S. Matsubara, T. Matsumoto, T. Sakurai, H. Tomizawa, K. Yanagida
JASRI/SPring-8, Hyogo-ken, Japan
S.I. Inoue
SES, Hyogo-pref., Japan

The construction of a beam monitor system for XFEL/SPring 8 “SACLA” was completed. The system was developed to realize a spatial resolution of less than 3 um to align a beam orbit for an undulator section with about 100 m long and a temporal resolution to measure bunch lengths from 1 ns to 30 fs to maintain a constant peak beam current conducting stable SASE lasing. The system principally comprises cavity type beam position monitors (BPM), current monitors (CT), screen monitors (SCM) and bunch length measurement instruments, such as an rf deflector and CSR detectors. Commissioning of SACLA started from March 2011, and the monitors performed sufficient roles to tune beams for the lasing. The achieved over-all performances of the system including DAQ are: the BPM have spatial resolution of 300 nm, the bunch length monitors observe bunch lengths from 1ns in an injector with velocity bunching to less than 30 fs after three-stage bunch compressors. The less than a 3 um spatial resolution of the SCM was also confirmed in practical beam operation. By these fulfilled performances, the stable lasing of SACLA will be achieved. This report describes commissioning, performance of the system.

Slides MOOCB02 [7.516 MB]

MOODB02

RF Modeling Plans for the European Spallation Source

HOM, electron, beam-losses, linac

56

S. Molloy, M. Lindroos, S. Peggs
ESS, Lund, Sweden
R. Ainsworth
Royal Holloway, University of London, Surrey, United Kingdom
R.J.M.Y. Ruber
Uppsala University, Uppsala, Sweden

The European Spallation Source (ESS) will be the world's most powerful next generation neutron source. The ESS linac is designed to accelerate highly charged bunches of protons to a final energy of 2.5 GeV, with a design beam power of 5 MW, for collision with a target used to produce the high neutron flux. In order to achieve this several stages of RF acceleration are required, each using a different technology. The high beam current and power require a high degree of control of the accelerating RF, and the specification that no more than 1 W/m of losses will be experienced means that the excitation and decay of the HOMs must be very well understood. Experience at other high power machines also implies that an understanding of the generation and subsequent trajectories of any field-emitted electrons should be understood. Thermal detuning of the HOM couplers due to multipacting is a serious concern here. This paper will outline the RF modeling plans - including the construction of mathematical models, simulations of HOMs, and multipacting - during the current Accelerator Design Update phase, and will discuss several of the more important issues for ESS.

Slides MOODB02 [48.641 MB]

MOPC004

352.2 MHz HOM Damped Normal Conducting ESRF Cavity: Design and Fabrication

HOM, coupling, vacuum, storage-ring

68

V. Serrière, A.K. Bandyopadhyay, D. Boilot, L. Goirand, J. Jacob, B. Ogier, A. Triantafyllou
ESRF, Grenoble, France

Funding: This work, carried out within the framework of the ESRFUP project, has received research funding from the EU Seventh Framework Programme, FP7.
The ongoing ESRF upgrade included an option for an increase of the storage ring current from 200 to 300 mA, which has been tested successfully with the existing RF system. At this current level the HOM tuning of the existing five-cell copper cavities becomes extremely delicate and in view of a future reliable operation in user mode, new HOM free normal conducting cavities were developed at the ESRF. The design is based on the existing BESSY/ALBA cavity. However, several substantial modifications have been implemented and different fabrication processes elaborated to improve the design. Three operational prototypes will be delivered by three manufacturers in the coming months and will be fully tested on the ring. Although the 300 mA option has finally not been retained for the first phase of the ESRF upgrade, the aim is now to validate the new cavity design for a possible later increase in current.

MOPC005

352.2 MHz – 150 kW Solid State Amplifiers at the ESRF

booster, klystron, HOM, power-supply

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.

MOPC006

A Coupled RFQ-IH Combination for the Neutron Source FRANZ

rfq, DTL, coupling, proton

74

M. Heilmann, O. Meusel, D. Mäder, U. Ratzinger, A. Schempp
IAP, Frankfurt am Main, Germany

Funding: HIC for FAIR
The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum is driven by a 2 MeV proton linac consisting of a 4-rod-radio-frequency-quadrupol (RFQ) and an 8 gap IH-DTL structure. RFQ and IH cavity will be powered by only one radio frequency (RF) amplifier to reduce costs. The RF-amplifier of the RFQ-IH combination is coupled into the RFQ. Internal inductive coupling along the axis connects the RFQ with the IH cavity ensuring the required power transition as well as a fixed phase relation between the two structures. The main acceleration of 120 keV up to 2.03 MeV will be reached by the RFQ-IH combination with 175 MHz and at a total length of 2.3 m. The losses in the RFQ-IH combination are about 200 kW.

MOPC007

Cold Photocathode RF Gun

gun, vacuum, cathode, cryogenics

77

V. Vogel, K. Flöttmann, S. Schreiber
DESY, Hamburg, Germany

Heating and thermal expansion in the normal conductivity RF-photo electron gun, are the main limitations to achieve high accelerating gradient and consequently a low emittance beam. Some pure materials show a significant increase in thermal conductivity with a small coefficient of temperature expansion at temperatures around 20 degrees Kelvin. Possible materials are Molybdenum, Iridium or Tungsten. However, machining of these materials is very difficult. Therefore we propose a simplified shape for an L-band RF gun. We expect to achieve a significant increase in gradient for similar RF powers as used in the present DESY RF-gun. On the other hand, it would also be possible to increase the duty cycle keeping a moderate gradient. In this report we discuss one possible design of an RF-gun using hard metals and present simulations on thermal properties.

MOPC010

Phase-Modulation SLED Operation Mode at Elettra

linac, LLRF, klystron, target

83

C. Serpico, P. Delgiusto, A. Fabris, F. Gelmetti, M.M. Milloch, A. Salom, D. Wang
ELETTRA, Basovizza, Italy

FERMI@Elettra is the soft X-ray, fourth generation light source facility at the Elettra Laboratory in Trieste, Italy. It is based on a seeded FEL, driven by a normal conducting linac that is presently expected to operate at 1.5 GeV. The last seven backward traveling wave structures have been equipped with a SLED system. Due to breakdown problems inside the sections, that was the result of high peak fields generated during conventional SLED operation, the sections experienced difficulties in reaching the desired gradients. To lower the peak field and make the compressed pulse “flatter”, phase-modulation of the SLED drive power will be implemented. A description of the phase modulation of the drive power and the results achieved will be reported in the following paper.

MOPC014

RF Processing of L-band RF Gun for KEK-STF

gun, cathode, laser, solenoid

92

M. Kuriki, H. Iijima, Y.M. Masumoto
HU/AdSM, Higashi-Hiroshima, Japan
H. Hayano, H. Sugiyama, J. Urakawa, K. Watanabe
KEK, Ibaraki, Japan
G. Isoyama, R. Kato
ISIR, Osaka, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
Y. Takahashi
Sokendai, Ibaraki, Japan

Funding: This work is supported by MEXT Quantum Beam Technology Program, KEK Promotion of collaborative research programs in universitie.
KEK STF (Superconducting Test Facility) is established for developing super-conducting accelerator technology for ILC (International Linear Collider). At KEK-STF, accelerator operation with a beam loading is planned in 2013. An electron injector based on L-band Photo-cathode RF gun is now being developed. A L-band RF gun designed by DESY and fabricated by FNAL has been placed in KEK-STF and RF processing was carried out. The results of the RF processing and status of STF injector will be presented.

MOPC015

S-band Vacuum Isolator and Circulator for Injector System of SPring-8 Linac

vacuum, linac, insertion, injection

95

T. Taniuchi, H. Hanaki, S. Suzuki
JASRI/SPring-8, Hyogo-ken, Japan
A. Miura, K. Shinohara, S. Tsuruoka
Nihon Koshuha Co. Ltd, Yokohama, Japan

A pressurized sulfur hexafluoride (SF6) waveguide system at an injector section of SPring-8 linac, will be replaced with a vacuum waveguide system in order to renew aged equipments and improve a phase stability. For this renewal, RF isolator and a circulator operated in vacuum, are newly developed. High power RF test for these components were performed and a good result for RF and vacuum characteristics were obtained.

MOPC016

Development of a New RF Accelerating Cavity for J-PARC Ring Accelerator

simulation, impedance, ion, controls

98

Y. Morita, T. Kageyama
KEK, Ibaraki, Japan
J. Kameda
ICRR, Chiba, Japan
S. Yamashita
ICEPP, Tokyo, Japan

Funding: Japan Society for the Promotion of Science (JSPS)
To enhance the beam power delivered by the J-PARC* ring accelerators, upgrading the accelerating cavities is indispensable. In particular, long term stable operation of the present cavities for the RCS** is one of the important issues. Currently, the cavities are loaded with FINEMET*** cores cooled by water, where every core is coated with glass cloth and epoxy resin for waterproof. However, it was reported that some of the cores were damaged by thermal stress. We are developing a new cavity loaded with multi ring core modules. Each core module consists of three ring cores concentrically arranged and sandwiched between two glass epoxy plates with flow channels grooved. The ring cores without waterproof coating are cooled by the turbulent flow of a chemically inert liquid (Fluorinert), since FINEMET is subject to corrosion in water. We have designed and built a high power prototype cavity loaded with a single core module, then carried out low level measurement and high power test. Finally, the cavity has been stably operated up to an average power loss of 10 kW per core module, which is 1.7 times higher than that for the present RCS cavity.
*Japan Proton Accelerator Research Complex
**Rapid-Cycling Synchrotron
***FINEMET is an iron-based magnetic alloy produced by Hitachi Metals, Ltd..

MOPC017

Thermal Analyses of an RF Input Coupler for the IFMIF/EVEDA RFQ Linac

rfq, coupling, linac, beam-transport

101

S. Maebara
JAEA, Ibaraki-ken, Japan

In the design of prototype RFQ linac for the IFMIF/EVEDA Project, a coupled cavity type of RFQ, which has a longitudinal length of 9.78m, was proposed to accelerate deuteron beam up to 5MeV. The operation frequency of 175MHz was selected to accelerate a large current of 125mA in CW mode. The driving RF power of 1.28 MW by 8 RF input couplers has to be injected to the RFQ cavity. As the RF input coupler design, RF losses including a loop antenna and an RF vacuum window, based on a 6 1/8 inch co-axial waveguide were calculated. In this conference, these results and thermal analysis results in CW operation mode will be presented in details.

MOPC019

Condition of MA Cut Cores in the RF Cavities of J-PARC Main Ring after Several Years of Operation

impedance, resonance, ion, synchrotron

107

M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan
E. Ezura, K. Hasegawa, K. Takata
KEK, Tokai, Ibaraki, Japan
K. Hara, C. Ohmori, M. Toda, M. Yoshii
KEK/JAEA, Ibaraki-Ken, Japan
T. Sato, M. Yamamoto
JAEA, Ibaraki-ken, Japan

J-PARC 3 GeV RCS and 50 GeV Synchrotron (MR) employ RF cavities loaded with Magnetic Alloy (MA) cores to generate a high field gradient. The RF cavities in RCS use MA un-cut cores. On the other hand, the RF cavities in MR employ MA cut cores to increase the Q-value from 0.6 to 26. We observed the impedance reductions of all MR RF cavities during several years operation. Opening the RF cavities, we found that the impedance reductions were resulting from corrosion on the cut and polished surfaces of MA cores. Before installation of the RF cavities, we had 1000 and 2000 hours long tests at a test stand. We didn't observe the impedance reduction related to the corrosion on the MA core cut surfaces at the test stand. The only difference between the test stand and MR is the quality of cooling water. The MR cooling water contains copper ions for example from copper hollow conductors of the main magnets. We report the influence of the copper ions to the corrosion on the MA core cut surface. We also show plans how to solve the issue of MA core cut surface corrosion.

MOPC020

Development of an S-band Multi-cell Accelerating Cavity for RF Gun and Booster Linac

gun, booster, linac, electron

110

T. Aoki, K. Sakaue, M. Washio
RISE, Tokyo, Japan
A. Deshpande
SAMEER, Mumbai, India
M.K. Fukuda, N.K. Kudo, T. Takatomi, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Funding: Work supported by JST Quantum Beam Program
We have been developing a photocathode rf gun. The rf gun with multi cell can produce a high energy electron beam, so it may be used for numerous applications such as medicine and industry. At Laser Undulator Compact X-ray source (LUCX), we have developed a compact X-ray source based on inverse Compton scattering. Using a multi cell rf gun will make possible for the X-ray source to use for such applications. S-band 3.5 cell rf electron gun which is 20 cm long can produce more than 10 MeV electron beam. According to the simulation, it is said that the emittance of 3.5 cell rf gun is as low as that of 1.6 cell rf gun. The electromagnetic design has been performed with the code SuperFish, and the particle tracing by Parmela. The new rf gun is already installed and produced a high quality electron beam with energy of more than 10 MeV. As a consequence of the substantial efforts of developing rf cavity, we decide to make a compact RF accelerating structure with more cell for achieving a smaller system. The measurement results of using the 3.5 cell rf gun, the design of 12 cell booster cavity, and current status of 12 cell cavity manufacturing will be presented at the conference.

MOPC024

Construction Status of the CPHS RFQ at Tsinghua University

rfq, quadrupole, dipole, vacuum

122

Q.Z. Xing, Y.J. Bai, J.C. Cai, C. Cheng, L. Du, T. Du, X. Guan, Q. Qiang, X.W. Wang, Z.F. Xiong, S.Y. Yang, H.Y. Zhang, S.X. Zheng
TUB, Beijing, People's Republic of China
J.H. Billen
TechSource, Santa Fe, New Mexico, USA
W.Q. Guan, Y. He, J. Li
NUCTECH, Beijing, People's Republic of China
J. Stovall
CERN, Geneva, Switzerland
L.M. Young
AES, Medford, NY, USA

Funding: Work supported by the “985 Project” of the Ministry of Education of China.
We present, in this paper, the construction status of a Radio Frequency Quadrupole (RFQ) accelerator for the Compact Pulsed Hadron Source (CPHS) at Tsinghua University. The 3-meter-long RFQ will deliver 3 MeV protons to the downstream Drift Tube Linac (DTL) with the peak current of 50 mA, pulse length of 0.5 ms and beam duty factor of 2.5%. The RFQ has been mechanically separated into three sections. A ball-end mill, instead of a forming cutter, is adopted to machine the vane tip due to its varying radius of curvature. The precision of the numerically controlled milling machine has been verified by machining test pieces of aluminum and copper. Fine machining of the vanes was completed in July, 2011. The pre-braze tuning was completed at the beginning of this August.

MOPC026

MA Cavity for HIRFL-CSR

impedance, simulation, plasma, radio-frequency

125

L.R. Mei, Z. Xu, Y.J. Yuan, H.W. Zhao
IMP, Lanzhou, People's Republic of China

To meet the requirements of conducting high energy density physics and plasma physics research at HIRFL-CSR. The higher accelerating gap voltage was required. A magnetic alloy (MA)-core loaded radio frequency (RF) cavity which can provide higher accelerating gap voltage has been studied in Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS), Lanzhou. To select proper MA material to load the RF cavity, measurement for MA cores has been conducted. The MA core with higher shunt impedance and lower than 1 quality factor (Q value) should be selected. The theoretical calculation and simulation for the MA-core loaded RF cavity can be consistent with each other well. Finally 1000kW power was needed to meet 50-kV accelerating gap voltage by calculation.

MOPC031

Performance of a 13 MHz Cavity for an RF Implanter at PEFP*

coupling, ion, ion-source, simulation

136

T.A. Trinh
UST, Daejeon, Republic of Korea
Y.-S. Cho, J.-H. Jang, D.I. Kim, H.S. Kim, H.-J. Kwon, B.-S. Park, K.T. Seol
KAERI, Daejon, Republic of Korea

Funding: This work is supported by the Ministry of Education, Science and Technology of the Korean Government
A 13 MHz - normal conducting cavity for an rf implanter has been successfully developed at PEFP (Proton Engineering Frontier Project). It consists of an inductive coil, accelerating electrodes and a ground electrode for the inductor. Quality factor of 2074 and critical coupling were achieved at resonant frequency of 12.658 MHz. Rf power of 1 kW was forwarded to the cavity without any spark in the cavity. Beam test was then carried out with a 27 keV helium beam generated from a Duoplasmatron ion source. The results showed that the helium beam was accelerated to final energy of 120 keV with energy spread of 1%. Detail experiments and results are addressed in this presentation.

MOPC033

The Status of a 1.6-cell Photocathode RF Gun at PAL

gun, klystron, emittance, cathode

142

M.S. Chae, J.H. Hong, I.S. Ko, Y.W. Parc
POSTECH, Pohang, Kyungbuk, Republic of Korea
S.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

The RF power conditioning of the photocathode RF gun with four holes at the side of the full cell named as 'Pohang gun' is in progress. The first goal of the conditioning is the operation of the gun with RF pulse width of 1.5 μm, repetition rate of 30 Hz, field gradient at the cathode of 130 MV/m. We operated the RF gun successfully with the conditions within last few months. It was first operational experience with such conditions in PAL. Now we have a plan to operate RF gun with higher repetition rate up to 60 Hz.

MOPC035

Design and Machine Features of 2.2-m C-band Accelerating Structure

accelerating-gradient, linac, vacuum, electron

148

C.H. Yi, M.-H. Cho, S.H. Kim, H. Lee
POSTECH, Pohang, Kyungbuk, Republic of Korea
W. Namkung
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This work is partly supported by the MEST, Korea and POSTECH BK21 Program. And this work was supported by the Korea Student Aid Foundation (KOSAF) grant funded by the Korea government.
A compact linac system is designed using a longer accelerating column in a C-band linac. It reduces the total number of RF units for the given linac beam energy and results in the cost-effective use of RF powers. For the 10 GeV PAL-XFEL project, a C-band accelerating column of 2.2-m long is investigated, which is 22% longer than 1.8-m for the SACLA at SPring-8. The detailed RF and thermal characteristics are presented by an analytic model.

MOPC036

Design of RF Cavity for Compact 9 MeV Cyclotron

cyclotron, simulation, resonance, acceleration

151

H.S. Song, J.-S. Chai, H.W. Kim, B.N. Lee, J.H. Oh
SKKU, Suwon, Republic of Korea

The number of PET facility is rapidly increasing worldwide. To get PET image, circular accelerator such as cyclotron is needed. Compact 9 MeV H-cyclotron, which has a diameter of 1.25m is being designed at Sungkyunkwan University starting from July 2010 for getting F-18. It is expected to be constructed by next year. In this paper, RF system of 9 MeV cyclotron including design processes and detail analysis of result is reported. RF system mainly describes RF cavity design.

MOPC040

The Measurement of Transversal Shunt Impedance of RF Deflector

impedance, simulation, dipole, emittance

163

A.Yu. Smirnov, M.V. Lalayan, N.P. Sobenin
MEPhI, Moscow, Russia
A.A. Zavadtsev
Nano, Moscow, Russia

This paper presents the results of transverse shunt impedance measurement performed using field perturbation technique and comparison with numerical MWS simulations. The structure under test is the S-band 3-cell deflecting cavity. The mentioned cavity operates with a dipole TM11-like mode with a phase shift of 120 deg per cell. The analyses were carried out with use of two types of perturbing beads: dielectric beads and metallic rings. The latter type perturbs the on-axis magnetic field much stronger than the electric field, which allows us calculating transversal shunt impedance using on-axis EM fields values.

MOPC041

Cross-Field Multipactor Discharge in the X-Band Cylindrical Cavity

multipactoring, electron, vacuum, radiation

166

S.V. Kuzikov, E.V. Ilyakov, I.S. Kulagin, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia
D. Lee
NSRRC, Hsinchu, Taiwan

The paper represents the experimental study of one-sided cross-field multipactor discharge in the copper cavity with the operating mode TM01 in external DC magnetic field. It was shown that discharge is very sensible to magnitudes of the external magnetic field and rf fields as well. At proper fields the multipactor discharge can be developed for 15 ns and the electron concentration can be comparable with critical one for the given rf frequency. As a result of discharging, the cavity changes its own resonant frequency and can play a role of a switch which can substitute full transmission by full reflection. Switching parameters could be controlled by DC magnetic field as well as by additional rf radiation at different frequency than operating frequency. The high rf absorption of multipactor discharge also can be used in electrically controlled powerful loads and attenuators.

MOPC043

Electromagnetic Simulations of the Input Power Couplers for the ESS-Bilbao RFQ

rfq, linac, vacuum, radio-frequency

172

O. Gonzalez, I. Bustinduy, N. Garmendia, J.L. Munoz, A. Velez
ESS Bilbao, Bilbao, Spain
F.J. Bermejo
Bilbao, Faculty of Science and Technology, Bilbao, Spain
V. Etxebarria, J. Portilla
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain

An input power system is currently being designed at ESS-Bilbao in order to inject the RF power provided by a klystron into the RFQ as part of the linac. In this work, some input power couplers based on a coaxial topology are carefully studied from an electromagnetic point of view. As we will show, the electrical properties of the ceramic window used to ensure the vacuum of the RFQ crucially deteriorates the matching of the devices. To overcome this drawback, a full-wave electromagnetic simulator is used to optimize the coupler dimensions in order to minimize both the return and insertion losses.

MOPC045

Commissioning of the ALBA Storage Ring RF System

LLRF, storage-ring, HOM, pick-up

178

F. Pérez, B. Bravo, A. Salom, P. Sanchez
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

ALBA is a 3 GeV, 400 mA, 3rd generation Synchrotron Light Source that is under commissioning in Cerdanyola, Spain. The RF System has to provide 3.6 MV of accelerating voltage and restore up to 540 kW of power to the electron beam. For that six RF plants, working at 500 MHz, are foreseen. The RF plants include several new developments: DAMPY cavity; the normal conducting HOM damped cavity developed by BESSY and based in the EU design; six are installed. CaCo; a cavity combiner to add the power of two 80 kW IOTs to produce the 160 kW needed for each cavity. WATRAX; a waveguide transition to coaxial, specially designed to feed the DAMPY cavities due to the geometrical and cooling constrains. Digital LLRF; fully designed at ALBA using commercial components. This paper shortly describes these systems and reports their performance during the ALBA commissioning.

MOPC046

CaCo: A Cavity Combiner for IOTs Amplifiers

simulation, storage-ring, high-voltage, HOM

181

B. Bravo, F. Mares, F. Pérez, P. Sanchez
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
M.L. Langlois
ESRF, Grenoble, France

The ALBA storage ring uses six room temperature cavities; each one fed by two 80 kW IOTs amplifiers at 499.654 MHz. The power of the pair of transmitters is combined by a cavity combiner, CaCo. One of the design requirements of CaCo was that it continued working safely and with a good efficiency in the case of an IOT failure (asymmetrical mode). During the first asymmetric full power tests, in May 2010, with an active IOT and the other passive, the result was dramatic, the passive IOT broke in two parts after few hours of operation. This paper presents the experimental results and the electromagnetic field simulations of the asymmetrical operation mode of CaCo, i.e. one active IOT and the other passive, and analyze why the ceramic of the output tube of the passive IOT broke during the first performance of this mode. Also, it reports a possible solution to solve this problem.

MOPC047

RF Design of the Re-buncher Cavities for the LIPAC Deuteron Accelerator

impedance, vacuum, linac, beam-transport

184

A. Lara, I. Podadera, F. Toral
CIEMAT, Madrid, Spain

Funding: Work partially supported by Spanish Ministry of Science and Innovation under project ENE2009-11230.
Re-buncher cavities are an essential component of LIPAC (Linear IFMIF Prototype Accelerator), presently being built at Rokkasho (Japan). The deuteron beam exiting from the RFQ (Radio Frequency Quadrupole) structure has to be properly adapted to the superconducting RF (SRF) linac. Re-bunchers are placed in the Medium Energy Beam Transport (MEBT) line and their objective is to longitudinally focus the deuteron beam. IFMIF re-bunchers must provide a 350 kV E0LT at 175 MHz continuous wave (CW). The available length for the re-buncher is limited by the general layout of the MEBT. The high power dissipation derived from the high effective voltage and the short available length is an important design challenge. Four different normal conducting cavity designs were investigated: the pillbox type, double gap coaxial resonators, and multi-gap quarter wave and H resonators. The performance of these cavities was studied with the numerical codes HFSS and ANSYS. The fundamental frequency and field pattern of each re-buncher was investigated in HFSS. This work presents the results of such analyses.

MOPC049

Bead-pull Test Bench for Studying Accelerating Structures at RHUL

rfq, quadrupole, controls, resonance

187

S. Molloy
ESS, Lund, Sweden
R. Ainsworth, G.E. Boorman
Royal Holloway, University of London, Surrey, United Kingdom
C. Gabor
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
A. Garbayo
AVS, Eibar, Gipuzkoa, Spain
A.P. Letchford
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
A. Lyapin
JAI, Egham, Surrey, United Kingdom
P. Savage
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

A bead-pull test stand has been constructed at Royal Holloway, University of London (RHUL) with the ability to provide electric field profile measurements along five degrees of freedom using the perturbation method. In this paper, we present example measurements using the test bench which include a field flatness profile of a 324MHz four vane Radio Frequency Quadrupole (RFQ) model designed as part of the Front End Test Stand (FETS) development at Rutherford Appleton Laboratory (RAL). Mechanical and operational details of the apparatus will also be described, as well as future plans for the development and usage of this facility.

MOPC050

Multipacting Analysis for the Superconducting RF Cavity HOM Couplers in ESS

electron, simulation, HOM, superconducting-RF

190

S. Molloy
ESS, Lund, Sweden
R. Ainsworth
Royal Holloway, University of London, Surrey, United Kingdom
R.J.M.Y. Ruber
Uppsala University, Uppsala, Sweden

The European Spallation Source (ESS) linac will consist of three families superconducting RF cavities to accelerate protons to the required 5 MW for collision with the target. If it is determined that HOM damping is required to limit the effect of beam induced modes, it is quite likely that HOM couplers will be installed. Multipacting in these couplers is a concern as thermally induced detuning of the fundamental notch filter has limited the achievable gradient in other high power machines. It is therefore important to avoid potential multipacting conditions during the design phase. Presented here are simulations using the Track3P code developed at SLAC. Multipacting regions are highlighted, electron trajectories are shown, and suitability of the proposed HOM coupler design is discussed.

MOPC051

The 100 MHz RF System for the MAX IV Storage Rings

LLRF, storage-ring, HOM, impedance

193

Å. Andersson, E. Elafifi, M. Eriksson, D. Kumbaro, P. Lilja, L. Malmgren, R. Nilsson, H. Svensson, P.F. Tavares
MAX-lab, Lund, Sweden
J.H. Hottenbacher
RI Research Instruments GmbH, Bergisch Gladbach, Germany
A. Milan
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
A. Salom
ELETTRA, Basovizza, Italy

The construction of the MAX IV facility has started and user operation is scheduled to commence 2015. The facility is comprised of two storage rings optimized for different wavelength ranges, and a linac-based short pulse facility. In this paper the RF systems for the two storage rings are described. The RF systems will be based on either tetrode or solid state amplifiers working at 100 MHz. Circulators will be used to give isolation between cavity and power amplifier. The main cavities are of normal conducting, entire copper, capacity loaded type, where the present cavities at MAX-lab has served as prototypes. For the MAX IV ring operation it is essential to elongate bunches, in order to minimize the influence of intra beam scattering on beam transverse emittances. For this, 3rd harmonic passive (Landau-) cavities are employed. These are of similar type as the main cavities, mainly because the capacity loaded type has the advantage of pushing higher order modes to relatively high frequencies compared to pill-box cavities. Digital low level RF systems will be used, bearing in mind the possibility of post mortem analysis.

MOPC053

Mechanical Design and Fabrication Studies for SPL Superconducting RF Cavities

niobium, linac, SRF, proton

199

S. Atieh, G. Arnau-Izquierdo, I. Aviles Santillana, O. Capatina, T. Renaglia, T. Tardy, N. Valverde Alonso, W. Weingarten
CERN, Geneva, Switzerland

CERN’s R&D programme on the Superconducting Proton Linac’s (SPL) superconducting radio frequency (SRF) elliptical cavities made from niobium sheets explores new mechanical design and consequently new fabrication methods, where several opportunities for improved optimization were identified. A stainless steel helium vessel is under design rather than a titanium helium vessel using an integrated brazed transition between Nb and the SS helium vessel. Different design and fabrication aspects were proposed and the results are discussed hereafter.

MOPC055

High Power Test of the First PIMS Cavity for Linac4

linac, pick-up, vacuum, klystron

205

F. Gerigk, J.-M. Giguet, P. Ugena Tirado, R. Wegner
CERN, Geneva, Switzerland

The PI-Mode Structure (PIMS) accelerates the Linac4 beam from 100 to 160 MeV. Twelve 7-cell cavities will be installed in the linac, with a gradient of ~4 MV/m and operating at a frequency of 352.2 MHz. A full-power prototype has been constructed at CERN in 2010 and was high- power tested in autumn 2010. Peak power tests at the Linac4 duty cycle and high-average power tests at increased duty cycles were completed successful, so that this prototype will be the first of the 12 cavities to be installed in Linac4. This paper reports on the high-power tests and the conditioning experience.

MOPC056

The Linac4 Power Coupler

linac, coupling, vacuum, simulation

208

F. Gerigk, J.-M. Giguet, E. Montesinos, B. Riffaud, P. Ugena Tirado, R. Wegner
CERN, Geneva, Switzerland

Linac4 employs 3 types of accelerating structures after the RFQ: a Drift Tube Linac (DTL), a Cell-Coupled DTL (CCDTL), and a Pi-Mode Structure (PIMS) to accelerate the beam to 160 MeV. The structures are designed for a peak power of 1 MW per coupler, which consists of two parts: a ceramic window, which separates the cavity vacuum from the air in the wave-guides, and a so-called "coupling T", which couples the RF power through an iris to the cavity. In the frame of the Linac4 R&D both devices have been significantly improved with respect to their commonly used design. On the coupler side, the wave-guide short circuit with its matched length has been replaced by a fixed length λ/4 short circuit. The RF matching is done by a simple piston tuner, which allows a quick matching to different cavity quality factors. In the window part, which usually consists of a ceramic disc and 2 pieces of wave-guides with matching elements, the wave-guide sections could be completely suppressed, so that the window became very compact, lightweight, and much simpler to manufacture. In this paper we present electromagnetic simulations, and tests on first prototypes, which were constructed at CERN.

MOPC058

Upgrade of the 200 MHz RF System in the CERN SPS

emittance, impedance, extraction, acceleration

214

E.N. Shaposhnikova, E. Ciapala, E. Montesinos
CERN, Geneva, Switzerland

The 200 MHz RF system, used in the SPS to accelerate all beams including those for the LHC, has four travelling wave structure cavities of different length. To stabilize the future higher intensity LHC beams in the SPS a larger (than now) controlled longitudinal emittance blow-up and therefore larger bucket and voltage amplitude will be necessary. However less voltage will be available in the existing system (which has a maximum peak RF power of 1 MW per cavity) due to the increased beam loading, in particular in the long cavities. This issue will be critical for beam acceleration but especially for beam transfer into the 400 MHz RF system of the LHC. The proposed solution is to shorten the two long cavities and use the freed sections together with spare sections to make two extra cavities and install two new power plants of 1.3 MW each. After this upgrade, which is a major part of the more general SPS upgrade for high luminosity LHC to be completed during 2017, the performance of the SPS RF system with high intensity beams will be significantly improved and at the same time the total impedance of the system will be reduced.

MOPC059

The Plane Wave Transformer Linac Development at NSRRC

linac, simulation, impedance, electron

217

A. Sadeghipanah, J.-Y. Hwang, W.K. Lau
NSRRC, Hsinchu, Taiwan
T.H. Chang
NTHU, Hsinchu, Taiwan

A Plane-Wave-Transformer (PWT), standing wave linac operating at S-band frequency (2.9979 GHz) is being developed at NSRRC. This structure offers the advantages of high efficiency, compactness, fabrication simplicity and cost. The PWT prototype at NSRRC consists of three cells with two half-cells at the ends, separated by a set of four flat disks suspended and cooled by four water tubes inside a large cylindrical tank. To fully understand its physical properties, numerical modeling of the PWT prototype has been carried out by using the 2-D code SUPERFISH and 3-D code MAFIA. In this paper, we describe the principle properties of this structure, the electric parameters obtained from numerical simulations, and heat dissipation calculation. The mechanical design for prototype linac is also reported.

MOPC061

Simulations to Flatten the Field of the FETS RFQ

rfq, simulation, dipole, quadrupole

223

S.R. Lawrie, A.P. Letchford
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
J.K. Pozimski, P. Savage
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

A high performance Radio Frequency Quadrupole (RFQ) is the next major component to be installed on the Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL) in the UK. The beam dynamics, RF, thermal and mechanical designs of the RFQ are almost complete and so the copper has recently been purchased with a view to start cutting metal near Summer-time. This report summarizes the simulation work performed to ensure the RF design is sound. This includes performance studies of the end-wall dipole suppression fingers, tuning the frequency of the input and output vane end regions and implementing a simple solution to remove modulation induced field tilt.

MOPC062

EMMA RF Comissioning

LLRF, acceleration, controls, beam-loading

226

A.J. Moss, R.K. Buckley, P.A. McIntosh, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

EMMA (Electron Model for Many Applications), the world’s first Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) accelerator is presently in operation at Daresbury Laboratory. The LLRF system is required to synchronize with ALICE (Accelerators and Lasers in Combined Experiments) its injector, which operates at 1.3GHz, and to produce an offset frequency of (+1.5 MHz to -4 MHz) to probe the longitudinal beam dynamics and to also maintain the phase and amplitude of the 19 copper RF cavities of the EMMA machine. The design, commissioning and results of the EMMA RF system is presented.

MOPC068

LANSCE RF System Improvements for Current and Future Programs*

klystron, linac, neutron, proton

238

D. Rees, J.L. Erickson, R.W. Garnett, J.T.M. Lyles, L. Rybarcyk
LANL, Los Alamos, New Mexico, USA

The Los Alamos Neutron Science Center (LANSCE) is in the midst of an upgrade of the RF systems. This project will return LANSCE to its historical operating capability and sustain facility operations into the next decade. The LANSCE accelerator provides pulsed protons and spallation neutrons for defense and civilian applications. This project involves replacing all the existing 201 MHz RF stations and 805 MHz klystrons. LANSCE is also currently in the conceptual design phase of a program called the Material Test Station (MTS) to establish a 1 MW target station to irradiate fast reactor fuels and materials. A pre conceptual design is also in progress to extend the capabilities of MTS to a 2 MW target that will enable the first in a new generation of scientific facilities for the materials community. The emphasis of this new facility is "Matter-Radiation Interactions in Extremes" (MaRIE) which will be used to discover and design the advanced materials needed to meet 21st century national security and energy security challenges. The design and test results of the new RF systems will be presented as well as the RF system changes required to support the new missions.

MOPC072

Design of an RF Feed System for Standing-wave Accelerator Structures

coupling, wakefield, damping, linac

244

J. Neilson, V.A. Dolgashev, S.G. Tantawi
SLAC, Menlo Park, California, USA

Travelling wave (TW) accelerator structures are known to suffer from several deficiencies. A breakdown in one of the cells propagates towards the source. This results in damage to upstream cells in addition to the cell where the breakdown was initiated. The deficiencies of TW accelerator structures can be overcome by using standing wave (SW) cells that are fed in parallel. An RF breakdown is contained to the cell where it originates. This eliminates upstream cell damage and the resulting changes in phase shift between cells. In addition the feed structure can provide a high conductance port for vacuum pumping. We have completed the design of a parallel fed SW structure with a directional coupler for each cell and serpentine waveguide connection between couplers. This design approach improves isolation between the cells resulting in the maximum increase in the operational robustness of the accelerator structure. The design uses four feed arms spaced uniformly around the cell circumference to suppress dipole modes and improve damping of low order wakefields. Construction of a test structure in now underway and is scheduled for testing in October of this year.

MOPC073

A Dual-mode Accelerating Cavity to Test RF Breakdown Dependence on RF Magnetic Fields

simulation, electron, radio-frequency, vacuum

247

A.D. Yeremian, V.A. Dolgashev, J. Neilson, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: * Work Supported by Doe Contract No. DE-AC02-76SF00515
RF Breakdown experiments on short accelerating structures at SLAC have shown that increased rf magnetic fields increase the probability of rf breakdowns. Moreover, the breakdown rate is highly correlated with the peak pulse-heating in soft-copper single-cell standing-wave structures of disk-loaded waveguide type. In these geometries the rf electric and magnetic fields are highly correlated. To separate effects of rf magnetic and electric fields on the rf breakdown rate, we have designed an X-band cavity with a geometry as close to that of a standing-wave accelerator cell as practically possible. This cavity supports two modes: an accelerating TM mode and a TE mode with no-surface-electric field but with a strong magnetic field. The cavity will be constructed and tested at the Accelerator Structure Test Area (ASTA) at SLAC.

MOPC077

Commissioning of Multibunch Feedback Systems at the Fast Ramping Stretcher Ring ELSA

kicker, synchrotron, feedback, booster

250

A. Roth, F. Frommberger, N. Heurich, W. Hillert, M. Schedler, R. Zimmermann
ELSA, Bonn, Germany

Funding: Supported by German Research Foundation through SFB/TR 16 and by Helmholtz Alliance through HA-10¹.
At the Electron Stretcher Facility ELSA of Bonn University, an external beam of either unpolarized or polarized electrons is supplied to hadron physics experiments. The ELSA stretcherring operates in the energy range of 1.2 to 3.5 GeV and achieves a duty cycle of up to 80% using a fast energy ramp of 4 GeV/s. Under these conditions, an increase of the internal beam current from an actual value of 20 mA up to 200 mA is planned. Such an upgrade is mainly limited by the excitation of multibunch instabilities. As one active counteraction, we have installed state-of-the-art bunch-by-bunch feedback systems for the longitudinal, as well as for both transverse planes. The detailed setup with all main components and first results of the commissioning of the systems will be presented. In particular, the performance of the longitudinal feedback with a stabilized synchrotron frequency during the fast energy ramp will be discussed.

MOPC078

Operation of Superconducting Cavities in a Fast Ramping Electron Storage Ring

HOM, impedance, acceleration, storage-ring

253

A. Roth, W. Hillert
ELSA, Bonn, Germany

Funding: Supported by German Research Foundation through SFB/TR 16.
The achievable maximum energy of a medium-sized electron accelerator is mainly limited by the accelerating voltage. Using superconducting (sc) cavities, the energy limitation can be shifted considerably. However, the operation of sc multi-cell cavities in a fast ramping storage ring causes additional problems which were investigated at the 3.5 GeV Electron Stretcher Accelerator ELSA. We studied the use of two 500 MHz sc cavities providing the necessary resonator voltage of up to 14 MV and replacing the normal conducting cavities of PETRA type. A large cavity coupling factor is required, so that using the existing 250 kW klystron, an internal beam of 50 mA can be accelerated up to 5 GeV. In addition, a fast detuning of the resonance frequency of the cavities must be implemented during beam injection and the energy ramp of 4 GeV/s. An appropriate 500 MHz structure is given by a five-cell cavity constructed for the JAERI-FEL-LINAC. Based on this geometry, HOM have been calculated from a numerical simulation. Since all monopole and a larger number of dipole HOM are well above the multibunch instabilities threshold, further studies about beam instabilities damping are essential.

MOPC079

Status of the Low Beta 0.07 Cryomodules for SPIRAL2

cryomodule, LLRF, vacuum, linac

256

P. Bosland, P. Carbonnier, F. Eozénou, P. Galdemard, O. Piquet
CEA/DSM/IRFU, France
M. Anfreville, C. Madec, L. Maurice
CEA/IRFU, Gif-sur-Yvette, France
P.-E. Bernaudin, R. Ferdinand
GANIL, Caen, France
Y. Gomez-Martinez
LPSC, Grenoble Cedex, France
A. Pérolat
CEA, Gif-sur-Yvette, France

The status of the low beta cryomodules for SPIRAL2, supplied by the Irfu institute of CEA Saclay, is reported in this paper. We summarise in three parts the RF tests performed on the cavities in vertical cryostat, the RF power tests of the qualifying cryomodule performed in 2010 and the RF power tests performed in 2011 on the first cryomodule of the series

MOPC080

First Considerations Concerning an Optimized Cavity Design for the Main Linac of BERLinPro

HOM, linac, coupling, impedance

259

B. Riemann, T. Weis
DELTA, Dortmund, Germany
W. Anders, J. Knobloch, A. Neumann
HZB, Berlin, Germany
H.-W. Glock, C. Potratz, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
F. Marhauser
JLAB, Newport News, Virginia, USA

Funding: work supported by BMBF under contracts 05K10PEA and 05K10HRC
The Berlin Energy Recovery Linac Project (BERLinPro) is designed to develop and demonstrate CW linac technology and expertise required to drive next-generation Energy Recovery Linacs. Strongly HOM-damped multicell 1.3 GHz cavities are required for the main linac. The optimization of the cavities presented here is primarily based on the CEBAF 1.5 GHz 5-cell high-current cavity design, including HOM waveguide couplers. The cavity was scaled to 1.3 GHz and extended to 7 cells. Modifications to the end group design have also been studied. An effort was also made to reduce the ratio Epk/Eacc while still permitting HOMs to propagate.

MOPC081

Pulsed Mode Operation and Longitudinal Parameter Measurement of the Rossendorf SRF Gun

gun, SRF, cathode, laser

262

J. Teichert, A. Arnold, H. Büttig, M. Justus, U. Lehnert, P. Michel, P. Murcek, Ch. Schneider, R. Schurig, R. Xiang
HZDR, Dresden, Germany
T. Kamps, J. Rudolph, M. Schenk
HZB, Berlin, Germany
I. Will
MBI, Berlin, Germany

Funding: The European Community-Research Infrastructure Activity under the FP7 program (EuCARD, contract number 227579) the German Federal Ministry of Education and Research grant 05 ES4BR1/8.
The Rossendorf SRF gun with a 3 1/2 cell cavity has been operated since 2007. It has produced CW beam with the electron energy of 3 MeV and the average current up to 16 μA. The electron beam of the gun has successfully injected the ELBE superconducting linac since 2010. The Nb cavity has shown constant quality during the operation and for the Cs2Te photocathode life time of months could be obtained. Recently the gun started to run in the pulsed mode with higher gradient. The longitudinal parameters have been measured in this mode. The dark current arose from the high gradient is studied. The main field emission source has been found to be the half cell. Meanwhile, two modified 3+1/2 cell niobium cavities have been fabricated and tested in Jlab. In this paper the new status of the SRF gun will be presented, and the latest results of the beam experiments will be discussed.

MOPC082

Status of the 325 MHz SC CH-Cavity at IAP Frankfurt

simulation, linac, status, electron

265

M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Amberg, K. Aulenbacher
HIM, Mainz, Germany
W.A. Barth, S. Mickat
GSI, Darmstadt, Germany

Funding: BMBF contract no. 06FY161I
At the Institute for Applied Physics (IAP), University of Frankfurt, a s.c. 325 MHz CH-Cavity is under development for future beam tests at GSI UNILAC, Darmstadt. The cavity with 7 accelerating cells has a geometrical beta of 0.15 corresponding to 11.4 AMeV. The design gradient is 5 MV/m. The geometry of this resonator was optimized with respect to a compact design, low peak fields, surface processing, power coupling and tuning. Furthermore a new tuning system based on bellow tuners inside the resonator will control the frequency during operation. After rf tests in Frankfurt the cavity will be tested with a 10 mA, 11.4 AMeV beam delivered by the GSI UNILAC. In this paper rf simulations, multipacting analysis as well as thermal calculations will be presented.

MOPC083

Structural Mechanics of Superconducting CH Cavities

simulation, controls, linac, resonance

268

M. Amberg, K. Aulenbacher
HIM, Mainz, Germany
W.A. Barth, S. Mickat
GSI, Darmstadt, Germany
M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany

The superconducting CH-structure (Crossbar-H-mode) is a multi-cell drift tube cavity for the low and medium energy range operated in the H21-mode, which has been developed at the Institute for Applied Physics (IAP) of Frankfurt University. With respect to different high power applications two types of superconducting CH-structures (f = 325 MHz, β = 0.16, seven cells and f = 217 MHz, β = 0.059, 15 cells) are presently under construction and accordingly under development. The structural mechanical simulation is a very important aspect of the cavity design. Furthermore, several simulations with ANSYS Workbench have been performed to predict the deformation of the cavity walls due to the cavity cool-down, pressure effects and mechanical vibrations. To readjust the fast frequency changes in consequence of the cavity shape deformation, a new concept for the dynamic frequency tuning has been investigated, including a novel type of bellow-tuner.

MOPC084

The Superconducting cw LINAC Demonstrator for GSI

linac, solenoid, ion, acceleration

271

F.D. Dziuba, M. Busch, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Amberg, K. Aulenbacher
HIM, Mainz, Germany
W.A. Barth, S. Mickat
GSI, Darmstadt, Germany

Funding: BMBF Contr. No. 06FY9089I, Helmholtz Institut Mainz
At GSI a new, superconducting (sc) continuous wave (cw) LINAC is under design in cooperation with the Institute for Applied Physics (IAP) of Frankfurt University and the Helmholtz Institut Mainz (HIM). This proposed LINAC is highly requested by a broad community of future users to fulfill the requirements of nuclear chemistry, nuclear physics, and especially in the research field of Super Heavy Elements (SHE). In this context the preliminary layout of the LINAC has been carried out by IAP. The main acceleration of up to 7.3 AMeV will be provided by nine sc Crossbar-H-mode (CH) cavities operated at 217 MHz. Currently, a prototype of the cw LINAC as a demonstrator is under development. The demonstrator comprises a sc CH-cavity embedded between two sc solenoids mounted in a horizontal cryomodule. A full performance test of the demonstrator in 2013/14 by injecting and accelerating a beam from the GSI High Charge Injector (HLI) is one important milestone of the project. The status of the demonstrator is presented.

MOPC085

Quality Assessment for Industrially Produced High-Gradient Superconducting Cavities

niobium, superconducting-cavity, SRF, linac

274

F. Schlander, S. Aderhold, E. Elsen, D. Reschke, M. Wenskat
DESY, Hamburg, Germany

Funding: This work is supported by the Commission of the European Communities under the 7th Framework Programme “Construction of New Infrastructures – Preparatory Phase”, contract number 206711.
A series of some 600 superconducting 1.3 GHz cavities will start being delivered to DESY by industry in early 2012. Although a considerably smaller gradient satisfies the needs for the European XFEL the electro-polished cavities (50% of the delivery) are deemed to be suitable for gradients in excess of 35 MV/m, the performance goal of the International Linear Collider (ILC). Specifically 24 cavities will be supplied without helium tank to enable further investigations. The results may serve to improve overall performance; limitations such as field emission and thermal breakdown of superconductivity ("quench") are still under investigation. For this matter the DESY ILC group has developed tools to monitor aspects of the cavity fabrication. An automated optical mapping system (OBACHT) is being commissioned and will be complemented by software for automated cavity surface feature recognition. For cold RF tests a Second Sound setup for locating the positions of the thermal breakdown is routinely used. These diagnostic tools will give guidance on post-processing cavities for best performance. The current status of these projects will be described.

MOPC086

Description and First Experience with the RF Measurement Procedure for the European XFEL SC Cavity Production

HOM, SRF, cryomodule, superconducting-cavity

277

A.A. Sulimov, Th. Buettner, A. Gössel, D. Kostin, G. Kreps, W.-D. Möller, D. Reschke, J.H. Thie, K. Twarowski
DESY, Hamburg, Germany

Cavity production for the European XFEL was recently started with first Nb sheets arriving. From this stage to the accelerating module being ready for the linac installation, many critical RF measurements are necessary. During the mechanical cavity fabrication the cavity half-cells, dumb-bells and end-groups are measured and sorted. The cavity spectrum and field profiles are measured and tuned. The HOM (Higher Oder Modes) couplers filter tuning, vertical cavity RF tests, cavity checks during the string assembly and final cavity performance measurements in the module as well as the fundamental mode and HOM RF spectra measurements complete the sequence. We present the procedures of the RF measurements and discuss the first results for the XFEL prototype modules with special attention for the cavity tuning.

Poster MOPC086 [0.515 MB]

MOPC088

Bead-pull Measurement using Phase-Shift Technique in Multi-cell Elliptical Cavity

linac, vacuum, controls, monitoring

280

S. Ghosh, A. Mandal, S. Seth, S.S. Som
DAE/VECC, Calcutta, India

The project on the development of high-beta multi-cell elliptical shape superconducting rf linac cavity at around 704 MHz has been funded at VECC, Kolkata, India. A full-scale copper prototype cavity has been designed and fabricated. There are 5 distinct modes exist in the cavity and the accelerating mode is pi-mode in which each cell operates at same frequency with phase difference of 180 degrees between two neighboring cells. A fully automated bead-pull measurement setup has been developed for analyzing these modes and field profile distribution at different modes in such type of linac cavity. A special measurement method inside the cavity using phase-shift technique is proposed in this paper, which describes the development of mechanical setup comprising pulleys and stepper motor–gear arrangement, PC-based control system for precise movement of bead using stepper motor, measurement using VNA, development of software for data acquisition & automation and measurement results for the 5-cell copper prototype cavity.

MOPC089

RF Simulations for the QWR Cavities of PIAVE-ALPI

simulation, ion, linac, beam-losses

283

M. Comunian, F. Grespan, A. Palmieri
INFN/LNL, Legnaro (PD), Italy

The PIAVE-ALPI linac is composed of several families of QWR cavities. In order to have a thorough description of the accelerator in terms of beam dynamics, a detailed field mapping of the accelerating cavities is necessary, including non-linear behavior of the off-axis fields, as well as the steering and dispersion effects due to transverse components. For such a purpose, a set of RF simulation was accomplished, with the codes HFSS and COMSOL. The details about these simulations and the main outcomes and results will be described in this article.

MOPC090

Tuner Performance in the S1-global Cryomodule

controls, cryomodule, high-voltage, coupling

286

R. Paparella, A. Bosotti, C. Pagani
INFN/LASA, Segrate (MI), Italy
C. Albrecht, K. Jensch, L. Lilje
DESY, Hamburg, Germany
S. Barbanotti, Y.M. Pischalnikov, W. Schappert
Fermilab, Batavia, USA
H. Hayano, E. Kako, S. Noguchi, N. Ohuchi, Y. Yamamoto
KEK, Ibaraki, Japan

S1-Global is a collaborative effort of INFN, DESY, FNAL, SLAC and KEK, in the framework of the ILC global collaboration. For this project two cryomodules, 6 meter long and hosting four SC cavities each, were realized and successfully cold tested at KEK-STF. Three different cavity tuning systems, provided with fast tuning capability through piezoelectric actuators (piezo), were installed, and fully characterized in static and dynamic operation: Blade Tuner from INFN/FNAL, Saclay Tuner from DESY, Slide Jack Tuner from KEK. Finally, Lorenz Force Detuning (LFD) active compensation has been successfully achieved during high power cavity tests in pulsed RF regime, where active control of the LFD disturbance up to Hz-level residual detuning has been achieved with each type of tuning system up to the maximum gradient of each cavity. The installation procedures, together with the relevant results and their analyses are summarized in the paper.

MOPC091

Status of the XFEL 3.9 GHz Injector Section

cryogenics, cryomodule, linac, status

289

P. Pierini, M. Bonezzi, A. Bosotti, M. Fusetti, P.M. Michelato, L. Monaco, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
E. Vogel
DESY, Hamburg, Germany

The European XFEL will use a superconducting third harmonic section to achieve the necessary beam quality for the FEL process. The concept has been successfully proven at the FLASH linac in DESY, with a 4 cavity superconducting module contributed by FNAL. The design of the third harmonic system at the XFEL injector is being finalized and prototypes of the components (cavities and couplers) have been fabricated and are currently in the testing stage. The paper will provide a status of the activities.

MOPC092

Effect of Current Densities on Sulfur Generation at Electropolished Niobium Surface

niobium, cathode, electron, vacuum

292

P.V. Tyagi
Sokendai, Ibaraki, Japan
H. Hayano, S. Kato, M. Nishiwaki, T. Noguchi, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan

We conducted a series of electropolishing (EP) experiments in aged EP acid with high (≈50 mA/cm²) and low (≈30 mA/cm²) current densities on Nb surfaces. The experiments were carried out both for laboratory coupons and a real Nb single cell cavity with six witness samples located at three typical positions (equator, iris and beam pipe). All the samples surface were investigated by XPS (x-ray photoelectron spectroscopy), SEM (scanning electron microscope) and EDX (energy dispersive x-ray spectroscopy). The surface analysis showed the EP with a high current density produced a huge amount sulfate particles at Nb surface whereas the EP with a low current density is very helpful to mitigate sulfate at Nb surface in both the experiments.

MOPC093

Novel Field Emission Scanner for Surface Study of Niobium SRF Cavity

SRF, electron, site, controls

295

S. Kato, M. Nishiwaki, T. Noguchi
KEK, Ibaraki, Japan
V. Chouhan
GUAS, Kanagawa, Japan
P.V. Tyagi
Sokendai, Ibaraki, Japan

It is mandatory to investigate field emission on Nb SRF cavity systematically since strong field emission often limits the cavity performance. The field emission strength and the number of emission sites strongly depend on Nb surface properties which are determined by its surface treatment and handling. Field emission scanner (FES) developed allows us to measure a distribution of the field emitting sites over a sample surface at a given field strength along with its FE-SEM observation and energy dispersive x-ray analysis. FES consists of an anode needle driven by precise 3D stepping motors and an eucentric sample stage. The compact scanner was installed into the space between the object lens and the SEM sample holder. In addition, this system was newly equipped with a sample load-lock system for existing UHV suitcases. Therefore a sample coupon to be observed is hardly exposed to contaminants and dust particles during the transportation. In-situ heating of a sample coupon can be done during an experiment to simulate a baking process of a SRF cavity. This article describes development of the field emission scanner and its preliminary results of the application to niobium samples.

MOPC095

Superconducting Cavity R&D for ILC at MHI

HOM, superconducting-cavity, linac, status

298

H. Hitomi, H. Hara, F. Inoue, K. Kanaoka, K. Sennyu, T. Yanagisawa
MHI, Kobe, Japan

We have developed and manufactured some superconducting RF cavity for STF project in KEK. In recent vertical test in KEK, the MHI-#12 cavity which is one of cavities for STF phase 2 project reached ILC specification(max Eacc was about 40MV/m). So techniques for manufacturing cavity is making steady progress in MHI. To be realized ILC project, we also try to decrease the manufacturing cost by using some new techniques, for example Laser Beam Welding, deep drawing, seamless dumbbell, etc. In this meeting, we will report recent MHI's activities for ILC.

MOPC096

Design and Fabrication of a 5-Cell High Current Superconducting Cavity

HOM, simulation, dipole, quadrupole

301

Y.M. Li, K.X. Liu, S.W. Quan, F. Zhu
PKU/IHIP, Beijing, People's Republic of China
R. Nassiri
ANL, Argonne, USA

Funding: National High Technology Research and Development program 863 (2009AA03Z206)
Energy recovery linacs (ERL) is promising to achieve high average current with superior beam quality. The key component for accelerating such high current beams is the superconducting radio frequency (SRF) cavity. The design of a 1.3 GHz 5-cell high current superconducting cavity has been carried out under the cooperation between Peking University (PKU) and Argonne National Laboratory (ANL). RF properties, damping of the HOMs, multipacting and mechanical features of this cavity have been discussed and the final design is presented.

MOPC097

LLRF Control System for PKU DC-SC Photocathode Injector

controls, LLRF, superconducting-cavity, SRF

304

H. Zhang, Y.M. Li, K.X. Liu, F. Wang, B.C. Zhang
PKU/IHIP, Beijing, People's Republic of China

A 1.3 GHz 3.5 Cell LG niobium cavity is installed for the new PKU DC-SC injector as its accelerating cavity with working temperature is 2K. High amplitude and phase stability is required for the updated SRF photocathode injector. This paper describes the design of Low Level RF control system based on FPGA, including hardware and software,and the communication function is realized by Tri-State Ethernet. The system should be operated on the precision with the amplitude of ±0.1% and phase stability of ±0.1°.

MOPC101

Vertical Test of PEFP Prototype SRF Cavity

accelerating-gradient, electron, linac, SRF

307

H.S. Kim, Y.-S. Cho, H.-J. Kwon
KAERI, Daejon, Republic of Korea

Funding: This work was supported by Ministry of Education, Science and Technology of the Korean Government.
The PEFP Proton linac is a 100-MeV machine which consists of a proton injector, a 3-MeVRFQ and 100-MeV DTL. For the extension of the machine beyond 100 MeV, SRF technology is under consideration. As a prototyping activity, a superconducting RF cavity with a geometrical beta of 0.42 and a resonant frequency of 700 MHz has been designed, fabricated and tested. The cavity is an elliptical shape with 5 cells stiffened by double-ring structure. A design accelerating gradient is 8.0 MV/m at the operating temperature of 4.2 K and maximum duty factor is 9%. For the vertical test of the cavity, a cryostat with a vacuum jacket and multi-layer insulation was prepared. The RF system for driving the cavity is based on PLL to track the resonant frequency. In case of lack of RF power, a two-way RF power combiner based on splitted coaxial transmission line is considered. The details of the vertical test setup and test results will be presented in this paper.

MOPC102

RF and Surface Properties of Superconducting Samples

niobium, quadrupole, superconductivity, superconducting-cavity

310

T. Junginger, W. Weingarten
CERN, Geneva, Switzerland
T. Junginger
MPI-K, Heidelberg, Germany
R. Seviour
Lancaster University, Lancaster, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Work supported by the German Doctoral Students program of the Federal Ministry of Education and Research (BMBF)
The surface resistance Rs of superconducting cavities can be obtained from the unloaded quality factor Q0. Since Rs varies strongly over the cavity surface its value must be interpreted as averaged over the whole cavity surface. A more convenient way to investigate the surface resistance of superconducting materials is therefore to examine small samples, because they can be manufactured cheaply, duplicated easily and used for further surface analyses. At CERN a compact Quadrupole Resonator has been developed for the RF characterization of superconducting samples at different frequencies. In this contribution, results from measurements on bulk niobium and niobium film on copper samples are presented. It is shown how different contributions to the surface resistance depend on temperature, applied RF magnetic field and frequency. Furthermore, measurements of the maximum RF magnetic field as a function of temperature and frequency in pulsed and CW operation are presented. The study is accompanied by measurements of the surface properties of the samples by various techniques.

MOPC103

Cryostat for Testing HIE-ISOLDE Superconducting RF Cavities

vacuum, cryomodule, cryogenics, niobium

313

O. Capatina, J.P. Brachet, G. Cuccuru, M. Pasini, T. Renaglia, M. Therasse, B. Vullierme
CERN, Geneva, Switzerland

The High Intensity and Energy ISOLDE (HIE-ISOLDE) project is a major upgrade of the existing ISOLDE and REX-ISOLDE facilities at CERN [1], with the objective of increasing the energy and the intensity of the delivered radioactive ion beams (RIB). This project aims to fill the request for a more energetic post accelerated beam by means of a new superconducting (SC) linac based on Quarter Wave Resonators (QWRs). A research and development program looking at all different aspects of the SC linac has started in 2008 and continued throughout 2010. In particular the R&D effort has focused on the development of the high β cavity (β = 10.3%), for which it has been decided to adopt the Nb sputtered on Cu substrate technology. Two prototype cavities were manufactured and are undergoing RF cold tests. The pre-series cavity fabrication is under way using 3D forged Cu billets. A single vacuum cryostat was designed and built to test these cavities at liquid helium temperatures. The paper details the main design concepts of the test cryostat as well as the results of the cryogenic behavior of the complete set-up including the cryostat, the RF cavity, the tuner and the main coupler.

MOPC104

HIE-ISOLDE SRF Development Activities at CERN

cathode, vacuum, niobium, SRF

316

M. Therasse, O. Brunner, S. Calatroni, J.K. Chambrillon, B. Delaup, M. Pasini
CERN, Geneva, Switzerland

The HIE-ISOLDE project has initiated a new development phase on the SRF domain at CERN. In particular, the HIE-ISOLDE project aims at the construction of the 32 Quarter Wave Resonators (QWRs) using the Nb on Cu sputtering technology. The paper describes the refurbishment of the test infrastructure and the activities from the cavity production to the cold test, including quality assurance procedure for the correct handling of the resonators.

MOPC105

Design of the High Beta Cryomodule for the HIE-ISOLDE Upgrade at CERN

vacuum, alignment, cryomodule, target

319

L.R. Williams, A.P. Bouzoud, N. Delruelle, J. Gayde, Y. Leclercq, M. Pasini, J.Ph. G. L. Tock, G. Vandoni
CERN, Geneva, Switzerland

The major upgrade of the energy and intensity of the radioactive ion beams of the existing ISOLDE and REX-ISOLDE facilities at CERN will, in the long term, require downstream of the existing machine, the installation of four high-β and two low-β cryo-modules. The first stage of this upgrade, involving the design, construction, installation and commissioning of two high-β cryo-modules is approved and design work is underway at CERN. The high-β cryo-module houses five high-β superconducting cavities and one superconducting solenoid. As well as providing optimum conditions for physics, where the internal active components must remain aligned within tight tolerances, the cryo-modules need to function under stringent common vacuum and cryogenic conditions. To preserve the RF cavity performance their assembly and sub-system testing will need to be carried out using specifically designed tooling in a class 100 clean-room. We present the determining factors constraining the design of the high-β cryo-module together with the design choices that these factors have imposed.

MOPC106

Study of the Variation of Transverse Voltage in the 4 Rod Crab Cavity for LHC

luminosity, simulation, HOM, dipole

322

B.D.S. Hall, P.K. Ambattu, G. Burt, C. Lingwood
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
P. Goudket, C. Hill
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The planned high luminosity upgrade to LHC will utilise crab cavities to rotate the beam in order to increase the luminosity in the presence of a finite crossing angle. A compact design is required in order for the cavities to fit between opposing beam-lines. In this paper we discuss we discuss one option for the LHC crab cavity based on a 4 rod TEM deflecting cavity. Due to the large transverse size of the LHC beam the cavity is required to have a large aperture while maintaining a constant transverse voltage across the aperture. The cavity has been optimised to minimise the variation of the transverse voltage while keeping the peak surface electric and magnetic fields low for a given kick. This is achieved while fitting within the strict design space of the LHC. The variation of deflecting voltage across the aperture has been studied numerically and compared with numerical and analytical estimates of other deflecting cavity types. Performance measurements an aluminium prototype of this cavity are presented and compared to the simulated design.

MOPC107

HOM and FP Coupler Design for the NLSF High Gradient SC Cavity

HOM, simulation, SRF, damping

325

R.M. Jones, N. Juntong
UMAN, Manchester, United Kingdom

The design of both higher order mode (HOM) and fundamental power (FP) couplers for the New Low Surface Field (NLSF) cavity* is presented. Here we study using the ILC baseline couplers for this new superconducting cavity. A Balleyguier method** of calculating external quality factor is used and the results validated using both Microwave studio and HFSS.
* N. Juntong and R.M. Jones, SRF2009, THPPO024, 2009.
** P. Balleyguier, LINAC98, MO4037, 1998

MOPC108

Cornell SRF New Materials Program*

niobium, SRF, controls, monitoring

328

S. Posen, M. Liepe, Y. Xie
CLASSE, Ithaca, New York, USA

Funding: Work supported by NSF Career award PHY-0841213, DOE award ER41628, and the Alfred P. Sloan Foundation
The SRF group at Cornell has recently pioneered an extensive program to investigate alternative materials for superconducting cavities. We have developed facilities to fabricate Nb3Sn, a superconductor which will theoretically be able to reach more than twice the maximum accelerating field of Nb in a cavity under the same operating conditions. In addition, with the critical temperature of Nb3Sn being twice that of Nb, Nb3Sn would allow operation of SRF cavities with a much higher cryogenic efficiency. We have also manufactured two TE cavities that measure the RF properties of small, flat samples, ideal for material fabrication methods in development. This paper presents an overview of the materials research program. First results from tests of Nb3Sn samples are presented.

MOPC109

Suppression of Coupler Kicks in 7-Cell Main Linac Cavities for Cornell's ERL

linac, emittance, resonance, simulation

331

N.R.A. Valles, M. Liepe, V.D. Shemelin
CLASSE, Ithaca, New York, USA

Funding: Supported by NSF award DMR-0807731
Cornell is developing a 5 GeV Energy Recovery Linac operating at 100 mA with very small emittances (~30 pm at 77 pC bunch charge) in the horizontal and vertical directions. We investigate the effect of the fundamental RF power couplers of the main linac SRF cavities on the beam using the ACE3P software package. The cavities in the ERL main linac will be operated at very high loaded quality factors of up to 6.5·10⁷, corresponding to a full bandwidth of only 20 Hz. Cavity microphonics will detune the cavities by more than one bandwidth during operation, thereby causing a time dependent change of the coupler kick in addition to its fast oscillation at the RF frequency. In order to investigate the dependence of the coupler kick on the cavity frequency, we calculate the coupler kick given to the beam for the case of a detuned RF cavity. We show that a compensation stub geometry located opposite to the input coupler port can be optimized to reduce the overall kick given to the beam and the emittace growth caused by its time dependence.

MOPC111

Progress of ILC High Gradient SRF Cavity R&D at Jefferson Lab

SRF, niobium, accelerating-gradient, cryogenics

334

R.L. Geng, J. Dai, G.V. Eremeev, A.D. Palczewski
JLAB, Newport News, Virginia, USA

Funding: US Department of Energy
Latest progress of ILC high gradient SRF cavity R&D at Jefferson Lab will be presented. 9 out of 10 real 9-cell cavities reached an accelerating gradient of more than 38 MV/m at a unloaded quality factor of more than 8·10⁹. New understandings of quench limitation in 9-cell cavities are obtained through instrumented studies of cavities at cryogenic temperatures. Our data have shown that present limit reached in 9-cell cavities is predominantly due to localized defects, suggesting that the fundamental material limit of niobium is not yet reached in 9-cell cavities and further gradient improvement is still possible. Some examples of quench-causing defects will be given. Possible solutions to pushing toward the fundamental limit will be described.

MOPC112

Fabrication and Testing Status of CEBAF 12 GeV Upgrade Cavities

cryomodule, HOM, electron, status

337

F. Marhauser, A. Burrill, G.K. Davis, D. Forehand, C. Grenoble, J. Hogan, R.B. Overton, A.V. Reilly, R.A. Rimmer, M. Stirbet
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The 12 GeV upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory (JLab) is under way. All cavities have been built by industry and are presently undergoing post-processing and final low and high power qualification before cryomodule assembly. The status is reported including fabrication-related experiences, observations and issues throughout production, post-processing and qualification.

MOPC113

Results of Cavity Series Fabrication at Jefferson Laboratory for the Cryomodule “R100”

cryomodule, HOM, target, damping

340

F. Marhauser, W.A. Clemens, M.A. Drury, D. Forehand, J. Henry, S. Manning, R.B. Overton, R.S. Williams
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A series production of eight superconducting RF cavities for the cryomodule R100 was conducted at JLab in 2010. The cavities underwent chemical post-processing prior to vertical high power testing and routinely exceeded the envisaged performance specifications. After cryomodule assembly, cavities were successfully high power acceptance tested. In this paper, we present the achievements paving the way for the first demonstration of 100 MV (and beyond) in a single cryomodule to be operated at CEBAF.

MOPC114

Design, Fabrication and Testing of Medium-Beta 650 MHz SRF Cavity Prototypes for Project-X

SRF, linac, electron, vacuum

343

F. Marhauser, W.A. Clemens, J. Henry, P. Kneisel, R. Martin, R.A. Rimmer, G. Slack, L. Turlington, R.S. Williams
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A new type of superconducting radio frequency (SRF) cavity shape with a shallow equator dome to reduce electron impact energies for suppressing multipacting barriers has been proposed. The shape is in consideration for the first time in the framework of Project-X to design a potential multi-cell cavity candidate for the medium-beta section of the SRF proton CW linac operating at 650 MHz. Rationales covering the design of the multi-cell cavity, the manufacture, post-processing and high power testing of two single-cell prototypes are presented.

MOPC115

JLab SRF Cavity Fabrication Errors, Consequences and Lessons Learned

cryomodule, target, SRF, niobium

346

F. Marhauser
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
Today, elliptical superconducting RF (SRF) cavities are preferably made from deep-drawn niobium sheets as pursued at Jefferson Laboratory (JLab). The fabrication of a cavity incorporates various cavity cell machining, trimming and electron beam welding (EBW) steps as well as surface chemistry that add to forming errors creating geometrical deviations of the cavity shape from its design. An analysis of in-house built cavities over the last years revealed significant errors in cavity production. Past fabrication flaws are described and lessons learned applied successfully to the most recent in-house series production of multi-cell cavities.

MOPC116

Development of Nb and Alternative Material Thin Films Tailored for SRF Applications

SRF, ECR, ion, electron

349

A-M. Valente-Feliciano, H.L. Phillips, C.E. Reece, J.K. Spradlin, B. Xiao, X. Zhao
JLAB, Newport News, Virginia, USA
H. Baumgart, D. Gu
ODU, Norfolk, Virginia, USA
D. Beringer, R.A. Lukaszew
The College of William and Mary, Williamsburg, USA
K.I. Seo
NSU, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S.DOE Contract No. DE-AC05-06OR23177.
Over the years, Nb/Cu technology, despite its shortcomings due to the commonly used magnetron sputtering, has positioned itself as an alternative route for the future of superconducting structures used in accelerators. Recently, significant progress has been made in the development of energetic vacuum deposition techniques, showing promise for the production of thin films tailored for SRF applications. JLab is pursuing energetic condensation deposition via techniques such as Electron Cyclotron Resonance and High Power Impulse Magnetron Sputtering. As part of this project, the influence of the deposition energy on the material and RF properties of the Nb thin film is investigated with the characterization of their surface, structure, superconducting properties and RF response. It has been shown that the film RRR can be tuned from single digits to values greater than 400. This paper presents results on surface impedance measurements correlated with surface and material characterization for Nb films produced on various substrates, monocrystalline and polycrystalline as well as amorphous. A progress report on work on NbTiN and AlN based multilayer structures will also be presented.

MOPC117

Advance in Vertical Buffered Electropolishing on Niobium for Particle Accelerators*

SRF, cathode, niobium, radio-frequency

352

A.T. Wu, S. Jin, J.D. Mammosser, C.E. Reece, R.A. Rimmer
JLAB, Newport News, Virginia, USA
L. Lin, X.Y. Lu, K. Zhao
PKU/IHIP, Beijing, People's Republic of China

Funding: The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.
Niobium (Nb) is the most popular material that has been employed for making superconducting radio frequency (SRF) cavities to be used in various particle accelerators over the last couple of decades. One of the most important steps in fabricating Nb SRF cavities is the final chemical removal of 150 μm of Nb from the inner surfaces of the SRF cavities. This is usually done by either buffered chemical polishing (BCP) or electropolishing (EP). Recently a new Nb surface treatment technique called buffered electropolishing (BEP) has been developed at Jefferson Lab. It has been demonstrated that BEP can produce the smoothest surface finish on Nb ever reported in the literature while realizing a Nb removal rate as high as 10 μm/min that is more than 25 and 5 times quicker than those of EP and BCP(112) respectively. In this contribution, recent advance in optimizing and understanding BEP treatment technique is reviewed. Latest results from RF measurements on BEP treated Nb single cell cavities by our unique vertical polishing system will be reported.
Authored by The Southeastern Universities Research Association, Inc. under U.S. DOE Contract No. DE-AC05-84ER40150.

MOPC118

Effects of the Thickness of Niobium Surface Oxide Layers on Field Emission*

controls, SRF, niobium, HOM

355

A.T. Wu, S. Jin, J.D. Mammosser, R.A. Rimmer
JLAB, Newport News, Virginia, USA
X.Y. Lu, K. Zhao
PKU/IHIP, Beijing, People's Republic of China

Funding: The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.
Field emission on the inner surfaces of niobium superconducting radio frequency cavities is still one of the major obstacles for reaching high accelerating gradients for SRF community. Our previous experimental results* seemed to imply that the threshold of field emission was related to the thickness of Nb surface oxide layers. In this contribution, a more detailed study on the influences of the surface oxide layers on the field emission on Nb surfaces will be reported. By anodization technique, the thickness of the surface pentoxide layer was artificially fabricated from 3 nm up to 460 nm. A home-made scanning field emission microscope was employed to perform the scans on the surfaces. Emitters were characterized using a scanning electron microscope together with an energy dispersive x-ray analyzer. The SFEM experimental results were analyzed in terms of surface morphology and oxide thickness of Nb samples and chemical composition and geographic shape of the emitters. A model based on the classic electromagnetic theory was developed trying to understand the experimental results. Possibly implications for Nb SRF cavity applications from this study will be discussed.
* A.T. Wu et al., Proc. of IPAC 2010, Kyoto, Japan, WEPEC081, p. 3067 (2010).
Authored by The Southeastern Universities Research Association, Inc. under U.S. DOE Contract No. DE-AC05-84ER40150.

MOPC119

Fastest Electropolishing Technique on Niobium for Particle Accelerators*

SRF, cathode, niobium, linear-collider

358

A.T. Wu, S. Jin, R.A. Rimmer
JLAB, Newport News, Virginia, USA
X.Y. Lu, K. Zhao
PKU/IHIP, Beijing, People's Republic of China

Funding: The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.
Field emission on the inner surfaces of niobium (Nb) superconducting radio frequency (SRF) cavities is still one of the major obstacles for reaching high accelerating gradients for SRF community. Our previous experimental results [1] seemed to imply that the threshold of field emission was related to the thickness of Nb surface oxide layers. In this contribution, a more detailed study on the influences of the surface oxide layers on the field emission on Nb surfaces will be reported. By anodization technique, the thickness of the surface pentoxide layer was artificially fabricated from 3nm up to 460nm. A home-made scanning field emission microscope (SFEM) was employed to perform the scans on the surfaces. Emitters were characterized using a scanning electron microscope together with an energy dispersive x-ray analyzer. The experimental results could be understood by a simple model calculation based on classic electromagnetic theory as shown in Ref.1. Possibly implications for Nb SRF cavity applications from this study will be discussed.
Authored by The Southeastern Universities Research Association, Inc. under U.S. DOE Contract No. DE-AC05-84ER40150.

MOPC120

Design of Superconducting Parallel-bar Deflecting/Crabbing Cavities

coupling, luminosity, SRF, proton

361

J.R. Delayen, S.U. De Silva
ODU, Norfolk, Virginia, USA

The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. We present an analysis of several designs of parallel-bar cavities and their electromagnetic properties.

MOPC121

Design of Low-frequency Superconducting Spoke Cavities for High-velocity Applications

impedance, HOM, superconductivity, linac

364

J.R. Delayen, C.S. Hopper
ODU, Norfolk, Virginia, USA
R.G. Olave
Old Dominion University, Norfolk, Virginia, USA

Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β~0.15 to β~0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of 325 and 352 MHz spoke cavities optimized for β=0.8 and β=1.

MOPC122

Etching of Niobium Sample Placed on Superconducting Radio Frequency Cavity Surface in Ar/CL2 Plasma

plasma, SRF, niobium, diagnostics

367

J. Upadhyay, M. Nikolić, S. Popović, L. Vušković
ODU, Norfolk, Virginia, USA
H.L. Phillips, A-M. Valente-Feliciano
JLAB, Newport News, Virginia, USA

Plasma based surface modification is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. It has been proven with flat samples that the bulk Niobium (Nb) removal rate and the surface roughness after the plasma etchings are equal to or better than wet etching processes. To optimize the plasma parameters, we are using a single cell cavity with 20 sample holders symmetrically distributed over the cell. These holders serve the purpose of diagnostic ports for the measurement of the plasma parameters and for the holding of the Nb sample to be etched. The plasma properties at RF (100 MHz) and MW (2.45 GHz) frequencies are being measured with the help of electrical and optical probes at different pressures and RF power levels inside of this cavity. The niobium coupons placed on several holders around the cell are being etched simultaneously. The etching results will be presented at this conference.

MOPC123

Temperature Dependent Microphonics in the BNL Electron Cooler*

resonance, electron, linac, cryogenics

370

P. Jain
Stony Brook University, Stony Brook, USA
I. Ben-Zvi, C. Schultheiss
BNL, Upton, Long Island, New York, USA

An R&D Energy Recovery Linac (ERL), to be used in the BNL electron cooler, has been operational in a developmental setting. The ERL requires a cryogenic system to supply cooling to a superconducting RF gun and the 5-cell superconducting RF cavity system that is kept cold at 2K. The 2K superfluid bath is produced by pumping on the bath using a sub-atmospheric warm compression system. During a test run in October 2010, a resonance peak corresponding to a noise of 30 Hz was observed at 1.88K. This noise peak, present at all temperatures below 2K, is assumed to be of mechanical origin from the vibration of the cryopump. Another resonance noise peak of 16 Hz, characteristic of the system, was observed at 1.98K, which shifted towards the 30 Hz peak as the temperature of the cryostat varied from 1.98K to 1.88K. The 16 Hz resonance peak upon hitting the 30 Hz resonance peak, sets a resonance condition, thereby the 30 Hz peak getting amplified by more than five times. In this paper we explore the origin of the temperature dependent 16 Hz resonance peak and give a physical explanation of the resonance.

MOPC126

High Power RF System for TRIUMF E-Linac Injector

klystron, TRIUMF, linac, cryomodule

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

storage-ring, power-supply, booster, klystron

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

klystron, linac, rf-amplifier, superconducting-cavity

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

linac, impedance, vacuum, klystron

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)

booster, rf-amplifier, storage-ring, simulation

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.

MOPC134

Multifrequency High Power Microwave Electric-vacuum Devices

electron, klystron, vacuum, acceleration

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

controls, power-supply, linac, LLRF

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

klystron, linac, neutron, LLRF

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

controls, linac, rf-amplifier, shielding

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

klystron, linac, controls, electron

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

controls, resonance, shielding, SRF

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.

MOPC143

A Reduced Gradient Output Design for SLAC's XL4 X-Band Klystron

simulation, klystron, impedance, beam-loading

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.

MOPC145

Recent Progress on the Technical Realization of the Bunch Phase Timing System BuTiS

controls, laser, diagnostics, status

418

B. Zipfel, P. Moritz
GSI, Darmstadt, Germany

A high precision phase synchronous clock distribution system is mandatory for generating local RF reference signals in an accelerator complex. The dedicated Bunch Timing System (BuTiS) at GSI performs this function. The accuracy of the realized installation under rough ambient conditions is presented. Procedures for calibration and standardization aspects of system modules are pointed out. Hardware as well as software interfaces of the system are described. The interfacing between GPS and BuTiS are explained.

MOPC151

Design and Commissioning of a Multi-frequency Digital Low Level RF Control System*

controls, low-level-rf, linac, superconducting-cavity

433

M. Konrad, U. Bonnes, C. Burandt, J. Conrad, R. Eichhorn, J. Enders, P.N. Nonn, N. Pietralla
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG through CRC 634 and by the BMBF under 06 DA 9024 I.
Triggered by the need to control the superconducting cavities of the S-DALINAC, which have a high loaded quality factor and are thus very susceptible to microphonics, the development of a digital low level RF control system was started. The chosen design proved to be very flexible since other frequencies than the original 3 GHz may be adapted easily: The system converts the RF signal coming from the cavity (e. g. 3 GHz) down to the base band using a hardware I/Q demodulator. The base band signals are digitized by ADCs and fed into a FPGA where the control algorithm is implemented. The resulting signals are I/Q modulated before they are sent back to the cavity. The superconducting cavities are operated with a self-excited loop algorithm whereas a generator-driven algorithm is used for the low Q normal-conducting bunching cavities. A 6 GHz RF front end allows the synchronous operation of a new 2f buncher at the S-DALINAC. Meanwhile, a 325 MHz version has been built to control a pulsed prototype test stand for the p-LINAC at FAIR. We will present the architecture of the RF control system as well as results obtained during operation.

MOPC152

Digital Control System for Solid State Direct Drive™ RF-Linacs

controls, LLRF, linac, pick-up

436

J. Sirtl, M. Back, T. Kluge
Siemens AG, Erlangen, Germany
H. Schröder
ASTRUM IT GmbH, Erlangen, Germany

The Solid State Direct Drive™ concept for RF linacs has previously been introduced*. Due to the different methodology (i.e. solid state based rather than electron tube based) as compared with conventional RF sources a new control system is required to deliver the required LLRF. To support this new technology a fully digital control system for this new concept has been developed. Progresses in Digital – Analogue Converter technology and FPGA technology allows us to create a digital System which works in the 150 Mhz baseband. The complete functionality was implemented in a Virtex 6 FPGA. Dispensing with the PLL allows an excellent jitter-behaviour. For this job, we use three 12 bit ADCs with a Sampling Rate of 1 GS/s and two 16 bit DACs (1 GS/s). The amplitude of the RF source is controlled by dividing the RF modules mounted on the power combiner** into two groups and controlling the relative phase of each group (in effect mimicking an “out-phasing” amplifier). This allows the modules to be operated at their optimum working point and allows a linear amplitude behaviour.
* O. Heid, T. Hughes, Proc. of IPAC10, THPD002, p. 4278, Kyoto, Japan (2010).
** O. Heid, T. Hughes, Proc. of LINAC10, THPD068, Tsukuba, Japan.

MOPC153

Design and Implementation of Automatic Cavity Resonance Frequency Measurement and Tuning Procedure for FLASH and European XFEL Cryogenic Modules

controls, klystron, LLRF, resonance

439

V. Ayvazyan, W. Koprek, D. Kostin, G. Kreps
DESY, Hamburg, Germany
Z. Geng
SLAC, Menlo Park, California, USA

The superconducting cavities in FLASH and European XFEL should be tuned to the frequency of 1.3 GHz after cool down and adjusted to initial frequency before warm up by stepper motor tuners. The initial frequency is 300 kHz far from the operating frequency (1.3 GHz) to remove mechanical hysteresis of the tuner. The cavities should be relaxed to initial frequency to avoid a plastically deformation. In framework of digital low level RF and DOOCS control systems we have developed a simple automatic procedure for the remote resonance frequency measurement and simultaneous remote tuning for all cavities which are driven from the single klystron. The basic idea is based on frequency sweeping both for driving klystron and for generation of local oscillator frequency with constant RF frequency from master oscillator. The developed system has been used during FLASH commissioning in spring 2010 and is in use for cavity and cryogenic module test stands for European XFEL at DESY.

MOPC154

RF Photo Gun Stability Measurement at PITZ

gun, laser, feedback, electron

442

I.I. Isaev, H.-J. Grabosch, M. Gross, L. Hakobyan, Ye. Ivanisenko, G. Klemz, W. Köhler, M. Krasilnikov, M. Mahgoub, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, S. Rimjaem, F. Stephan, G. Vashchenko, S. Weidinger, R.W. Wenndorff
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
M. Hoffmann, H. Schlarb
DESY, Hamburg, Germany
M.A. Khojoyan
YerPhI, Yerevan, Armenia
D. Richter
HZB, Berlin, Germany
A. Shapovalov
NRNU MEPHI, Moscow, Russia
I.H. Templin, I. Will
MBI, Berlin, Germany

The stability of the RF phase in the RF photo injector gun is one of the most important factors for the successful operation of linac based free-electron lasers. Instabilities in the RF launch phase can significantly reduce the beam quality. Investigation on the dependence of different gun parameters and selection of optimal conditions are required to achieve high RF gun phase stability. The phase stability of the RF field is measured using the phase scan technique. Measurements were performed for different operating conditions at the Photo Injector Test facility at DESY, location Zeuthen (PITZ). Obtained stability measurement results will be presented and discussed.

MOPC155

Performance of the Micro-TCA Digital Feedback Board for DRFS Test at KEK-STF

controls, feedback, klystron, LLRF

445

T. Miura, D.A. Arakawa, S. Fukuda, E. Kako, H. Katagiri, T. Matsumoto, S. Michizono, Y. Yano
KEK, Ibaraki, Japan

The test of distributed RF scheme (DRFS) for ILC was carried out at the superconducting RF test facility in KEK (KEK-STF). The LLRF system and two klystron units were installed in the same tunnel as SRF cavities. The vector-sum control for two cavities was done by using the micro-TCA digital feedback board. This board was the same one developed for the compact-ERL at KEK, but the software was changed for pulse operation. The result of the performance will be reported.

MOPC156

Operation Test of Distributed RF System with Circulator-less Waveguide Distribution in S1-Global Project at STF/KEK

klystron, feedback, superconducting-cavity, linac

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.

MOPC157

Performance of LLRF System at S1-Global in KEK*

controls, diagnostics, klystron, cryogenics

451

S. Michizono, D.A. Arakawa, S. Fukuda, E. Kako, H. Katagiri, T. Matsumoto, T. Miura, Y. Yano
KEK, Ibaraki, Japan

Vector-sum control was carried out at S1-Global. The rf stabilities of 0.007% in amplitude and 17 mdeg. in phase are obtained. Various diagnostics (such as on-line quench pulse detector, dynamic detuning monitor and so on) is implemented. The IF-mixture system, where 3 intermediate frequencies (IF) are used and the number of ADCs can be reduced, was used as rf waveform monitors. These monitors are used for the performance analysis. Quench phenomena observed at the high-gradient operation are also analyzed from the view point of dynamic change in loaded Q and cavity detuning during rf pulse.

MOPC160

Digital LLRF for IFMIF-EVEDA

LLRF, controls, rfq, resonance

457

A. Salom, A. Arriaga, J.C. Calvo, I. Kirpitchev, P. Méndez, D. Regidor, M. Weber
CIEMAT, Madrid, Spain
A. Mosnier
CEA/IRFU, Gif-sur-Yvette, France
F. Pérez
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

The IFMIF-EVEDA project aims to build a prototype accelerator (deuteron, 9MeV, 125mA) to be located at Rokkasho, Japan, for design validation of the IFMIF Accelerator. CIEMAT from Madrid, Spain, is in charge of providing the RF systems for this prototype accelerator. The LLRF will adjust the phase and amplitude of the RF drive and the resonance frequency of the cavities. This paper summarizes its main characteristics and Control System integrated in EPICS. The hardware is based on a commercial FPGA board, an analog front end and a local timing system. Each LLRF system will control and diagnose two RF chains and it will handle the RF fast Interlocks (vacuum, arcs, reflected power and multipacting). A specific LLRF will be developed for the special case of the RFQ cavity, with one Master LLRF and three Slave LLRFs to feed the 8 RF chains of the cavity. The conceptual design and other capabilities of the system like automatic conditioning, frequency tuning for startup and field flatness of the RFQ, etc, will be shown in this paper together with the first low power test results of the LLRF prototype and the performance of the Control System.

MOPC161

Challenges for the Low Level RF Design for ESS

LLRF, controls, klystron, linac

460

A.J. Johansson
Lund University, Lund, Sweden
R. Zeng
ESS, Lund, Sweden

The European Spallation Source (ESS) is a planned neutron source to be built in Lund, Sweden, which is planned to produce the first neutrons in 2019. It will have an average beam power at the target of 5 MW, an average current along the Linac of 50 mA, and a pulse repetition rate and length of 20 Hz and 2 ms, respectively. The Linac will have around 200 LLRF stations employed to control a variety of RF cavities such as RFQ, DTL, spoke and elliptical superconducting cavities. The challenges on LLRF systems are mainly the high demands on energy efficiency on all parts of the facility, an operational goal of 95% availability of the facility and a comparably short time from start of final design to commissioning. Running with long pulses, high current and spoke cavities also brings new challenges on LLRF design. In this paper we will describe the consequences these challenges have on the LLRF system, and the proposed solutions and development projects that have started in order to reach these demands.

MOPC163

Low-level RF Control System for the Taiwan Photon Source

LLRF, controls, low-level-rf, SRF

463

M.-S. Yeh
NSRRC, Hsinchu, Taiwan

The low-level RF (LLRF) control system is an essential component of the RF system for Taiwan Photon Source. The LLRF control system will perform various functions including control loops for the cavity gap voltage and the phase feedback, RF system interlock protection and the diagnostics for a machine trip. The LLRF system is manufactured in house using the most recent commercial RF chips. The LLRF system has an analogue architecture similar to that used in the 1.5-GeV Taiwan Light Source (TLS). An overview of the system architecture and its functionality is presented herein.

MOPC164

Upgrade of the ISIS Synchrotron Low Power RF System

controls, feedback, ion, synchrotron

466

A. Seville, N.E. Farthing, I.S.K. Gardner, R.J. Mathieson, J.W.G. Thomason
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
D.B. Allen
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

The ISIS synchrotron at the Rutherford Appleton Laboratory in the UK now routinely uses a dual harmonic RF system to accelerate beam currents in excess of 230 uA to run two target stations simultaneously. In order to give more stable control of the phase of the RF voltage at each of the fundamental (1RF) and second harmonic (2RF) cavities, changes have been made to the low power RF (LPRF) control systems. In addition to this a new FPGA based master oscillator has been commissioned for the first time, and further changes using digital technologies to replace other components of the LPRF system are to be investigated. This paper reports on the LPRF hardware commissioning and reliability.

MOPC165

Digital Low Level RF Development at Daresbury Laboratory

controls, LLRF, linac, beam-loading

469

P.A. Corlett, L. Ma, A.J. Moss
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Digital LLRF development using Field Programmable Gate Arrays (FPGAs) is a new activity at Daresbury Laboratory. Using the LLRF4 development board, designed by Larry Doolittle of Lawrence Berkeley National Laboratory, a full featured control system incorporating fast feedback loops and a feed-forward system has been developed for use on the ALICE (Accelerators and Lasers in Combined Experiments) energy recovery linac. Technical details of the system are presented, along with experimental measurements.

MOPO004

A Longitudinal Kicker Cavity for a Bunch-by-bunch Feedback System at ELSA

kicker, simulation, feedback, impedance

484

N. Heurich, W. Hillert, A. Roth, R. Zimmermann
ELSA, Bonn, Germany

At the Electron Stretcher Facility ELSA of Bonn University, a longitudinal bunch-by-bunch feedback system is currently being installed in order to damp multibunch instabilities and to enable a future intensity upgrade of up to 200 mA. As a main component, a longitudinal kicker cavity was developed and manufactured. The kicker requires a bandwidth of 250~MHz taking into account the bunch spacing of 2 ns at ELSA. Existing designs used at other facilities were optimized in view of the considerably larger bunch lenght at ELSA. The choice of 1.125 GHz as a center frequency is a result of these considerations. With the resulting low quality factor, the design had to be optimized in order to maximize the shunt impedance. The longitudinal feedback is succesfully working with the prototype installed in the stretcher ring. The design and detailed simulations of the geometry are discussed and laboratory measurements are presented.

MOPO018

Active Beam Current Stabilization in the Cornell ERL Prototype Injector

laser, feedback, gun, cathode

523

F. Löhl, P. Szypryt
CLASSE, Ithaca, New York, USA

In order to operate the Cornell ERL prototype injector at beam currents beyond 10 mA, the beam current has to be highly stable. The reason is that fast beam current fluctuations generate transient effects in the DC gun voltage as well as in the fields of subsequent superconducting cavities, which can lead to excessive beam loss or to trips of subsystems. Therefore, a feedback scheme was developed which uses the signal of a beam current monitor as an input, and applies appropriate corrections to a Pockels cell installed within the laser path of the photo-injector laser. In this paper, high current results achieved with this feedback scheme are presented.

MOPS015

40-80 MHz Muon Front-End for the Neutrino Factory Design Study

solenoid, factory, lattice, target

628

G. Prior, S.S. Gilardoni
CERN, Geneva, Switzerland
A.E. Alexandri
University of Patras, Rio, Greece

Funding: EU FP7 EUROnu WP3. CERN summer student programme.
To understand better the neutrino properties, machines able to produce an order of 10²¹ neutrinos per year have to be built. One of the proposed machine is called a neutrino factory. In this scenario, muons produced by the decay of pions coming from the interaction of a proton beam onto a target are accelerated to energies of several GeV and injected in a storage ring where they will decay in neutrinos. The so-called front-end section of the neutrino factory is conceived to reduce the transverse divergence of the muon beam and to adapt its temporal structure to the acceptance of the downstream accelerators to minimize losses. We present a re-evaluation of the muon front-end scenario which used 40-80 MHz radio-frequency cavities capturing one sign at a time in a single-bunch to bucket mode. The standard software environment of the International Study for the Neutrino Factory (IDS-NF) has been used, for comparison of its performance with the IDS-NF baseline front-end design which operates with higher frequency (330-200 MHz) capturing in a train of alternated sign the muons bunches.

MOPS030

Beam Dynamics of the FRANZ Bunch Compressor using Realistic Fields with a Focus on the Rebuncher Cavities

linac, dipole, simulation, focusing

667

D. Noll, L.P. Chau, M. Droba, O. Meusel, H. Podlech, U. Ratzinger, C. Wiesner
IAP, Frankfurt am Main, Germany

Funding: Work supported by HIC for FAIR.
The ARMADILLO bunch compressor currently being designed at IAP is capable of reaching a longitudinal pulse compression ratio of 45 for proton beams of 150 mA at 2 MeV. It will provide one nanosecond proton pulses with a peak current of 7.7 A. The system guides nine linacμbunches deflected by a 5 MHz rf kicker and uses four dipole magnets - two homogeneous and two with field gradients - to merge them on the target. For longitudinal focusing and an energy variation of ±200 keV two multitrack rf cavities are included. ARMADILLO will be installed at the end of the Frankfurt Neutron Source FRANZ making use of the unique 250 kHz time structure. This contribution will provide an overview of the layout of the system as well as recent advances in component design and beam dynamics of the compressor.

MOPS038

3D Beam Dynamic Simulation in Heavy Ion Superconducting Drift Tube Linac

simulation, focusing, ion, linac

685

A.V. Samoshin, S.M. Polozov
MEPhI, Moscow, Russia

The superconducting (SC) linac conventionally consists of some different classes of the identical cavities. Each cavity is based on a SC structure with a high accelerating gradient. The low charge state beams require stronger transverse focusing. This focusing can be reached with the help of SC solenoid lenses. In this paper beam dynamics simulation obtain by smooth approximation and full field. Traditionally only the Coulomb field is taken into account for low energy beams. In this paper the computer simulation of heavy ion beam dynamics in superconducting (SC) linac will carried out by means of the "particle-in-cell" method. Simulation results will present.

MOPS047

Studies of Transverse Single-pass Beam Breakup in E-Linac

HOM, linac, dipole, emittance

706

D. Kaltchev, R.A. Baartman, Y.-C. Chao, P. Kolb, S.R. Koscielniak, L. Merminga, A.K. Mitra, V. Zvyagintsev
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

Time-domain simulations of single-pass transverse beam-breakup (BBU) effects in E-linac are described. We use dipole-HOM parameters for the 9-cell cavity obtained with Particle Studio to evaluate the rms bunch orbit offsets at linac exit. Finding the multi-bunch orbit contribution to machine emittance as a function of the average beam current allows to evaluate the performance of two cavity models for two different modes of machine operation.

MOPS051

Modeling of the Beam Break Up Instability for BERLinPro*

linac, optics, solenoid, HOM

718

Y. Petenev, A.V. Bondarenko, A.N. Matveenko
HZB, Berlin, Germany

Following funding approval late 2010, Helmholtz-Zentrum Berlin officially started Jan. 2011 the design and construction of the Berlin Energy Recovery Linac Project BERLinPro. The initial goal of this compact ERL is to develop the ERL accelerator physics and technology required to accelerate a high-current low emittance beam. In this work the threshold current of the Beam Break Up (BBU) instability was calculated for the BERLinPro. The comparison of two 100 MeV linacs based on different type of superconducting cavities is made. Different methods of BBU suppression are investigated (e.g. the influence of solenoid, pseudo-reflector and quadruple triplets in the linac structure on the BBU threshold).

MOPS066

Collective Effects in the MAX IV 3 GeV Ring

impedance, damping, storage-ring, synchrotron

754

P.F. Tavares
MAX-lab, Lund, Sweden
T.F. Günzel
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

We present calculations of collective instability effects in the 3 GeV electron storage ring of the MAX IV facility currently under construction in Lund, Sweden. The storage ring is designed to deliver ultra-low emittance down to 0.24 nm rad so as to provide high brightness synchrotron radiation from undulators. This is achieved in a comparatively small machine (528 m circumference) through the use of a multi-bend achromat lattice and a compact magnet design featuring multi-purpose narrow gap magnet blocks. This design features small dispersion leading to low momentum compaction, which, together with the small circular (11 mm radius) chambers, poses a challenge to reach the design current (500 mA in 176 bunches) without exciting instabilities and degrading beam parameters due to the interaction with the machine impedance. Particularly important are multi-bunch resistive wall effects in the NEG coated copper chamber as well single-bunch instabilities driven by the broad-band impedance. A low RF frequency (100 MHz) and harmonic cavities are foreseen to lengthen the bunches and increase instability thresholds.

MOPS080

Comparison of the Current LHC Collimators and the SLAC Phase 2 Collimator Impedances

impedance, coupling, simulation, collimation

790

H.A. Day, R.M. Jones
UMAN, Manchester, United Kingdom
F. Caspers, H.A. Day, E. Métral, B. Salvant
CERN, Geneva, Switzerland

One of the key sources of transverse impedance in the LHC has been the secondary graphite collimators that sit close to the beam at all energies. This limits the stable bunch intensity due to transverse coupled-bunch instabilities and transverse mode coupling instability. To counteract this, new secondary collimators have been proposed for the phase II upgrade of the LHC collimation system. A number of designs based on different jaw materials and mechanical designs have been proposed. A comparison of the beam coupling impedance of these different designs derived from simulations are presented, with reference to the existing phase I secondary collimator design.

MOPS082

Some Considerations on the Choice of Frequency and Geometrical Beta in High Power Proton Linacs in the Context of Higher Order Modes

HOM, linac, simulation, proton

793

M. Schuh, F. Gerigk
CERN, Geneva, Switzerland
M. Schuh
MPI-K, Heidelberg, Germany
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Several high power superconducting (SC) proton linear accelerators are currently in the design stage around the world, such as for example the European Spallation Source (ESS) in Lund, Project X at Fermilab, the European ADS demonstrator MYRRAH in Mol and the Superconducting Proton linac (SPL) at CERN. In this contribution, the influence of Higher Order Modes (HOMs) in elliptical SC cavities is discussed as a function of the operation frequency, the number of cells and the geometrical beta of the cavity. Based on cavity design data beam dynamics simulations are executed for different linac layouts to quantify the influence of HOMs.

MOPS086

Beam Breakup Simulation for the PEP-X ERL

HOM, emittance, simulation, recirculation

805

Y. Jiao, Y. Cai, A. Chao
SLAC, Menlo Park, California, USA

Funding: The work is supported by the U.S. Department of Energy under contract No. DE-AC02-76SF00515.
The transverse beam breakup (BBU) is one of the dominant factors in ERL for the available beam current. A tracking code built in Matlab is developed and benchmarked by comparing with the analytical solutions with the simple model. Study on the threshold current and emittance growth due to the transverse BBU for PEP-X ERL are presented in this paper.

MOPZ007

A Non-scaling Fixed Field Alternating Gradient Accelerator for the Final Acceleration Stage of the International Design Study of the Neutrino Factory

kicker, extraction, injection, lattice

832

J.S. Berg
BNL, Upton, Long Island, New York, USA
M. Aslaninejad, J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
N. Bliss, M.A. Cordwell, T.J. Jones
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
A.A. Muir
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H. Witte
JAI, Oxford, United Kingdom

Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The International Design Study of the Neutrino Factory (IDS-NF) has recently completed its Interim Design Report (IDR), which presents our current baseline design of the neutrino factory. To increase the efficiency and reduce the cost of acceleration, the IDR design uses a linear non-scaling fixed field alternating gradient accelerator (FFAG) for its final acceleration stage. We present the current lattice design of that FFAG, including the main ring plus its injection and extraction systems. We describe parameters for the main ring magnets, kickers, and septa, as well as the power supplies for the kickers. We present a first pass at an engineering layout for the ring and its subsystems.

MOPZ009

The Muon Linac for the International Design Study for the Neutrino Factory

linac, cryomodule, factory, lattice

838

A. Kurup, M. Aslaninejad, C. Bonţoiu, J.K. Pozimski
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
K.B. Beard
Muons, Inc, Batavia, USA
S.A. Bogacz, V.S. Morozov
JLAB, Newport News, Virginia, USA

The first stage of muon acceleration in the Neutrino Factory utilises a superconducting linac to accelerate muons from 244 MeV to 900 MeV. The linac is split into three types of cryomodules with decreasing magnetic fields and increasing amounts of RF voltage but with the design of the superconducting solenoid and RF cavities being the same for all cryomodules. The current status of the muon linac for the International Design Study for the Neutrino Factory will be presented including a final lattice design of the linac; electromagnetic simulations; and a preliminary cost estimate.

MOPZ011

An Automated Conditioning System for the MUCOOL Experiments at Fermilab

controls, pick-up, vacuum, collider

844

A. Kurup
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

The MUCOOL project aims to study RF cavities for the Neutrino Factory and the Muon Collider. The large emittance muon beams in these accelerators require high-gradient RF cavities at low-frequencies and they need to operate in the presence of relatively strong magnetic fields. MUCOOL is conducting a number of tests on 805MHz and 201 MHz cavities in order to develop a technology that can meet all of these requirements. An automated conditioning system was developed for the 805MHz test program for MUCOOL. This system was designed to replicate the logic a human operator would use when conditioning an RF cavity and to provide automated logging of the conditioning process. This paper describes the hardware and software of the system developed.

MOPZ012

The International Design Study for the Neutrino Factory

factory, target, proton, storage-ring

847

J.K. Pozimski, A. Kurup, K.R. Long
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
J.S. Berg
BNL, Upton, Long Island, New York, USA

The International Design Study for the Neutrino Factory (the IDS-NF) has recently completed the Interim Design Report* (IDR) for the facility as a step on the way to the Reference Design Report (RDR). The IDR has two functions: it marks the point in the IDS-NF at which the emphasis turns to the engineering studies required to deliver the RDR and it documents the present baseline design for the facility which will provide 10²¹ muon decays per year from 25 GeV stored muon beams. The facility will serve two neutrino detectors; one situated at source-detector distance of between 3000–5000 km, the second at 7000–8000 km. The conceptual design of the accelerator facility will be described and its performance will be presented. The steps that the IDS-NF collaboration has taken since the IDR was finalized and plans to take to prepare the RDR will also be presented.
* IDS-NF-020: https://www.ids-nf.org/wiki/FrontPage/Documentation?action=AttachFile&do=get&target=IDS-NF-020-v1.0.pdf
Submitted on behalf of the IDS-NF collaboration

MOPZ028

Solid Absorber Program Status for MICE Step IV

emittance, status, simulation, insertion

859

P. Snopok
IIT, Chicago, Illinois, USA
J.H. Cobb
JAI, Oxford, United Kingdom
G.T. Kafka
Illinois Institute of Technology, Chicago, Illinois, USA
C.T. Rogers
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

Funding: Work is supported by the Science and Technology Facilities Council and the U.S. Department of Energy.
In the Muon Ionization Cooling Experiment (MICE), muons are cooled by passing through material and then through RF cavities to compensate for the energy loss, which reduces the transverse emittance. In addition to demonstrating the transverse emittance reduction using flat solid absorbers, it is also planned to demonstrate longitudinal emittance reduction via emittance exchange in MICE by using a solid wedge-shaped absorber in MICE Step IV. The current status of the simulation and design effort for both flat and wedge-shaped solid absorbers is summarized.

MOPZ029

Aperture Windows in High-Gradient Cavities for Accelerating Low-Energy Muons

linac, septum, target, vacuum

862

S.S. Kurennoy, A.J. Jason, W.M. Tuzel
LANL, Los Alamos, New Mexico, USA

A high-gradient linear accelerator for accelerating low-energy muons and pions in a strong solenoidal magnetic field has been proposed for homeland defense and industrial applications*. The acceleration starts immediately after collection of pions from a target in a solenoidal magnetic field and brings muons to a kinetic energy of about 200 MeV over a distance of the order of 10 m. At this energy, both ionization cooling of the muon beam and its further acceleration become feasible. A normal-conducting linac with external-solenoid focusing can provide the required large beam acceptances. The linac consists of independently fed zero-mode (TM010) RF cavities with wide beam apertures closed by thin conducting windows. The high gradients lead to significant heat deposition on the aperture windows. Here we explore options for the edge-cooled thin windows in the zero-mode cavities. Electromagnetic and thermal-stress computations are complemented by thermal-test experiments to select the best solution for the aperture windows.
* S.S. Kurennoy, A.J. Jason, H. Miyadera, “Large-Acceptance Linac for Accelerating Low-Energy Muons,” Proc. of IPAC10, p. 3518 (2010).

TUOAA03

The Linac4 Project at CERN

linac, DTL, rfq, klystron

900

M. Vretenar, L. Arnaudon, P. Baudrenghien, C. Bertone, Y. Body, J.C. Broere, O. Brunner, M.C.L. Buzio, C. Carli, F. Caspers, J.-P. Corso, J. Coupard, A. Dallocchio, N. Dos Santos, R. Garoby, F. Gerigk, L. Hammouti, K. Hanke, M.A. Jones, I. Kozsar, J.-B. Lallement, J. Lettry, A.M. Lombardi, L.A. Lopez Hernandez, C. Maglioni, S.J. Mathot, S. Maury, B. Mikulec, D. Nisbet, C. Noels, M.M. Paoluzzi, B. Puccio, U. Raich, S. Ramberger, C. Rossi, N. Schwerg, R. Scrivens, G. Vandoni, J. Vollaire, S. Weisz, Th. Zickler
CERN, Geneva, Switzerland

As the first step of a long-term programme aiming at an increase in the LHC luminosity, CERN is building a new 160 MeV H⁻ linear accelerator, Linac4, to replace the ageing 50 MeV Linac2 as injector to the Proton-Synchrotron Booster (PSB). Linac4 is an 86-m long normal-conducting linac made of an H⁻ source, a Radio Frequency Quadrupole (RFQ), a chopping line and a sequence of three accelerating structures: a Drift-Tube Linac (DTL), a Cell-Coupled DTL (CCDTL) and a Pi-Mode Structure (PIMS). The civil engineering has been recently completed, and construction of the main accelerator components has started with the support of a network of international collaborations. The low-energy section up to 3 MeV including a 3-m long 352 MHz RFQ entirely built at CERN is in the final construction phase and is being installed on a dedicated test stand. The present schedule foresees beam commissioning of the accelerator in the new tunnel in 2013/14; the moment of connection of the new linac to the CERN accelerator chain will depend on the LHC schedule for long shut-downs.

Slides TUOAA03 [10.347 MB]

TUYA02

LHC Upgrade Plans: Options and Strategy

luminosity, quadrupole, collider, cryogenics

908

L. Rossi
CERN, Geneva, Switzerland

Presentation of options for future luminosity and/or energy upgrades of the LHC ring. The presentation should cover the different ideas, short term, medium term and long term, and discuss the research programme that is needed to prepare the upgrades.

Slides TUYA02 [5.139 MB]

TUYA03

Stochastic Cooling of a High Energy Collider

simulation, kicker, pick-up, luminosity

913

M. Blaskiewicz, J.M. Brennan, R.C. Lee, K. Mernick
BNL, Upton, Long Island, New York, USA

Three dimensional stochastic cooling was successfully implemented at the Relativistic Heavy Ion Collider to overcome emittance growth from intra-beam scattering. The talk reports on the experience of operating a collider with continuous cooling. The application of such techniques to other hadron machine (e.g. LHC) will be discussed.

Slides TUYA03 [1.350 MB]

TUODA03

The Status of the ALICE Accelerator R&D Facility at STFC Daresbury Laboratory

FEL, radiation, electron, diagnostics

934

F. Jackson, D. Angal-Kalinin, R. Bate, R.K. Buckley, S.R. Buckley, J.A. Clarke, P.A. Corlett, D.J. Dunning, J.-L. Fernández-Hernando, A.R. Goulden, S.F. Hill, D.J. Holder, S.P. Jamison, J.K. Jones, L.B. Jones, A. Kalinin, S. Leonard, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, A.J. Moss, B.D. Muratori, T.T. Ng, J.F. Orrett, S.M. Pattalwar, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, A.D. Smith, R.J. Smith, S.L. Smith, N. Thompson, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
P. Harrison, G.M. Holder, A.L. Schofield, P. Weightman, R.L. Williams, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
M.D. Roper
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
M. Surman
STFC/DL/SRD, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Science and Technology Facilities Council
The ALICE accelerator, the first energy recovery machine in Europe, has recently demonstrated lasing of an infra-red free electron laser (IR-FEL). The current status of the machine and recent developments are described. These include: lasing of the IR-FEL, a programme of powerful coherent terahertz radiation research, electro-optic diagnostic techniques, development of high precision timing and distribution system, implementation of digital low level RF control. ALICE also serves as an injector for the EMMA non-scaling FFAG machine.

Slides TUODA03 [1.648 MB]

TUYB01

First Results from the EMMA Experiment

acceleration, electron, injection, septum

951

S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

Report on first commissioning results and operational experience with EMMA, the world's first nonscaling FFAG. In particular review the effect of resonance crossing, and the efficiency of serpentine acceleration.

Slides TUYB01 [9.201 MB]

TUZB01

Superconducting RF Technology for Proton and Ion Accelerators

linac, cryomodule, SRF, proton

966

G. Devanz
CEA/DSM/IRFU, France

The worldwide status of superconducting RF cavities and cryomodules for low velocity ion and proton particles is reviewed, with emphasis on the construction and tests of prototypes. A number of different multicell structures at a range of operating frequencies have been successfully realized. This review will cover the progress of several facilities under construction or being proposed: Spiral2, IFMIF-EVEDA, SPL, ESS, FRIB and ADS drivers.

Slides TUZB01 [10.630 MB]

TUPC020

Alignment and Wake Field Issues in the CLIC RTML

emittance, linac, lattice, wakefield

1039

F. Stulle, S. Döbert, A. Latina, D. Schulte
CERN, Geneva, Switzerland

At main linac injection the particle beams need to stay within tight tolerances for the transverse emittances and the pointing stability. We study how these tolerances influence alignment requirements for the RTML components and the stability of the beams entering the RTML. An emphasize is put on the booster linac and the RF cavities of the second bunch compression stage since short and long range wake fields might strongly influence beam dynamics in these parts of the RTML.

TUPC021

The CLIC Feasibility Demonstration in CTF3

linac, acceleration, electron, ion

1042

P.K. Skowroński, J. Barranco, S. Bettoni, B. Constance, R. Corsini, A.E. Dabrowski, M. Divall Csatari, S. Döbert, A. Dubrovskiy, O. Kononenko, M. Olvegård, T. Persson, A. Rabiller, F. Tecker
CERN, Geneva, Switzerland
E. Adli
University of Oslo, Oslo, Norway
W. Farabolini
CEA/DSM/IRFU, France
R.L. Lillestol
NTNU, Trondheim, Norway
T. Muranaka, A. Palaia, R.J.M.Y. Ruber
Uppsala University, Uppsala, Sweden

The objective of the CLIC Test Facility CTF3 is to demonstrate the feasibility issues of the CLIC two-beam technology: the efficient generation of a very high current drive beam, used as the power source to accelerate the main beam to multi-TeV energies with gradient over 100MeV/m, stable drive beam deceleration over long distances. Results on successful beam acceleration with over 100 MeV/m energy gain are shown. Measurements of drive beam deceleration over a chain of Power Extraction Structures are presented. The achieved RF power levels, the stability of the power production and of the deceleration are discussed. Finally, we overview the remaining issues to be shown until the end of 2011.

TUPC025

Calibration Errors in the Cavity Beam Position Monitor System at the ATF2

radio-frequency, lepton, closed-orbit, simulation

1051

F.J. Cullinan, S.T. Boogert, N.Y. Joshi, A. Lyapin
JAI, Egham, Surrey, United Kingdom

It has been shown at the Accelerator Test Facility at KEK, that it is possible to run a system of 37 cavity beam position monitors (BPMs) and achieve high working resolution. However, stability of the calibration constants (position scale and radio frequency (RF) phase) over a three/four week running period is yet to be demonstrated. During the calibration procedure, random beam jitter gives rise to a statistical error in the position scale and slow orbit drift in position and tilt causes systematic errors in both the position scale and RF phase. These errors are dominant and have been evaluated for each BPM. The results are compared with the errors expected after a tested method of beam jitter subtraction has been applied.

TUPC026

Status of the Crab Cavity Design for the CLIC

damping, wakefield, dipole, coupling

1054

P.K. Ambattu, G. Burt, A.C. Dexter
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
V.A. Dolgashev
SLAC, Menlo Park, California, USA
A. Grudiev
CERN, Geneva, Switzerland
R.M. Jones
UMAN, Manchester, United Kingdom
P.A. McIntosh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

RF design of a crab cavity (2π/3, 11.9942 GHz) for the Compact Linear Collide (CLIC) is presented. As part of the UK-CLIC collaboration, CERN is building two copper prototypes, designed by Lancaster University / Cockcroft Institute. The first prototype to be made will be a 12 cell undamped cavity and the second will be waveguide damped cavity. The RF test at CERN will help characterisation of the dipole mode with X-band RF pulses of 15 MW peak power and pulse length of ~242 ns. Since the cavity frequency and phase advance per cell are identical to those of the CLIC main linac, the first prototype could exploit CERN’s X-band cavity characterisation facilities. A fully damped cavity will be required for the actual machine in order to meet the luminosity specs. The damped prototype will use an identical coupler type as the undamped one, but the cells will have damping waveguides with / without dielectric material.

TUPC054

LHeC ERL Design and Beam-dynamics Issues

linac, optics, emittance, HOM

1120

S.A. Bogacz, I. Shin
JLAB, Newport News, Virginia, USA
D. Schulte, F. Zimmermann
CERN, Geneva, Switzerland

We discuss machine and beam parameter choices for a Linac-Ring option of the Large Hadron electron Collider (LHeC) based on the LHC. With the total wall-plug power limited to 100 MW and a target current of about 6 mA the desired luminosity of 10³3 cm^-2 s^-1 can be reached, providing one exploits unique features of the Energy Recovery Linac (ERL). Here, we describe the overall layout of such ERL complex located on the LHC site. We present an optimized multi-pass linac optics enabling operation of the proposed 3-pass Recirculating Linear Accelerator (RLA) in the Energy Recovery mode. We also describe emittance preserving return arc optics architecture; including layout and optics of the arc switch-yard. Furthermore, we discuss importance of collective effects such as: beam breakup in the RLA, as well as ion accumulation, with design-integrated mitigation measures, and the electron-beam disruption in collision. Finally, a few open questions are highlighted.

TUPC058

Design of a Chirping Cell Attached RF Gun for Ultrashort Electron Generation

gun, electron, laser, radiation

1129

K. Sakaue, K. Tamai, M. Washio
RISE, Tokyo, Japan
J. Urakawa
KEK, Ibaraki, Japan

Funding: Work supported by JSPS Grant-in-Aid for Scientific Research (A) 10001690
We have been developing an S-band photocathode rf electron gun at Waseda university. Our rf-gun cavity was firstly designed by BNL and then, modified by our group. In this paper, we will introduce a newly designed rf-gun cavity with energy chirping cell. To generate an energy chirped electron bunch, we attached extra-cell for 1.6cell rf-gun cavity. Cavity design was done by Superfish and particle tracing by PARMELA. By optimizing the chirping cell, we observed linear chirped electron bunch. The front electron have lower energy than rear. Then transporting about 2m, the bunch can be compressed down to 200fsec electron bunch with the charge of 160pC. This ultrashort bunch will be able to use for generating CSR THz radiation, pumping some material to be studied by pulse radiolysis method, and so on. In this conference, the design of chirping cell attached rf-gun, the results of tracing simulation and plan of manufacturing will be presented.

TUPC059

Study on Energy Compensation by RF Amplitude Modulation for High Intense Electron Beam Generated by a Photocathode RF-Gun

laser, beam-loading, electron, gun

1132

Y. Yokoyama, T. Aoki, K. Sakaue, T. Suzuki, M. Washio, T. Yamamoto
RISE, Tokyo, Japan
H. Hayano, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
R. Kuroda
AIST, Tsukuba, Ibaraki, Japan

Funding: Work supported by JSPS Grant-in-Aid for Scientific Research(A)10001690 and JST Quantum Beam Program.
At Waseda University, we have been studying a high quality electron beam generation and its application experiments with a Cs-Te photocathode RF-Gun. To generate more intense and stable electron beam, we have been developing the cathode irradiating UV laser which consists of optical fiber amplifier and LD pumped amplifier. As the result, more than 100 multi-bunch electron beam with 1nC each bunch charge was obtained. However, it is considered that the accelerating voltage will decrease because of the beam loading effect. So we have studied the RF amplitude modulation technique to compensate the beam energy difference. The energy difference will caused by transient accelerating voltage in RF-Gun cavity and beam loading effect. As the result of this compensation method, the energy difference has been compensated to 1%p-p, while 5%p-p without compensation. In this conference, we will report the details of energy compensation method using the RF amplitude modulation, the results of beam experiments and the future plans.

TUPC060

A Multi-mode RF Photocathode Gun

gun, cathode, injection, electron

1135

S.V. Kuzikov, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia
J.L. Hirshfield
Yale University, Physics Department, New Haven, CT, USA
Y. Jiang
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
V. Vogel
DESY, Hamburg, Germany

A photocathode injection gun based on standard emittance compensating techniques and driven by several (N ≥ 2) harmonically related RF sources is considered. Multi-harmonic excitation can provide high-quality flatness in time of the field at the cathode when a bunch is being injected. This allows one to obtain ≥1 nC, 20-40 ps electron bunches with preservation of low emittance. Another advantage is a reduction of Ohmic losses and the required input RF power (for a given cathode field). Preliminary calculations show that input power in a three-mode cavity (0.65 GHz, 1.3 GHz, 2.6 GHz) is nearly half the power needed to feed a single mode with the same cathode field. A further appealing property is the predicted increase of breakdown threshold due to a reduction of surface exposure time to high fields in a symmetric cavity, and due to the so-called anode-cathode effect in a longitudinally asymmetric cavity. These properties may help one to reach bunch energies as high as 3-5 MeV after the first half cell.

TUPC077

Investigations on High Sensitive Sensor Cavity for Longitudinal and Transversal Schottky for the CR at FAIR

coupling, dipole, resonance, simulation

1180

M. Hansli, A. Angelovski, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
W. Ackermann, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
P. Hülsmann
GSI, Darmstadt, Germany

Funding: Funded by the Federal Ministry of Education and Research (BMBF): 06DA90351
For the Collector Ring (CR) at the FAIR (Facility for Antiproton and Ion Research) accelerator complex a sensitive Schottky sensor is required. The CR covers different modes of operation, like pre-cooling of antiprotons at 3 GeV, pre-cooling of rare isotope beams at 740 MeV/u and an isochronous mode for mass measurements. For longitudinal Schottky measurements the concept of a resonant cavity had been introduced [Hansli2011]. Due to limited space inside the ring, the integration of transversal Schottky analysis into this cavity is desired. In this paper the demands and required changes to implement also transversal Schottky measurements are discussed. An analysis of the expected signal characteristics featuring equivalent circuit is shown, as well as numerical full wave simulations of the cavity.
* M. Hansli, A. Penirschke, R. Jakoby, W. Kaufmann, W. Ackermann, T. Weiland, "Conceptual Design of a High Sensitive Versatile Schottky Sensor for the Collector Ring at FAIR", DIPAC2011.

TUPC097

Status of Cold Cavity Beam Position Monitor for STF

linac, cryomodule, vacuum, coupling

1236

E.-S. Kim, A. Heo
KNU, Deagu, Republic of Korea
H. Hayano
KEK, Ibaraki, Japan

Cold cavity BPM was developed to meet high position resolution and bunch to bunch measurement time. It is designed based on re-entrant cavity and has Low-Q to achieve short signal decay time in L-band frequency with large aperture as 78mm. The beam test was performed to demonstrate position resolution at ATF main linac, which is operating with 1.6nC bunch charge, while BPM will be installed inside the ILC cyomodule with 3.2nC spacing 369ns like as ILC at STF. Stripline BPMs, ML2P and ML3P installed upstream and downstream of the BPM’s location respectively were used to predict its position. Reference cavity was optimized to use for synchronous detection. We had achieved ~340nm position resolution since position resolution was estimated due to limitation of system with noise, namely in case of ideal state. We will present configuration of beam test, procedure to measure position resolution and the result on the test. Furthermore, new design will be introduced to improve signal intensity and have heavy coupling.

TUPC100

Longitudinal Beam Profile Measurement at J-PARC Separated Drift Tube Linac

beam-losses, linac, simulation, injection

1245

T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
KEK, Ibaraki, Japan
A. Miura, G.H. Wei
JAEA/J-PARC, Tokai-mura, Japan
H. Sako
JAEA, Ibaraki-ken, Japan

We measured longitudinal beam profile at Separated Drift Tube Linac (SDTL) injection part by scanning beam transmission and beamloss at the downstream of SDTL section by changing SDTL injection phase. As the beam goes to acceptance edge, part of the beam which is out of acceptance isn't accelerate and finally it is lost by hitting to beam duct. Thus beam transmission shows sliced bunch shape by acceptance edge, it is possible to reconstruct the beam bunch shape. The result shows about 60% wider profile in both phi and E direction against to design.

TUPC104

Beam Loss Detected by Scintillation Monitor

beam-losses, linac, simulation, hadron

1257

A. Miura, K. Hasegawa, T. Maruta, N. Ouchi, H. Sako
JAEA/J-PARC, Tokai-mura, Japan
Z. Igarashi, M. Ikegami, T. Miyao
KEK, Ibaraki, Japan

Ar gas proportional BLMs have measured the beam loss through operations, but they are also sensitive to background noise of X-ray emitted from RF cavities. We have tried to measure the beam loss using scintillation monitors which would bring more accurate beam loss measurements with suppression of X-ray noise. We measured beam loss using scintillation beam loss monitors. Because this scintillation BLM is sensitive for low energy gamma-rays and fast neutrons, small signals from X-rays would be also detected. As the measurement results, a good signal to noise ratio is observed for the scintillation monitor with quite low sensitivity to the background X-ray. And many single events are observed in the intermediate pulse bunch with about 600 ns as pulse width. In addition, because we fabricated the filter and integrated circuit, total amount of X-ray noise can become smaller. We obtained the good performances of scintillation BLM with small effect of X-ray noise. This monitor can be used for beam loss measurement and a knob for tuning. Furthermore, because the detail structure can be detected, this monitor could be employed for another diagnostic device.

TUPC108

Beam Diagnostics Based on Higher Order Mode for High Repetition Beam

HOM, simulation, diagnostics, single-bunch

1269

X. Luo, X.Y. Lu, F. Wang
PKU/IHIP, Beijing, People's Republic of China
F.S. He
JLAB, Newport News, Virginia, USA

The signals from the HOM ports on superconducting cavities can be used as beam position monitors. The HOM amplitude of dipole mode is proportional to the beam offset. For high repetition bunches operation, the spectrum is consist of the HOMs peaks and the peaks which is integer times of the bunch repetition. The HOMs amplitudes should be separated from the two kinds of peaks. Based on the simulation from a TESLA 2-cell cavity, the transform matrix between the HOMs amplitudes and beam offsets has been found, as well as the cavity axis. The simulation results have demonstrated that beam diagnostics based on HOMs is feasible while high repetition bunches operation.

TUPC110

Ultrashort Bunch Train Longitudinal Diagnostics using RF Deflecting Structure

diagnostics, laser, betatron, emittance

1275

Y. Yang, H. Chen, Y.-C. Du, W.-H. Huang, C. Li, L.X. Yan
TUB, Beijing, People's Republic of China

Ultrashort electron bunch train has been produced using UV laser stacking in Tsinghua University. With an S-band deflecting cavity inserted into the Tsinghua Thomson Scattering beamline, it is possible to characterize the bunch train longitudinal property. This paper briefly introduced the measurement layout in our lab and reported the recent experiment results, including bunch train profile measurement and longitudinal phase space. The main sources of error are also discussed.

TUPC111

Design of Cavity Beam Monitor at HLS

quadrupole, emittance, gun, dipole

1278

Q. Luo, Q.K. Jia, B.G. Sun, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work supported by the Natural Science Foundation of China, National “985 Project”, China Postdoctoral Science Foundation and “the Fundamental Research Funds for the Central Universities”
X-FEL requires precious control of beam position and transverse emittance. Non-destructive on-line beam diagnostic methods are required. During the upgrading of HLS a high brightness injector based on photocathode RF electron gun, which can also be used to study FEL, is installed. The cavity beam monitor system designed for the HLS photocathode RF electron gun consists of a cavity beam position monitor and a beam quadrupole moment monitor system. The cavity beam position monitor uses a re-entrant position cavity tuned to TM110 mode as position cavity and cut-through waveguides to suppress the monopole signal. Cold test results showed that position resolution of prototype BPM is better than 3 μm. Beam quadrupole moment monitor system consists of a square pill-box quadrupole moment cavity, a cylindrical pill-box reference cavity, a waveguide coupling network and a superheterodyne receiver used as front-end signal processing system. The whole system works at 5.712 GHz. Strength of quadrupole magnets is adjust to construct a matrix which can be used to work out beam parameters.

TUPC118

Test Results on Beam Position Resolution for Low-Q IP-BPM at KEK-ATF2

feedback, alignment, collider, dipole

1293

S.W. Jang, A. Heo, J.G. Hwang, E.-S. Kim, H.-S. Kim
Kyungpook National University, Daegu, Republic of Korea
H.K. Park
CHEP, Daegu, Republic of Korea

We have performed the beam tests on the beam position resolution for the Low-Q IP-BPM (Interaction Point-Beam Position Monitor) at ATF2 which is an accelerator test facility for the International Linear Collider. The main goals of KEK-ATF2 are to achieve beam size of 37 nm and beam resolution of nano-meter for beam stabilization. Resolution tests for the Low-Q IP-BPM were performed with KEK BPM doublet in Jan. 2011. We got the results of beam position resolution 70 nm during the experimental periods and will present the detailed experimental procedures and results.

TUPC119

A Comprehensive Study of Nanometer Resolution of the IPBPM at ATF2*

dipole, simulation, coupling, extraction

1296

Y.I. Kim, H. Park
Kyungpook National University, Daegu, Republic of Korea
S.T. Boogert
Royal Holloway, University of London, Surrey, United Kingdom
J.C. Frisch, D.J. McCormick, J. Nelson, T.J. Smith, G.R. White, M. Woodley
SLAC, Menlo Park, California, USA
Y. Honda, R. Sugahara, T. Tauchi, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Funding: Work supported in part by Department of Energy Contract DE-AC02-76SF00515.
High-resolution beam position monitors (IPBPMs) have been developed in order to measure the electron beam position at the focus point of ATF2 to a few nanometers in the vertical plane. To date, the IPBPM system has operated in test mode with a highest demonstrated resolution of 8.7 nm in the ATF extraction line during 2008. After expected noise source calculations there still remains 7.9 nm of noise of unexplained origin. We summarize the experimental work on the IPBPM system since this measurement and outline the possible origins of these sources. We then present a study plan to be performed at the ATF2 facility designed to identify and to improve the resolution performance and comment on the expected ultimate resolution of this system.

TUPC139

Overview of the CLIC Beam Instrumentation

linac, beam-losses, laser, instrumentation

1350

T. Lefèvre
CERN, Geneva, Switzerland

Driven by beam dynamic considerations the Compact Linear Collider (CLIC) is expected to require extremely tight tolerances on most beam parameters. An important milestone was reached in 2011 with the completion of the CLIC conceptual design report. In this context the requirements for CLIC beam instrumentation has been reviewed and studied in detail for the whole accelerator complex with the aim of demonstrating feasibility. A preliminary choice has been made for every CLIC instrument, serving as a baseline scenario for the next phase of the project which will concentrate on the detailed design, engineering and test of CLIC devices. Whenever possible existing solutions have been studied, focusing on any improvements necessary to meet the CLIC performance criteria. When no such devices exists, or if cost considerations come into play, new technologies have been under study. Several prototypes are already well advanced and are currently under test. This paper presents an overview of CLIC beam instrumentation, the possible reach of their performance and an outlook on future developments.

TUPC161

Cavity Beam Position Monitor System for ATF2

dipole, quadrupole, EPICS, extraction

1410

S.T. Boogert, R. Ainsworth, G.E. Boorman, S. Molloy
Royal Holloway, University of London, Surrey, United Kingdom
A.S. Aryshev, Y. Honda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
F.J. Cullinan, N.Y. Joshi, A. Lyapin
JAI, Egham, Surrey, United Kingdom
J.C. Frisch, D.J. McCormick, J. Nelson, T.J. Smith, G.R. White
SLAC, Menlo Park, California, USA
A. Heo, E.-S. Kim, Y.I. Kim
KNU, Deagu, Republic of Korea

The Accelerator Test Facility 2 (ATF2) in KEK, Japan, is a prototype scaled demonstrator system for the final focus required for a future high energy lepton linear collider. The ATF2 beam-line is instrumented with a total of 41 high resolution C and S band resonant cavity beam position monitors (BPM) with associated mixer electronics and digitizers. In addition 4 high resolution BPMs have been recently installed at the interaction point, we briefly describe the first operational experience of these cavities in the ATF2 beam-line. The current status of the overall BPM system is also described, with a focus on operational techniques and performance.

TUPC164

Position Determination of Closely Spaced Bunches using Cavity BPMs

single-bunch, quadrupole, linear-collider, collider

1419

N.Y. Joshi, S.T. Boogert, F.J. Cullinan, A. Lyapin
JAI, Egham, Surrey, United Kingdom

Cavity Beam Position Monitor (BPM) systems with high-Q form a major part of precision position measurement diagnostics for linear accelerators with low emittance beam. Using cavity BPMs, the position resolution of less than 100 nm has been demonstrated in single bunch mode operation. In the case of closely spaced bunches, where the decay time of the cavity is comparable to the time separation between bunches, the BPM signal from a bunch is polluted by the signal induced from the previous bunches in the same bunch-train. This paper discuss our ongoing work to develop the methods to extract the position of the closely spaced bunches using cavity BPMs. A signal subtraction code is being developed to remove the signal pollution from previous bunches and to determine the individual bunch position. Another code has been developed to simulate the BPM data for the cross check. Performance of the code is studied on the experimental and simulated data. Application of the analysis techniques to the linear colliders, such as International Linear Collider (ILC) and Compact LInear Collider (CLIC), are briefly discussed.

TUPC170

Resonant TE Wave Measurements of Electron Cloud Densities at CesrTA

resonance, electron, plasma, damping

1434

J.P. Sikora, M.G. Billing, M.A. Palmer, K.G. Sonnad
CLASSE, Ithaca, New York, USA
B.T. Carlson
CMU, Pittsburgh, Pennsylvania, USA
S. De Santis
LBNL, Berkeley, California, USA
K.C. Hammond
Harvard University, Cambridge, Massachusetts, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, and the US Department of Energy DE-FC02-08ER41538.
The Cornell Electron Storage Ring has been reconfigured as a test accelerator (CesrTA). Measurements of electron cloud densities have been made at CesrTA using the TE Wave transmission technique. However, interpretation of the data based on single pass transmission is problematic because of the reflections and standing waves produced by discontinuities in the beam pipe - from pumps, bellows, etc. that are normally present in an accelerator vacuum chamber. An alternative model is that of a resonant cavity, formed by the beampipe and its discontinuities. The theory for the measurement of plasma densities in cavities is well established. This paper will apply this theory to electron cloud measurements, present some simplified measurements on waveguide, and apply this model to the interpretation of some of the data taken at CesrTA.

TUPO002

High Flux Polarized Gamma Rays Production: First Measurements with a Four-mirror Cavity at the ATF

laser, electron, positron, damping

1446

N. Delerue, J. Bonis, I. Chaikovska, R. Chiche, R. Cizeron, M. Cohen, P. Cornebise, R. Flaminio, D. Jehanno, F. Labaye, M. Lacroix, Y. Peinaud, L. Pinard, V. Soskov, A. Variola, Z.F. Zomer
LAL, Orsay, France
T. Akagi, S. Miyoshi
Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan
S. Araki, Y. Funahashi, Y. Honda, T. Omori, H. Shimizu, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
E. Cormier
CELIA, Talence, France
T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan

Funding: ANR, IN2P3
The next generation of e+/e^- colliders will require the production of a very intense flux of gamma rays to allow polarized positrons to be produced in sufficient quantities. To demonstrate that this can be achieved a four-mirror cavity has recently been installed at the Accelerator Test Facility (ATF) at KEK to produce a high flux of polarized gamma rays by inverse Compton scattering. A four-mirror non-planar geometry is used to ensure the polarization of the gamma rays produced. The main mechanical features of the cavity are presented. A fibre amplifier is used to inject about 10W in the high finesse cavity with a gain of 1000. A digital feedback system is used to keep the cavity at the length required for the optimal power enhancement. First preliminary measurements show that on some beam crossings the interactions produce more than 25 photons with an average energy of about 24 MeV. Several upgrades currently in progress are described.

TUPO012

Stable Planner Type Four-mirror Cavity Development for X-ray Production as Basic Development of Quantum Beam Technology Program

laser, injection, superconducting-RF, target

1470

H. Shimizu, Y. Higashi, Y. Honda, J. Urakawa
KEK, Ibaraki, Japan

As the development of quantum beam technology program, a facility to produce a semi-monochromatic X-ray via inverse Compton scattering with an electron beam accelerated by a superconducting RF cavity and a fiber amplified high power laser stacked in an external optical cavity system are now under construction. To achieve high brightness of Compton X-ray, we introduced a chicane with about a 1m-long zero dispersion straight section that includes IP. Head on collision scheme improves the yield of X-ray, but to do so, a huge and stout external optical cavity system must be needed. According to this demand, we develop a quite tolerable planner type four-mirror cavity with movable mirror mount system. In this paper, results obtained by the cavity construction and also laser development activities are described.

TUPO026

Developments towards a Full Energy Recovery Linac

gun, HOM, cathode, SRF

1494

P. vom Stein, J.H. Hottenbacher, A. Metz
RI Research Instruments GmbH, Bergisch Gladbach, Germany

Energy Recovery Linacs (ERLs) are high potential candidates for driving light sources based on laser Compton scattering with high brilliance photon beams and sub pico second time structure. We report on developments for an advanced ERL design, which allows the recovery of nearly full electron beam energy up to the limits set by the energy width of the beam. This “Full” Energy Recovery Linac (FERL) allows a substantial reduction of the complexity of the accelerator systems resulting into a very compact light source design suitable for industrial and medical applications.

TUPO034

Longitudinal Stability of ERL with Two Accelerating RF Structures

linac, electron, RF-structure, simulation

1509

Ya.V. Getmanov, O.A. Shevchenko
BINP SB RAS, Novosibirsk, Russia
N. Vinokurov
NSU, Novosibirsk, Russia

Modern ERL projects use superconductive accelerating RF structures. Their RF quality is typically very high. Therefore, the RF voltage induced by electron beam is also high. In ERL the RF voltage induced by the accelerating beam is almost canceled by the RF voltage induced by the decelerating beam. But, a small variation of the RF voltage may cause the deviations of the accelerating phases. These deviations then may cause further voltage variation. Thus the system may be unstable. The stability conditions for ERL with one accelerating structure are well known [*, **]. The ERL with split RF structure was discussed recently [***, ****]. The stability conditions for such ERLs are discussed in this paper.
* L. Merminga et al.,Annu. Rev.Nucl. Part. Sci. 53 (2003) 387.
** N.A. Vinokurov et al.,Proc. SPIE 2988 (1997) 221.
*** D. Douglas, ICFA BD-Nl 26 (2001) 40.
****N.A. Vinokurov et al.,Proc. IPAC’10.

TUPO035

Beam Dynamics at the ALICE Accelerator R&D Facility

linac, FEL, simulation, booster

1512

F. Jackson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Science and Technology Facilities Council
ALICE is an energy recovery accelerator which drives an infrared free electron laser (IR FEL), based at STFC Daresbury Laboratory. Beam dynamics are of primary importance for the operation of the IR FEL, to ensure sufficient peak current with minimal energy spread and transverse emittance. Measurements of beam parameters are presented and compared with particle tracking simulations. Of particular interest in the ALICE machine is the relatively long injection line where space charge and velocity bunching effects can be significant.

TUPS014

Vacuum Performance Simulation of C-band Accelerating Structures

vacuum, linac, simulation, free-electron-laser

1548

H. Lee, M.-H. Cho, S.H. Kim, C.H. Yi
POSTECH, Pohang, Kyungbuk, Republic of Korea
W. Namkung, C.D. Park
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This work is partly supported by the MEST and POSTECH Physics BK21 program.
A C-band accelerating structure has a higher accelerating gradient than that of the S-band structure. It provides a good advantage of a shorter machine length. In order to effectively use RF power and for cost reduction, the accelerating structure should be as long as possible. We propose a 2.2-m long structure compared to 1.8-m at SACLA (SPring-8 Angstrom Compact free electron LAser). However, a longer accelerating structure has worse vacuum performance than a shorter accelerating structure. Thus, the vacuum conductance of 2.2-m long structure has to be checked. We calculate vacuum performance of the accelerating structure by 1-D analytical method and 3-D finite element method (FEM). It is shown that the vacuum performance for the 2.2-m long accelerating structure is safe enough for the XFEL LINAC.

TUPS015

ALBA Storage Ring Vacuum System Commissioning

vacuum, storage-ring, photon, synchrotron

1551

E. Al-dmour, D. Einfeld
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

The ALBA booster and storage ring vacuum system installation has been done in 2009, followed by the installation of the RF cavities and the booster to storage transfer line in 2010. Early 2011, the first phase of insertion devices (ID) installation took place, with three narrow gap NEG coated vacuum chambers have been installed, for the use of two Apple-II undulators and one conventional wiggler. On 8th of March 2011, the storage ring commissioning started and it was marked with the achievement of the first turn in the storage ring on the 9th of March and on the 1st of April 2011, 100 mA of beam current has been accumulated. During this period the vacuum system conditioning took place with very good performance. The base pressure without beam was 4·10^-10 mbar and the average pressure with 100 mA was 7.7·10^-9 mbar. The results of the conditioning together with the latest developments are introduced.

TUPS021

Simulations and Vacuum Tests of a CLIC Accelerating Structure

vacuum, simulation, ion, damping

1569

C. Garion
CERN, Geneva, Switzerland

The Compact LInear Collider, under study, is based on room temperature high gradient structures. The vacuum specificities of these cavities are low conductance, large surface areas and a non-baked system. The main issue is to reach UHV conditions (typically 10^-7 Pa) in a system where the residual vacuum is driven by water outgassing. A finite element model based on an analogy thermal/vacuum has been built to estimate the vacuum profile in an accelerating structure. Vacuum tests are carried out in a dedicated set-up, the vacuum performances of different configurations are presented and compared with the predictions.

TUPS068

The GSI RF Maintenance & Diagnostics Project

LLRF, diagnostics, status, controls

1695

K.-P. Ningel, H. Klingbeil, B. Zipfel
GSI, Darmstadt, Germany
A. Honarbacht, M. Proske
Ubisys Technologies GmbH, Düsseldorf, Germany
H. Veldman
LogiTrue, Polokwane, South Africa

From time-to-time, microcontroller- and FPGA-based LLRF electronics devices need maintenance of firmware and configuration data. The system described here allows this and also long term monitoring of functionality and performance. Both requirements cover measuring devices that operate under a common operating system as well as modules only addressable by means of GPIOs or their programming interface. For large accelerator systems like in the FAIR project, a Web-based remotely controlled system was designed in close collaboration with two industrial partners. To cover the requirements of the extremely different types of participating modules while remaining flexible for future extensions, the system was designed with a maximum of modularity and a strong focus on high reliability and safety. This contribution describes the global structure and the actual status of the RF Maintenance and Diagnostics System. Several types of measuring equipment and LLRF modules such as a phase control loop system and an IF signal pre-processing system have been integrated.

TUPS072

Performance of the Arc Detectors of LHC High Power RF System

radiation, klystron, plasma, ion

1704

D. Valuch, O. Brunner, N. Schwerg
CERN, Geneva, Switzerland

During operation, the LHC high power RF equipment, such as klystrons, circulators, waveguides and couplers have to be protected from damage caused by electromagnetic discharges. Once ignited these arcs grow over the full height of the waveguide and travel towards the RF source. The burning plasma can cause serious damage to the metal surfaces or ferrite materials. The LHC arc detector system is based on the optical detection of the discharge through small apertures in the waveguide walls. The light is guided by means of an optical fibre from the view port to a photo diode. Experience shows that some of the currently used optical fibers suffer from x-ray induced opacity. The sensors are also exposed to the radiation produced by secondary showers coming from the high intensity beams which, if not treated properly, can cause frequent spurious trips. In the second half of the paper we presents a number of improvements to the design. Measurements with optical parameters from real arcs and a fiber-less version of the detector with redundant detectors for critical environments.

TUPS085

Mass Production Report of C-band Choke Mode Accelerating Structure and RF Pulse Compressor

resonance, coupling, acceleration, electron

1737

S. Miura, T. Hashirano, F. Inoue, K. Okihira
MHI, Hiroshima, Japan
T. Inagaki
RIKEN/SPring-8, Hyogo, Japan
H. Maesaka, T. Shintake
RIKEN Spring-8 Harima, Hyogo, Japan

RIKEN and JASRI already completed the construction of XFEL/SPring8. Recently the facility was named “SACLA” (SPring-8 Angstrom Compact Free Electron LAser). The commissioning team succeeded in acceleration of 8 GeV electron beam and observation of the undulator light of 0.8 angstrom wavelength in March 2011. Now the accelerator is stably operated for the XFEL commissioning. In this project, a C-band (5712 MHz) choke mode accelerating structures and C-band RF pulse compressors are employed to obtain a high acceleration gradient of more than 35 MeV/m. We completed the fabrication of 128 accelerating structures, 64 RF pulse compressors, and 64 units of waveguide components and conducted RF measurements on them until May 2010. We report the result of the mass-production of these 64 C-Band units.

TUPS092

Research of Thermal Deformation on a Compact Cyclotron CYCHU-10

cyclotron, vacuum, impedance, radio-frequency

1753

K.F. Liu
HUST, Wuhan, People's Republic of China

Nowadays, a cyclotron CYCHU-10 used for PET is under construction in Huazhong University of Science and Technology (HUST) due to the growing demands in medical applications. For space-saving and low energy consumption, the CYCHU-10 was designed compactly and accurately, especially for the RF cavity consists of the valley of the magnetic pole and the dee electrodes installed on the vacuum chamber. The RF system will supply a 10kw power and large part of it will transform into thermal energy. This paper will introduce the thermal deformation of the RF cavity and the main vacuum chamber. Meanwhile the finite elements analysis thermal deformation with ANSYS Products will be present. Finally, the cooling system for the RF cavity will be carefully designed due to the result of thermo analysis and the mechanical tolerance demand in the RF system. Keywords- thermal deformation; mechanical tolerance; FEA;RF power.

TUPS096

ESS Parameter List Database and Web Interface Tools

linac, lattice, neutron, HOM

1762

K. Rathsman, S. Peggs, P. Reinerfelt, G. Trahern
ESS, Lund, Sweden
J. Bobnar
Cosylab, Ljubljana, Slovenia

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 Accelerator Design Update (ADU) collaboration of mainly European institutions will deliver a Technical Design Report at the end of 2012. To ensure consistency of the information being used amongst all subgroups throughout the period of accelerator design and construction, a parameter list database and web interface have been proposed. The main objective is to provide tools to identify inconsistencies among parameters and to enforce groups as well as individuals to work towards the same solution. Another goal is to make the Parameter Lists a live and credible endeavor so that the data and supporting information shall be useful to a wider audience such as external reviewers as well as being easily accessible.

TUPS098

Machining and Characterizing X-band RF-structures for CLIC

controls, damping, collider, electron

1768

S. Atieh, M. Aicheler, G. Arnau-Izquierdo, A. Cherif, L. Deparis, D. Glaude, L. Remandet, G. Riddone, M. Scheubel
CERN, Geneva, Switzerland
D. Gudkov, A. Samoshkin, A. Solodko
JINR, Dubna, Moscow Region, Russia

The Compact Linear Collider (CLIC) is currently under study at CERN as a potential multi-TeV e+e collider. The manufacturing and assembling tolerances for making the required RF components are essential for CLIC to perform efficiently. Machining techniques are relevant to the construction of ultra-high-precision parts for the Accelerating Structures (AS). Optical-quality turning and ultra-precision milling using diamond tools are the main manufacturing techniques identified to produce ultra-high shape accuracy parts. A shape error of less than 5 micrometres and roughness of Ra 0.025 are achieved. Scanning Electron Microscopy (SEM) observation as well as sub-micron precision Coordinate Measuring Machines (CMM), roughness measurements and their crucial environment were implemented at CERN for quality assurance and further development. This paper focuses on the enhancements of precision machining and characterizing the fabrication of AS parts.

TUPS100

Manufacturing the Linac4 PI-mode Structure Prototype at CERN

linac, vacuum, alignment, controls

1774

G. Favre, A. Cherif, A. Dallocchio, J.-M. Geisser, L. Gentini, F. Gerigk, S.J. Mathot, M. Polini, S. Sgobba, T. Tardy, R. Wegner
CERN, Geneva, Switzerland

The PI-Mode Structure (PIMS) of Linac4 consists of 7-cell cavities made from alternating OFE copper discs and rings welded together with electron beam (EB) welding. A full-scale prototype cavity of almost 1.5 m in length has been manufactured, assembled, and tested at CERN to prepare the series production of 12 PIMS cavities as part of an international collaboration. This paper reports on the construction experience including machining operations, EB welding, vacuum brazing, and metrological measurements results.

TUPS106

Absorber Materials at Room and Cryogenic Temperatures*

HOM, cryogenics, damping, electron

1792

F. Marhauser, T.S. Elliott, A.T. Wu
JLAB, Newport News, Virginia, USA
E.P. Chojnacki
CLASSE, Ithaca, New York, USA
E. Savrun
Sienna Technologies Inc., Woodinville, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.

TUPZ009

LHC Machine Protection against Very Fast Crab Cavity Failures

optics, luminosity, betatron, emittance

1816

T. Baer, R. Tomás, J. Tückmantel, J. Wenninger, F. Zimmermann
CERN, Geneva, Switzerland
T. Baer
Uni HH, Hamburg, Germany
R. Calaga
BNL, Upton, Long Island, New York, USA

For the high-luminosity LHC upgrade program (HL-LHC), the installation of crab cavities (CCs) is essential to compensate the geometric luminosity loss due to the crossing angle. The baseline is a local scheme with CCs around the ATLAS and CMS experiments. In a failure case (e.g. a CC quench), the voltage and/or phase of a CC can change significantly with a fast time constant of the order of a LHC turn. This can lead to large, global betatron oscillations of the beam. Against the background of machine protection, the influence of a CC failure on the beam dynamics is discussed. The results from dedicated tracking studies, including the LHC upgrade optics, are presented. Necessary countermeasures to limit the impact of CC failures to an acceptable level are proposed.

TUPZ038

RHIC Performance for FY2011 Au+Au Heavy Ion Run

luminosity, ion, feedback, heavy-ion

1894

G.J. Marr, L. A. Ahrens, M. Bai, J. Beebe-Wang, I. Blackler, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, J.J. Butler, C. Carlson, R. Connolly, T. D'Ottavio, K.A. Drees, A.V. Fedotov, W. Fischer, W. Fu, C.J. Gardner, D.M. Gassner, J.W. Glenn, X. Gu, M. Harvey, T. Hayes, L.T. Hoff, H. Huang, P.F. Ingrassia, J.P. Jamilkowski, N.A. Kling, M. Lafky, J.S. Laster, C. Liu, Y. Luo, M. Mapes, A. Marusic, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, C. Naylor, S. Nemesure, S. Polizzo, V. Ptitsyn, G. Robert-Demolaize, T. Roser, P. Sampson, J. Sandberg, V. Schoefer, C. Schultheiss, F. Severino, T.C. Shrey, K.S. Smith, D. Steski, S. Tepikian, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, B. Van Kuik, G. Wang, M. Wilinski, A. Zaltsman, K. Zeno, S.Y. Zhang
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.
Following the Fiscal Year (FY) 2010 (Run-10) Relativistic Heavy Ion Collider (RHIC) Au+Au run [1], RHIC experiment upgrades sought to improve detector capabilities. In turn, accelerator improvements were made to improve the luminosity available to the experiments for this run (Run-11). These improvements included: a redesign of the stochastic cooling systems for improved reliability; a relocation of “common” RF cavities to alleviate intensity limits due to beam loading; and an improved usage of feedback systems to control orbit, tune and coupling during energy ramps as well as while colliding at top energy. We present an overview of changes to the Collider and review the performance of the collider with respect to instantaneous and integrated luminosity goals.

WEOAA01

The ThomX Project

laser, injection, feedback, synchrotron

1903

A. Variola
LAL, Orsay, France

Funding: Work supported by the EQUIPEX program, the Ile de France region, CNRS-IN2P3 and Université Paris Sud XI
ThomX is a Compton source project in the range of the hard X rays (40 / 90 keV). The machine is composed of an injector Linac and a storage ring where an electron bunch collides with a laser pulse accumulated in a Fabry-Perot resonator. The final goal is to provide an X-rays average flux of 1011/10¹³ ph/s. The emitted flux will be characterized by a dedicated X-ray line. Different users are partners in the ThomX project, especially in the area of medical science and cultural heritage. Their main goal will be the transfer of all the experimental techniques developed on big synchrotron rings to these more compact and flexible machines. The project ThomX has recently been funded and will be located on the Orsay University campus. In this article the project and its associated scientific interest are presented.

Slides WEOAA01 [5.947 MB]

WEOBA03

Non-scaling Fixed Field Alternating Gradient Permanent Magnet Cancer Therapy Accelerator

acceleration, proton, lattice, permanent-magnet

1923

D. Trbojevic
BNL, Upton, Long Island, New York, USA
V.S. Morozov
JLAB, Newport News, Virginia, USA

Funding: Work performed under U.S. DOE Contract Number DE-AC02-98CH10886.
We present a design of the proton therapy accelerator from 31 MeV to 250 MeV by using racetrack lattice made of Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) arcs and two parallel straight sections. The magnets in the arcs are separated function Halbach type magnets. The dipole bending field is 2.3 T, while the Neodymium Iron Boron magnetic residual induction is Br=1.3 T. The radial orbit offsets in the NS-FFAG arcs, for the kinetic energy range between 31 MeV < Ek < 250 MeV or momentum offset range -50% < δp/p < 50%, are -11.6 mm < x max < 16.8 mm, correspondingly. The straight sections used for the cavities and single turn injection/extraction kickers and septa are with zero orbit offsets. The permanent magnets accelerator should reduce overall and operating cost. It could fit into 8 x 12 m space.

Slides WEOBA03 [2.789 MB]

WEODA03

Design Concepts for the Large Hadron Electron Collider

linac, electron, luminosity, collider

1942

M. Klein
The University of Liverpool, Liverpool, United Kingdom

A report is presented on the design concepts for a high luminosity electron-nucleon collider of 1.3 TeV centre of mass energy, realized with the addition of a 60 GeV electron ring or linear accelerator to the existing proton and ion LHC beam facility, comprising machine magnets, optics, interaction region, cryogenics, rf, civil engineering and further components of the LHeC. The report on behalf of the LHeC study team is a summary of the 2011 LHeC CDR and feedback received from an international review panel.

Slides WEODA03 [9.780 MB]

WEOBB02

Bunch Length Diagnostic with Sub-femtosecond Resolution for High Brightness Electron Beams

laser, undulator, electron, simulation

1967

G. Andonian, E. Hemsing, P. Musumeci, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
A.Y. Murokh
RadiaBeam, Santa Monica, USA
D. Xiang
SLAC, Menlo Park, California, USA

Next generation light sources require electron beams with high peak currents, typically achieved by compression techniques. The temporal diagnosis of these ultra-short beams demands enhanced resolution. We describe a scheme to achieve a temporal resolution on the order of sub-femtoseconds. The scheme is based on encoding the longitudinal profile of the beam on a transverse angular modulation, based on an interaction between the electron beam and a high-power laser in an undulator. This imposes a fast-sweep of the beam, on the order of sub-femtoseconds. A subsequent sweep in the orthogonal dimension by an rf deflecting cavity, imposes a "slow-sweep" on the order of sub-picoseconds. In this paper, we demonstrate applicability of this diagnostic scheme at the BNL ATF and specify the techniques required for practical applicability.

Slides WEOBB02 [1.120 MB]

WEPC003

Low-Beta Empirical Models used in Online Modeling and High Level Applications

space-charge, solenoid, controls, simulation

2001

Y.-C. Chao, G. Goh
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

Using empirically models for elements generated by simulations codes such as Astra in low-beta beamline to provide efficient and more accurate models for machine diagnostic and tuning is discussed. Experience of such application in the framework of XAL may also be presented.

WEPC012

Steering-corrected 88 MHz QWRs for SARAF Phase II

linac, proton, simulation, lattice

2028

J. Rodnizki, J. Ashkenazy, D. Berkovits, Z. Horvitz
Soreq NRC, Yavne, Israel
A. Kolomiets, B. Mustapha, P.N. Ostroumov
ANL, Argonne, USA

Funding: This work is partially supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
SARAF phase II linac is designed for 5 mA 40 MeV proton and deuteron beams. One option is to base the design on Quarter Wave Resonators (QWR). It is suggested to compensate the QWR non-symmetric magnetic field component by introducing a drift tube face tilt angle*. Here we explore the applicability of this steering correction scheme to the acceleration of a CW high current low β light ion beam in an end-to-end 88 MHz QWR lattice. This can serve as a case study for multi-megawatt machines that are currently being designed by ANL. An analytical approximation is used to evaluate the on-axis beam steering behavior. Two 88 MHz QWR cavities, β=0.08 and 0.15, were designed, field and beam dynamics were simulated and optimized. Using the tube face tilt angle concept the beam steering along a QWR can be reduced to the order of 0.1 mrad. Beam dynamics lattice examination including error analysis demonstrated an efficient high performance 40 MeV linac based on 3 superconducting modules with 19 QWRs (Ep < 35 MV/m and Bp < 70 mT). The fields obtained at recent ANL tests for a 73 MHz QWR (70 MV/m and 10⁵ mT) imply that Ep is not a real limiting factor.
* P.N. Ostroumov and K. W. Shepard, PRST-AB 4, 110101 (2001).

WEPC014

Beam Dynamics Simulations of the PIAVE-ALPI Linac

simulation, linac, rfq, diagnostics

2034

M. Comunian, E. Fagotti, F. Grespan, A. Palmieri, A. Pisent, C. Roncolato
INFN/LNL, Legnaro (PD), Italy

At the Legnaro National Laboratories it is operating a SuperConducting linac for nuclear studies. The ALPI linac is injected either by a XTU tandem, up to 14 MV, or by the s-c PIAVE injector, made with 2 SC-RFQ. The main part of the linac (at the present 64 cavities for a total voltage up to 48 MV) is build up in two branches connected by an achromatic and isochronous U-bend. The PIAVE-ALPI complex is able to accelerate beams up to A/q = 7. The layout of the linac ALPI is, from the point of beam dynamics, quite complex due the presence of RFQs, cavities, dipoles, magnets, etc. These elements behaviors are entirely not linear, so a small change on the settings can induce a big change in the Linac beam dynamics. An automatic tuning procedure and a full field maps description are mandatory to handle a so high number of active components. The program used at this scope is TraceWin that is able to do an envelope simulation and a full multiparticles simulation.

WEPC041

Conceptual Design of a New 800 MeV H⁻ Linac for ISIS Megawatt Developments

linac, DTL, quadrupole, rfq

2100

D.C. Plostinar, C.R. Prior, G.H. Rees
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

Several schemes have been proposed to upgrade the ISIS Spallation Neutron Source at Rutherford Appleton Laboratory (RAL). One scenario is to develop a new 800 MeV, H⁻ linac and a ~3 GeV synchrotron, opening the possibility of achieving several MW of beam power. In this paper the design of the 800 MeV linac is outlined. It consists of a 3 MeV Front End similar to the one now under construction at RAL (the Front End Test Stand -FETS). Above 3 MeV, a 324 MHz DTL will be used to accelerate the beam up to ~75 MeV. At this stage a novel collimation system will be added to remove the halo and the far off-momentum particles. To achieve the final energy, a 648 MHz superconducting linac will be employed using three families of elliptical cavities with transition energies at ~196 MeV and ~412 MeV. Alternative designs are also being investigated.

WEPC047

Crab Crossing Schemes and Studies for Electron Ion Collider

electron, collider, lattice, ion

2115

S. Ahmed, S.U. De Silva, Y.S. Derbenev, G.A. Krafft, V.S. Morozov, B.C. Yunn, Y. Zhang
JLAB, Newport News, Virginia, USA
A. Castilla, J.R. Delayen
ODU, Norfolk, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Medium Energy Electron Ion Collider (MEIC) at JLab has been envisioned as future high energy particle accelerator beyond 12 GeV upgrade of CEBAF. Crab crossing of colliding electron and ion beams is essential for accommodating high bunch repetition frequency in the conceptual design of MEIC. The scheme eliminates parasitic beam-beam interactions and avoids luminosity reduction by restoring head-on collisions at interaction points. This requires the separation of two beams quickly to avoid parasitic collisions and the minimization of synchrotron-betatron resonance near IP which can be fulfilled by employing the crab crossing concept first proposed by R. Palmer. Let us call this original scheme as transverse crabbing for the sake of comparison with dispersive crabbing which employs the existing accelerating/bunching RF cavities and dispersion function in the section where the cavity is installed as originally proposed by G. Jackson. In this paper, we report the beam transport and optics for both transverse and dispersive crabbing schemes followed by basic beam dynamics. Moreover, alignment and stability calculations together with synchro-betatron beam dynamics will be discussed.

WEPC051

Effect of Compton Scattering on the Electron Beam Dynamics at the ATF Damping Ring

electron, scattering, laser, damping

2127

I. Chaikovska, C. Bruni, N. Delerue, A. Variola, Z.F. Zomer
LAL, Orsay, France
K. Kubo, T. Naito, T. Omori, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Compton scattering provides one of the most promising scheme to obtain polarized positrons for the next generation of e⁺e⁻ colliders. Moreover it is an attractive method to produce monochromatic high energy polarized gammas for nuclear applications and X-rays for compact light sources. In this framework a four-mirror Fabry-Perot cavity has been installed at the Accelerator Test Facility (ATF - KEK, Tsukuba, Japan) and will be used to produce an intense flux of polarized gamma rays by Compton scattering. For electrons at the energy of the ATF (1.28GeV) Compton scattering may result in a shorter lifetime due to the limited bucket acceptance. We have implemented the effect of Compton scattering on a 2D tracking code with a Monte-Carlo method. This code has been used to study the longitudinal dynamics of the electron beam at the ATF damping ring, in particular the evolution of the energy spread and the bunch length under Compton scattering. The results obtained are presented and discussed. Possible methods to observe the effect of Compton scattering on the ATF beam are proposed.

WEPC067

The Spin Aberration of Polarized Beam in Electrostatic Rings

simulation, emittance, lattice, dipole

2175

Y. Senichev, A. Lehrach, R. Maier, D. Zyuzin
FZJ, Jülich, Germany

For a beam with nonzero transverse emittance and momentum spread passing through an electric field, for example an electric focusing lens or deflector, the orientation of a spin vector becomes a function of 6D initial phase coordinates that leads to spin aberrations. We investigate this process analytically and numerically.

WEPC087

Dark Current Simulations for the Cornell ERL

linac, electron, simulation, cryomodule

2214

C.E. Mayes, C.S. Chiu, G.H. Hoffstaetter, V.O. Kostroun, D. Sagan
CLASSE, Ithaca, New York, USA
L.M. Nash
North Carolina University, Chapel Hill, North Carolina, USA

Funding: Supported by NSF award DMR-0807731
Charged particles unintentionally transported through an accelerator, collectively called the dark current, can be lost in the beam chamber and create a radiation hazard for both equipment and personnel. Here we simulate the creation of particles by field emission in the superconducting accelerating cavities of the Cornell Energy Recovery Linac, and track them to their loss points. These lost particles can then be used to simulate background radiation. The presented calculations are therefore an essential step in the design of appropriate radiation-shielding of components around the linac.

WEPC092

Moment-Based Simulation of the S-DALINAC Recirculations*

simulation, recirculation, linac, quadrupole

2223

S. Franke, W. Ackermann, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
R. Eichhorn, F. Hug, C. Klose, N. Pietralla, M. Platz
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG under contract SFB 634.
The Superconducting Linear Accelerator S-DALINAC installed at the institute of nuclear physics (IKP) at TU Darmstadt is designed as a re-circulating linear accelerator. The length of the beam line and the numerous accelerating structures as well as dipole and quadrupole magnets require a highly efficient numerical simulation tool in order to assist the operators by providing a detailed and almost instantaneous insight into the actual machine status. A suitable approach which enables a fast online calculation of the beam dynamics is given by the so-called moment approach where the particle distribution is represented by means of a discrete set of moments or by multiple discrete sets of moments in a multi-ensemble environment. Following this approach the V-Code simulation tool has been implemented at the Computational Electromagnetics Laboratory (TEMF) at TU Darmstadt. In this contribution an overview of the numerical model is presented together with new V-Code simulation results regarding the S-DALINAC recirculation sections.

WEPC093

Various Approaches to Electromagnetic Field Simulations for RF Cavities

simulation, impedance, HOM, higher-order-mode

2226

C. Liu, W. Ackermann, W.F.O. Müller, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Work supported by BMBF under contract 05H09RD5
In the Superconducting Proton Linac (SPL) cavity, there is not only the fundamental mode for the particle acceleration but also many higher order modes (HOMs), which can lead to particle beam instabilities. This is very dangerous for SPL cavity. Therefore it is necessary to simulate the electromagnetic field in the SPL cavity, so that the field distribution and the shunt impedance for every higher order mode can be precisely calculated. At TEMF this research work can be done in three different ways: field simulation with hexahedron mesh in frequency domain, field simulation with hexahedron mesh in time domain and field simulation with tetrahedral mesh and higher order curvilinear elements. Finally the HOM coupler will be considered for the effective damping of higher order modes in the SPL cavity.

WEPC096

Calculation of High Frequency Fields in Resonant Cavities Based on Perturbation Theory*

superconducting-cavity

2235

K. Brackebusch, H.-W. Glock, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: Work supported by Federal Ministry for Research and Education BMBF under contracts 05H09HR5 and 05K10HRC.
The knowledge of the eigenmodes of resonant accelerator cavities is essential for the determination of their performance characteristics, comprising resonant frequencies and field distributions inside the cavities. Apart from the material properties the eigenmodes of a cavity depend on its geometry. In spite of the high elaborateness during the complex fabrication process, minor deviations of the actual cavity shape from the desired one are inevitable. Moreover, especially superconducting cavities are subject to extreme operating conditions that may cause deformations of their shape. Any geometry perturbation results in a shift of the resonant frequencies and modified field distributions. In this paper, we will analyze a generalization of Slater's theorem proposed in literature. The method should allow for the calculation of resonant frequencies and field distributions of a slightly perturbed cavity by using a set of precomputed eigenmodes of the unperturbed cavity. We will evaluate the practicability of the method by applying it to cavity geometries for which the eigenmodes are analytically known, ascertain the effort of reasonable calculation results and describe its limitations.

WEPC097

A Concatenation Scheme for the Computation of Beam Excited Higher Order Mode Port Signals

HOM, wakefield, coupling, higher-order-mode

2238

T. Flisgen, H.-W. Glock, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Ongoing studies investigate in how far higher order mode (HOM) port signals of superconducting RF cavities can be used for machine and beam diagnostics. Apart from experiments e.g. at the FLASH facility at DESY in Hamburg, numerical modelling is needed for the prediction of HOM coupler signals. For this purpose, the RF properties of the entire accelerating module have to be taken into account, since higher order modes can propagate along the cavity chain. A discretization of the full chain, followed by a wake field simulation is only feasible with powerful and expensive cluster computers. Instead, an element wise wake field simulation of sub-sections of the chain, followed by a suitable concatenation scheme can be performed on standard hardware assuming the beam to be sufficiently stiff. In this paper a concatenation scheme for the computation of beam excited HOM port signals is derived as a generalization of the Coupled S-Parameter scheme CSC. Furthermore, the validity of the method is shown for a sample structure.

WEPC098

Automatic Pole and Q-Value Extraction for RF Structures

resonance, scattering, RF-structure, cryomodule

2241

C. Potratz, H.-W. Glock, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
F. Marhauser
JLAB, Newport News, Virginia, USA

The experimental characterization of RF structures like accelerating cavities often demands for measuring resonant frequencies of Eigenmodes and corresponding (loaded) Q-values over a wide spectral range. A common procedure to determine the Q-values is the -3dB method, which works well for isolated poles, but may not be applicable directly in case of multiple poles residing in close proximity (e.g. for adjacent transverse modes differing by polarization). Although alternative methods may be used in such cases, this often comes at the expense of inherent systematic errors. We have developed an automation algorithm, which not only speeds up the measurement time significantly, but is also able to extract Eigenfrequencies and Q-values both for well isolated and overlapping poles. At the same time the measurement accuracy may be improved as a major benefit. To utilize this procedure merely complex scattering parameters have to be recorded for the spectral range of interest. In this paper we present the proposed algorithm applied to experimental data recorded for superconducting higher-order-mode damped multi-cell cavities as an application of high importance.

WEPC107

Development of a Steady State Simulation Code for Klystron Amplifiers

space-charge, simulation, klystron, electromagnetic-fields

2265

C. Marrelli
CERN, Geneva, Switzerland
M. Migliorati, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
B. Spataro
INFN/LNF, Frascati (Roma), Italy
S.G. Tantawi
SLAC, Menlo Park, California, USA

The design of klystrons is based on the intensive utilization of simulation codes, which can evaluate the complete beam-cavities interaction in the case of large signals. In the present work, we present the development of a 2-D steady state simulation code that can self-consistently evaluate the effects of the electromagnetic field on the particles and of the particles back on the field. The algorithm is based on the iterative solution of the power balance equation in the RF structures and allows determining the amplitude and phase of the electromagnetic field starting from the cavity modes. Some applications of the code to a single cavity and a two cavity klystron are presented and compared with the results obtained from other codes. The effect of the space charge forces in the klystron drift tubes is also evaluated.

WEPC111

Single Particle Tracking Simulation for Compact Cyclotron*

simulation, cyclotron, positron, injection

2274

H.W. Kim, J.-S. Chai, B.N. Lee, Y.S. Lee, K.R. Nam, H.S. Song
SKKU, Suwon, Republic of Korea

Funding: Ministry of Education, Science and Technology, Republic of Korea. Department of Energy Science and School of Information and Communication Engineering of SungKyunKwan University.
Low energy compact cyclotrons for Positron emission tomography (PET) are needed for the production of radio-isotope. In the magnet design for those cyclotrons, single particle tracking simulation after the design is important to check the quality of designed magnetic field of the magnet. The study of single particle tracking simulation for cyclotron magnet is shown in this paper. Maximum beam energy of example cyclotron is 9 MeV for proton and pseudo accelerating gap is adapted for the simulation. 3D CAD program CATIA P3 V5 R18 is used for design the magnet and pseudo accelerating gap. All magnetic and electric field calculations had been performed by OPERA-3D TOSCA and the own-made program OPTICY is used for other calculations - phase slip, radial and axial tune.

WEPC125

Higher Order Modes in Coupled Cavities of the FLASH Module ACC39

simulation, HOM, diagnostics, dipole

2301

R.M. Jones, I.R.R. Shinton
UMAN, Manchester, United Kingdom
Z. Li
SLAC, Menlo Park, California, USA

We analyse the higher order modes (HOMs) in the 3.9GHz bunch shaping cavities installed in the FLASH facility at DESY. A suite of finite element computer codes (including HFSS and ACE3P) and globalised scattering matrix calculations are used to investigate the modes in these cavities. This study is primarily focused on the dipole component of the multiband expansion of the wakefield, with the emphasis being on the development of a HOM-based BPM system for ACC39. Coupled inter-cavity modes are simulated together with a limited band of trapped modes.

WEPC144

Beam Monitor Deformation by Tohoku Earthquake and its Recovery Project

vacuum, linac, DTL, impedance

2328

A. Miura, K. Hasegawa, H. Oguri, N. Ouchi
JAEA/J-PARC, Tokai-mura, Japan
Z. Igarashi, M. Ikegami, T. Miyao
KEK, Ibaraki, Japan

On March 11, 2011, the biggest earthquake occurred at Tohoku and North Kanto area in Japan. This earthquake and related ones have attacked J-PARC accelerators and caused the big damage. As for the linac beam monitors, some commissioning tools which were installed in the linac had damage and the air leakage was observed. In the first step of the recovery work, we checked the damage and put the emergency treatment for vacuum of the cavities. All beam monitors were observed, the leak from the vacuum devices was tested and the conduction of the signal cables was measured to compare the previous performance. In the next step, we started to order the new devices which should be replaced and to obtain the calibration data. We found the leakage from the phase monitors. The earthquake caused the crack and deformation at the welded points between the metallic parts and ceramic parts. And a wire of the profile monitor was broken while the beam position monitors have no damage. We are continuing this recovery work ongoingly.

WEPC145

Progress in Developing a PLC Control System for the PKUNIFTY

controls, pick-up, rfq, neutron

2331

J. Zhao, J.E. Chen, Z.Y. Guo, Y.R. Lu, S.X. Peng, Q.F. Zhou
PKU/IHIP, Beijing, People's Republic of China

A compact remote PLC control system has been developed for the PKUNIFTY (Peking University Neutron Imaging FaciliTY). That facility is based on a 2 MeV deuteron RFQ accelerator. The PLC control system has been successfully used for the injector including ECR ion source and LEBT, and it worked reliably last year. Now the control of RFQ cavity, HEBT and Be target has been completed and tested. The interlock system has been enhanced. A low level RF control system, including the auto frequency control (AFC) and auto gain control (AGC) circuits, has been designed for the RFQ’s RF power system. Those circuits will work as a lower controller of the PLC control system. The main running parameters can be controlled by setting any desired range of values on the HMI. Test results of hardware and software are presented.

WEPO028

Design of HTS Sector Magnets for the RCNP New Injector Cyclotron

cyclotron, dipole, injection, neutron

2460

K. Hatanaka, M. Fukuda, N. Izumi, M. Kibayashi, S. Morinobu, K. Nagayama, T. Saito, H. Tamura, H. Ueda, Y. Yasuda, T. Yorita
RCNP, Osaka, Japan
T. Kawaguchi
KT Science Ltd., Akashi, Japan

The RCNP cyclotron cascade system consists of K140 AVF cyclotron and K400 ring cyclotron and is providing high quality beams for various experiments. There are increasing demands for high intensity beams and even to improve the quality. In order to increase the physics research opportunities, a new injector cyclotron is recently proposed, which has four separated sector magnets and two accelerating cavities. Sector magnets are designed to use High Temperature Superconducting (HTS) wire. At RCNP we have been developing magnets with HTS wires for a decade. In this paper, we will report recent results of developed HTS magnets and the design of sector magnets for the new injector SSC.

WEPO030

Fabrication and Testing of the First Magnet Package Prototype for the SRF Linac of LIPAc

solenoid, linac, SRF, vacuum

2463

S. Sanz, J. Calero, F.M. De Aragon, J.L. Gutiérrez, I. Moya, I. Podadera, F. Toral, J.G.S. de la Gama
CIEMAT, Madrid, Spain
N. Bazin, P. Bosland, P. Bredy, N. Grouas, P. Hardy, V.M. Hennion, J. Migne, F. Orsini, B. Renard
CEA/DSM/IRFU, France
G. Disset, J. Relland
CEA, Gif-sur-Yvette, France
H. Jenhani
CEA/IRFU, Gif-sur-Yvette, France
E.N. Zaplatin
FZJ, Jülich, Germany

Funding: Work partially supported by Spanish Ministry of Science and Innovation under project AIC10-A-000441 and ENE2009-11230.
The IFMIF-EVEDA accelerator will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology that will be used in the future IFMIF accelerator. The SRF Linac design is based on superconducting Half Wave Resonators (HWR) cavities operating at 4.4 K. Due to space charge associated to the high intensity beam, a short, but strong, superconducting focusing magnet package is necessary between cavities. The selected configuration has been a superconducting NbTi solenoid acting as a magnetic lens and a concentric outer solenoid in antiparallel configuration to reduce the dangerous stray field on the cavities. The selected arrangement for the steerers is a pair of parallel racetrack coils for each vertical and horizontal axis. This paper describes the manufacturing techniques of the different coils, and the test realized in warm and cold conditions, with special attention to the training test of the main solenoid, as the nominal working point in the load line is very high (86.2%).

WEPO035

Thermal Performance of the S1-Global Cryomodule for ILC

cryomodule, radiation, linac, vacuum

2472

N. Ohuchi, M. Akemoto, S. Fukuda, K. Hara, H. Hayano, N. Higashi, E. Kako, Y. Kojima, Y. Kondo, T. Matsumoto, S. Michizono, T. Miura, H. Nakai, H. Nakajima, K. Nakanishi, S. Noguchi, T. Saeki, M. Satoh, T. Shidara, T. Shishido, T. Takenaka, A. Terashima, N. Toge, K. Tsuchiya, K. Watanabe, S. Yamaguchi, A. Yamamoto, Y. Yamamoto, K. Yokoya
KEK, Ibaraki, Japan
T.T. Arkan, S. Barbanotti, H. Carter, M.S. Champion, A. Hocker, R.D. Kephart, J.S. Kerby, D.V. Mitchell, T.J. Peterson, Y.M. Pischalnikov, M.C. Ross
Fermilab, Batavia, USA
A. Bosotti, C. Pagani, R. Paparella, P. Pierini
INFN/LASA, Segrate (MI), Italy
D. Kostin, L. Lilje, A. Matheisen, W.-D. Möller, N.J. Walker, H. Weise
DESY, Hamburg, Germany

The S1-Global program is the international research collaboration among INFN, FNAL, DESY, SLAC and KEK as one of the GDE R&D for construction of ILC. The S1-Global cryomodule consists of two half-size cryomodules of 6 meter. One was designed by IFNF, and it contained two FNAL cavities and two DESY cavities. The associated components, like input couplers and RF cables, were same as the TTF-III cryomodule. The other was designed by KEK, and the thermal design was based on the TTF-III cryomodule. This cryomodule contains four KEK cavities with the associated components which were designed by KEK. For characterizing the thermal performances of two cryomodules, the static heat load and the temperature profiles of the cold components were measured. The temperature profiles of the components were compared between two cryomodules and the static heat load was evaluated with the design values of the cryomodules. The dynamic losses of the DESY, FNAL and two KEK cavities at their maximum operative gradients were measured and, with the measured losses, Q values were calculated. In this paper, we will make the summary of the thermal measurements of the S1-Global cryomodule.

WEPO036

Design of a Cryogenic Regulation Valve Box for SRF Operation at TPS

SRF, cryogenics, feedback, coupling

2475

M.H. Chang, L.-H. Chang, L.J. Chen, F.-T. Chung, F. Z. Hsiao, M.-C. Lin, Y.-H. Lin, C.H. Lo, H.H. Tsai, Ch. Wang, T.-T. Yang, M.-S. Yeh, T.-C. Yu
NSRRC, Hsinchu, Taiwan
L.L. Han, M.H. Tsai
NTUT, Taiwan

A 3-GeV light source named Taiwan Photon Source (TPS) at National Synchrotron Radiation Research Center (NSRRC) is under construction, and is scheduled for commissioning in 2013/2014. An SRF module of KEKB type has been selected for the TPS as the accelerating cavity of its storage ring. The SRF valve boxes, as part of the cryogenic transfer system, stabilize the cryogenic operational conditions required for various needs of SRF operation. The SRF operation requires a large dynamic variation in the cryogenic loading that challenges appropriate sizing of the cryogenic regulation valves to minimize the pressure drop and concurrently to maintain a fine regulation of pressure. Here, we report our design considerations for an SRF valve box with emphasis on highly stabilizing the helium pressure for SRF operation with a dual-return valve scheme. The estimated fluctuations of pressure due to finite accuracy of the valve opening decrease to a tenth of what is obtained from the conventional single return-valve scheme.

WEPS006

CNAO RF System: Hardware Description.

proton, resonance, controls, impedance

2493

L. Falbo, G. Burato
CNAO Foundation, Milan, Italy
M.M. Paoluzzi, G. Primadei
CERN, Geneva, Switzerland

CNAO is the Italian National Center of Oncological Hadrontherapy in Pavia. Proton beams are accelerated in the synchrotron and extracted in the energy range 60 to 250 MeV/u and carbon ion beams in the energy range 120 to 400 MeV/u. Trapping at the injection energy of 7 MeV/u and acceleration up to the extraction energy are done by an RF cavity which covers the needed wide range of frequency (0.4 to 3 MHz) and voltage (25 V to 5 kV) thanks to the use of a Vitrovac amorphous alloy. RF Gymnastics, including phase jumps to increase the momentum spread and empty bucket channelling, is requested and has been performed. A description of the hardware characteristics of the CNAO RF system and of its performance in terms of dynamic and static behaviour are reported in this paper.

WEPS010

Acceleration of High Intensity Proton Beams in the J-PARC Synchrotrons

impedance, injection, acceleration, synchrotron

2502

M. Yoshii
KEK/JAEA, Ibaraki-Ken, Japan
E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, K. Takata, M. Toda
KEK, Ibaraki, Japan
T. Minamikawa
University of Fukui, Fukui, Japan
M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan

The J-PARC accelerator complex consists of the linac, the 3GeV rapid cycling synchrotron (RCS) and the 50GeV main synchrotron (MR). These synchrotrons are the first MW-class proton accelerators which employ the high electric field gradient magnetic alloy (MA) loaded RF cavities. The beam commissioning was started in October 2007 for RCS and in May 2008 for MR. High intensity beam operation studies and user runs have been performed, while carefully controlling and minimizing the beam loss. The cycle to cycle beam operation is reproducible and quite stable, because of the stable linac beam energy and the reproducible bending field in both synchrotrons. The MA loaded RF systems and the full digital LLRF also guarantee the stable longitudinal particle motion and precise beam transfer synchronization from RCS to the MLF user facility as well as to the MR. A high intensity proton beam of 2.5·10¹³ ppp is accelerated in RCS. And in MR, a beam intensity up to ~100 Tera ppp was obtained.　We summarize the RF systems and the longitudinal parameters in both rings.

WEPS014

RF Systems and Bunch Formation at NICA

collider, ion, booster, injection

2511

A.V. Eliseev, I.N. Meshkov, A.O. Sidorin, G.V. Trubnikov
JINR, Dubna, Moscow Region, Russia
O.I. Brovko
JINR/VBLHEP, Moscow, Russia
G.Y. Kurkin, V.M. Petrov
BINP SB RAS, Novosibirsk, Russia

The NICA facility being constructed at JINR will consists of two synchrotrons (Booster and Nuclotron) and collider working at constant magnetic field. To reach required luminosity level the collider rings will be operated with short ion bunches. The bunch formation in the collider as well as longitudinal dynamics in all the rings is described. The parameters and preliminary design of RF systems are presented.

WEPS018

The Proposed CERN Proton-Synchrotron Upgrade Program

injection, emittance, space-charge, electron

2520

S.S. Gilardoni, S. Bart Pedersen, W. Bartmann, S. Bartolome, O.E. Berrig, C. Bertone, A. Blas, D. Bodart, J. Borburgh, R.J. Brown, A.C. Butterworth, M.C.L. Buzio, C. Carli, P. Chiggiato, H. Damerau, T. Dobers, R. Folch, R. Garoby, B. Goddard, M. Gourber-Pace, S. Hancock, M. Hourican, P. Le Roux, L.A. Lopez Hernandez, A. Masi, G. Metral, Y. Muttoni, E. Métral, M. Nonis, J. Pierlot, S. Pittet, C. Rossi, I. Ruehl, G. Rumolo, L. Sermeus, R.R. Steerenberg, M. Widorski
CERN, Geneva, Switzerland

In the framework of the High-Luminosity LHC project, the CERN Proton Synchrotron would require a major upgrade to match the future beam parameters requested as pre-injector of the collider. The different beam dynamics issues, from space-charge limitations to longitudinal instabilities are discussed, as well as the proposed technical solutions to overcome them, covering the increase of the injection energy to RF related improvements.

WEPS023

A Possible RF System for CERN RCS

synchrotron, injection, extraction, booster

2532

M.M. Paoluzzi
CERN, Geneva, Switzerland

As part of the LHC Injectors Upgrade (LIU) program at CERN the possibility of replacing the PSB with a new Rapid Cycling Synchrotron (RCS) is considered. The requirements in terms of accelerating voltage (60 kV), frequency range (1.7 MHz – 9.5 MHz) and available space (4 m) make the RF system development quite challenging. The improved loss characteristics of the new FINEMET® type (FT3L) combined with a filter-like topology, allows achieving all the requirements. This paper describes the design of such a RF system.

WEPS025

First Beam Experiments at ISIS with a Low Output-impedance Second Harmonic Cavity

impedance, simulation, proton, synchrotron

2538

Y. Irie, S. Fukumoto, K. Muto, H. Nakanishi, T. Oki, A. Takagi
KEK, Ibaraki, Japan
D. Bayley, I.S.K. Gardner, R.J. Mathieson, A. Seville, J.W.G. Thomason
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
J.C. Dooling, D. Horan, R. Kustom
ANL, Argonne, USA
M.E. Middendorf
ORNL RAD, Oak Ridge, Tennessee, USA

A Low Output-Impedance (LOI) rf drive, which may be suitable for future high intensity accelerator applications, has been developed jointly by ANL, ISIS and KEK for an ISIS synchrotron second harmonic cavity. The cavity is ferrite-loaded, and is driven by a high-power triode (240 kW plate dissipation) with a plate-to-grid feedback circuit. The impedance is designed to be 20~30 ohms over a 2-6 MHz frequency range. Beam induced voltage has been measured with the ISIS beam, and compared with that calculated from the designed output impedance.

WEPS031

Future Heavy Ion Linacs at GSI

linac, ion, rfq, heavy-ion

2550

W.A. Barth, G. Clemente, L.A. Dahl, S. Mickat, B. Schlitt, W. Vinzenz
GSI, Darmstadt, Germany

The UNILAC-upgrade program for FAIR will be realized in the next three years; the required U²⁸⁺-beam intensity of 15 emA (for SIS 18 injection). The replacement of the Alvarez-DTL by a new high energy linac is advised to provide a stable operation for the next decades. An additional linac-upgrade option sufficient to boost the beam energy up to 150 MeV/u may help to reach the desired heavy ion intensities in the SIS 100. The SHIP-upgrade program has also to be realized until 2011, such that an enhanced primary beam intensity at the target is available. It is planned to build a new cw-heavy ion-linac behind the present high charge state injector. This linac should feed the GSI flagship experiments SHIP and TASCA, as well as material research, biophysics and plasma physics experiments in the MeV/u-area. The whole injector family is housed by the existing constructions. Different layout scenarios of a multipurpose high intensity heavy ion facility will be presented.

WEPS032

Conceptual Study for the New HE-Linac at GSI

linac, injection, DTL, acceleration

2553

G. Clemente, W.A. Barth, B. Schlitt
GSI, Darmstadt, Germany

The commissioning of the first three modules of the FAIR accelerator facility is planned to be completed in 2016. At that time the DTL section of the UNILAC will be more than 40 years old. Different proposals for a new high intensity, heavy ion linac which will replace the ALVAREZ DTL as synchrotron injector are under discussion. This new High Energy-UNILAC will be design accordingly to the advanced FAIR requirements and will allow for complete and reliable multi-ion-operation for at least the next 30 years. In a first step it is foreseen to replace the first two DTL cavity, up to 4.7 AMeV. 4 IH cavities will be used to accelerate U⁴⁺ to 3 AMeV and, after gas stripping, another cavity will provide the second step of acceleration for U³⁸⁺ to 4.77 AMeV. For the next upgrade different options concerning the injection energy are under investigation. The main target is to provide a higher charge state and a higher injection energy to increase the life time of the heavy ion beam inside the synchrotron. The paper presents the beam dynamics and RF investigation for the first upgrade together with a conceptual study design for the complete replacement of the GSI ALVAREZ DTL.

WEPS036

First Coupled CH Power Cavity for the FAIR Proton Injector

coupling, linac, proton, DTL

2565

R. M. Brodhage, C. Fix, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
G. Clemente, L. Groening
GSI, Darmstadt, Germany

For the research program with cooled antiprotons at FAIR a dedicated 70 MeV, 70 mA proton injector is required. The main acceleration of this room temperature linac will be provided by six CH cavities operated at 325 MHz. Each cavity will be powered by a 2.5 MW Klystron. For the second acceleration unit from 11.5 MeV to 24.2 MeV a 1:2 scaled model has been built. Low level RF measurements have been performed to determine the main parameters and to prove the concept of coupled CH cavities. For this second tank technical and mechanical investigations have been performed in 2010 to develop a complete technical concept for the manufacturing. In Spring 2011, the construction of the first power prototype has started. The main components of this cavity will be ready for measurements in summer 2011. At that time, the cavity will be tested with a preliminary aluminum drift tube structure, which will allow precise frequency and field tuning. This paper will report on the recent technical development and achievements. It will outline the main fabrication steps towards that novel type of proton DTL. Also first low level RF measurements are expected.

WEPS038

Development of CH-Cavities for the 17 MeV MYRRHA-Injector

proton, DTL, acceleration, rfq

2571

D. Mäder, H. Klein, H. Podlech, U. Ratzinger, M. Vossberg, C. Zhang
IAP, Frankfurt am Main, Germany

Funding: European Union FP7 MAX Contract Number 269565
MYRRHA is conceived as an accelerator driven system (ADS) for transmutation of high level nuclear waste. The neutron source is created by coupling a proton accelerator of 600 MeV with a 4 mA proton beam, a spallation source and a sub-critical core. The IAP of Frankfurt University is responsible for the development of the 17 MeV injector operated at 176 MHz. The injector consists of a 1.5 MeV 4-Rod-RFQ and six CH-drifttube-structures. The first two CH-structures will be operated at room temperature and the other CH-structures are superconducting cavities assembled in one cryo-module. To achieve the extremely high reliability required by the ADS application, the design of the 17 MeV injector has been intensively studied, with respect to thermal issues, minimum peak fields and field distribution.

WEPS039

General Layout of the 17 MeV Injector for MYRRHA

rfq, linac, proton, ECR

2574

H. Podlech, M. Busch, F.D. Dziuba, H. Klein, D. Mäder, U. Ratzinger, A. Schempp, R. Tiede, C. Zhang
IAP, Frankfurt am Main, Germany
M. Amberg
HIM, Mainz, Germany

Funding: European Union FP7 MAX Contract Number 269565
The MYRRHA Project (Multi Purpose Hybrid Reactor for High Tech Applications) at Mol/belgium will be a user facility with emphasis on research with neutron generated by a spallation source. One main aspect is the demonstration of nuclear waste technology using an accelerator driven system. A superconducting linac delivers a 4 mA, 600 MeV proton beam. The first accelerating section is covered by the 17 MeV injector. It consists of a proton source, an RFQ, two room temperature CH cavities and 4 superconducting CH-cavities. The initial design has used an RF frequency of 352 MHz. Recently the frequency of the injector has been set to 176 MHz. The main reason is the possible use of a 4-rod-RFQ with reduced power dissipation and energy, respectively. The status of the overall injector layout including cavity design is presented.

Poster WEPS039 [2.281 MB]

WEPS040

The Driver Linac of the Neutron Source FRANZ

proton, rfq, neutron, DTL

2577

U. Ratzinger, B. Basten, L.P. Chau, H. Dinter, M. Droba, M. Heilmann, M. Lotz, O. Meusel, I. Müller, D. Mäder, Y.C. Nie, D. Noll, H. Podlech, A. Schempp, W. Schweizer, K. Volk, C. Wiesner, C. Zhang
IAP, Frankfurt am Main, Germany

FRANZ is under construction at the Goethe University Frankfurt. A 2MeV ± 100 keV proton beam will produce 1 keV to 200 keV neutrons on a Li7 target. Experiments are planned in the field of nuclear astrophysics as well as in applied physics. A dc operated proton source with a maximum beam current of 200 mA was successfully beam tested end of 2010. FRANZ will have two experimental areas: One for activation experiments with cw proton beams of a few mA generating a usable neutron flux of some 10 billion per square cm per second, the other one for 250 kHz, 1 ns short neutron bunches generated by 1 ns proton pulses of a few Ampere beam current. A special 2 MeV, 175 MHz high current cavity is realized at present as a RFQ-DTL combination. Novel techniques have been invented to reach the needed pulsed target beam current by a bunch compressor system.
Work supported by HICforFAIR and GSI.

WEPS043

From EUROTRANS to MAX: New Strategies and Approaches for the Injector Development

rfq, DTL, linac, emittance

2583

C. Zhang, H. Klein, D. Mäder, H. Podlech, U. Ratzinger, A. Schempp, R. Tiede
IAP, Frankfurt am Main, Germany

Funding: The research leading to these results has received funding from the European Atomic Energy Community’s (Euratom) Seventh Framework Programme FP7/2007-2011 under grant agreement n° [269565].
As the successor of the EUROTRANS project, the MAX project is aiming to continue the R&D effects for a European Accelerator-Driven System and to bring the conceptual design to reality. The layout of the driver linac for MAX will follow the reference design made for the XT-ADS phase of the EUROTRANS project. For the injector part, new design strategies and approaches, e.g. half resonant frequency, half transition-energy between the RFQ and the CH-DTL, and using the 4-rod RFQ structure instead of the originally proposed 4-vane RFQ, have been conceived and studied to reach a more reliable CW operation at reduced costs. In this paper, the design and simulation results of the MAX injector are presented.

WEPS045

Feasibility Study of a High-gradient Linac for Hadrontherapy

linac, ion, cyclotron, accelerating-gradient

2589

S. Verdú-Andrés, U. Amaldi, A. Degiovanni
TERA, Novara, Italy
A. Faus-Golfe, S. Verdú-Andrés
IFIC, Valencia, Spain
P.A. Posocco
CERN, Geneva, Switzerland

Funding: The research leading to this results has been funded by the Seventh Framework Program [FP7/2007-2013] under grant agreement number 215840-2.
Compact, reliable and little consuming accelerators are needed for tumor treatment with hadrons. As solution, TERA proposes CABOTO (CArbon BOoster for Therapy in Oncology), a linac which boosts the energy of carbon ions and H₂ molecules coming from a cyclotron. The linac, typically a Side-Coupled Linac (SCL), is divided into several modules. The beam energy can be varied in steps of about 15 MeV/u without using absorbers by acting on the power (amplitude and/or phase) that feeds the different modules of the linac. This work presents the structure design of a 5.7 GHz high repetition rate SCL for a cyclinac, that accelerates carbon ions from 150 up to 400 MeV/u in less than 25 meters. The beam dynamics for this linac and its particular energy selection system is also discussed for different beam energy outputs.

WEPS046

Longitudinal Beam Acceptance of J-PARC Drift Tube Linac

DTL, beam-losses, linac, simulation

2592

T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
KEK, Ibaraki, Japan
A. Miura, G.H. Wei
JAEA/J-PARC, Tokai-mura, Japan
H. Sako
JAEA, Ibaraki-ken, Japan

The longitudinal acceptance of the J-PARC Drift Tube Linac (DTL) was measured by synchronous phase scan method. The IMPACT simulation indicated DTL longitudinal acceptance is shrinked if the DTL tank level reduced, but beam energy finally acheved at the Linac is almost same as the case of nominal tank level. We measured the acceptance and confirmed the simulation is correct.

WEPS049

Floor Deformation of J-PARC Linac after the Tohoku Earthquake in Japan

linac, alignment, DTL, injection

2601

T. Morishita, H. Asano
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
M. Ikegami
KEK, Ibaraki, Japan

J-PARC linac has finalized its precise alignment at the end of summer 2006, and the beam provision to the Rapid Cycling Synchrotron has been started at Sept. 2007. Since then, the deformation of the accelerator tunnel is small enough to keep the soundness of the alignment accuracy. Therefore, the linac has been operated without realignment of the accelerator components for these four years. However, the alignment has seriously been damaged due to the large earthquake at Mar. 11th, 2011 in eastern Japan. Now, work for restoration is being continued. In this paper, the deformation of the linac tunnel floor due to the earthquake is reported. Since then, aftershock happens frequently. We also report the stability of the tunnel floor.

WEPS050

The MEBT Design for the China Accelerator Driven System

emittance, rfq, diagnostics, quadrupole

2604

H. Geng, H.F. Ouyang, J. Tang
IHEP Beijing, Beijing, People's Republic of China
Z. Li, S. Pei, F. Yan
IHEP Beijng, Beijing, People's Republic of China

The Medium Eneryg Beam Transport (MEBT) line plays an important role in transporting and matching the beam from the RFQ exit to the entrance to the next type of acceleration structures while provides enough beam diagnostics for beam commissing and tuning. The beam dynamics design for the 1GeV China Accelerator Driven System (CADS) is making great progress. In this paper, we will describe the design–both element choosing and beam dynamics study of the 3MeV MEBT for the CADS project.

WEPS054

The Comparison of ADS Injector II with HWR Cavity and CH Cavity

linac, proton, emittance, simulation

2616

Z.J. Wang, Y. He
IMP, Lanzhou, People's Republic of China

High current superconducting proton linac is being studied for Accelerator-driven System (ADS) Project hold by the Chinese Academic of Sciences (CAS). The injector II, which will accelerate proton beam from 2.1 MeV to 10 MeV, will be operated with superconducting cavity. At low energy part, there are two alternative choose, one is HWR cavity, the other is CH cavity. In this paper, the comparison of design with the two type cavities will be presented in view of beam dynamics.

WEPS058

The Medium Energy Beam Transport Line (MEBT) of IFMIF/EVEDA LIPAc

rfq, SRF, vacuum, quadrupole

2628

I. Podadera, J.C. Calvo, J.M. Carmona, A. Ibarra, D. Iglesias, A. Lara, C. Oliver, F. Toral
CIEMAT, Madrid, Spain

Funding: Work partially supported by Spanish Ministry of Science and Innovation under project AIC10-A-000441 and ENE2009-11230.
The IFMIF-EVEDA Linear IFMIF Prototype Accelerator (LIPAc)will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology that will be used in the future IFMIF accelerator. The acceleration of the beam will be carried out in two stages. An RFQ will increase the energy up to 5 MeV before a Superconducting RF (SRF) linac made of a chain of eight Half Wave Resonators bring the particles to the final energy. Between both stages, a Medium Energy Beam Transport line (MEBT) is in charge of transporting and matching the beam between the RFQ and the SRF. The transverse focusing of the beam is controlled by five quadrupole magnets with integrated steerers, grouped in one triplet and one doublet. Two buncher cavities surrounding the doublet handle the longitudinal dynamics. Two movable collimators are also included to purify the beam optics coming out the RFQ and avoid losses in the SRF. From the inputs of the beam dynamics group, CIEMAT is in charge of designing, manufacturing and integrating all the components of the beamline. In this contribution, the MEBT subsystem will be described and the main objectives and issues for each component will be discussed.

WEPS059

Layout of the ESS Linac

linac, cryomodule, proton, rfq

2631

H. Danared, M. Eshraqi, W. Hees, A. Jansson, M. Lindroos, S. Peggs, A. Ponton
ESS, Lund, Sweden

The European Spallation Source will use a 2.5 GeV, 50 mA pulsed proton linac to produce an average 5 MW of power on the spallation target. It will consist of normal-conducting part accelerating particles to 50 MeV in an RFQ and a drift-tube linac and a superconducting part with spoke resonators and two families of elliptical cavities. A high-energy beam transport takes the particles through an upgrade section and at least one bend and demagnifies the beam on to the target. The paper will present the current layout of the linac and discuss parameters that define its length from source to target.

WEPS060

Design and Optimization of ESS LINAC

linac, quadrupole, proton, cryomodule

2634

M. Eshraqi
ESS, Lund, Sweden

The {\sc linac} of the European Spallation Source will accelerate the proton beam to its final energy mainly by using superconducting structures. Therefore choosing the right transition energy between these superconducting structures as well as choosing the cavity length and number of cells which enhances the acceleration is of great importance. Two types of {\sc linac}s will be studied, a {\sc linac} with superconducting quadrupoles and a {\sc linac} with normal conducting, resistive, quadrupoles. The procedure to find the optimized {\sc linac} will be described here.

WEPS061

ESS LINAC, Design and Beam Dynamics

linac, emittance, quadrupole, proton

2637

M. Eshraqi, H. Danared
ESS, Lund, Sweden

The European Spallation Source, {\sc ESS}, will use a linear accelerator delivering a high intensity proton beam with an average beam power of 5~MW to the target station at 2.5~GeV in long pulses of 2~msec. The ESS {\sc Linac} will use two types of superconducting cavities, spoke resonators at low energy and elliptical cavities at high energies. The possibilities to upgrade to a higher power {\sc Linac} at fixed energy are considered. This paper will present a review of the superconducting {\sc Linac} design and the beam dynamics studies.

WEPS062

Design and Beam Dynamics Study of Hybrid ESS LINAC

linac, cryomodule, accelerating-gradient, proton

2640

M. Eshraqi, H. Danared, W. Hees, A. Jansson
ESS, Lund, Sweden

The European Spallation Source, {\sc ESS}, will use a superconducting linear accelerator delivering high current long pulses with an average beam power of 5~MW to the target station at 2.5~GeV. A new cryomodule architecture is proposed which allows for a transition between cryomodules in the sub-100~K region, this region can work even at room temperature. This new hybrid design will generate a lower heat load with respect to a fully segmented design - while still providing easy access to individual cryomodules for maintenance and repair. This paper will present a review of the {\sc linac} design, beam dynamics studies and a preliminary cryogenic analysis of the transition region.

WEPS063

Compersation of Effect of Malfunctioning Spoke Resonators on Ess Beam Quality

linac, quadrupole, DTL, proton

2643

M. Eshraqi
ESS, Lund, Sweden

The {\sc linac} of the European Spallation Source will accelerate the proton beam to 2.5~GeV, 98\% of this energy is gained using superconducting structures. The superconducting {\sc linac} is composed of two types of cavities, double spoke resonators and five-cell elliptical cavities. The {\sc linac}, which is five times more powerful than the most powerful existing {\sc linac}, and the spoke cavities that have never been used at such a scale make it necessary to study the effect of one or a few spoke resonators not functioning properly and to find a solution where the defect is compensated by retuning of the neighbouring cavities.

WEPS064

Upgrade Strategies for High Power Proton Linacs

linac, target, neutron, proton

2646

M. Lindroos, H. Danared, M. Eshraqi, D.P. McGinnis, S. Molloy, S. Peggs, K. Rathsman
ESS, Lund, Sweden
R.D. Duperrier
CEA/DSM/IRFU, France
J. Galambos
ORNL, Oak Ridge, Tennessee, USA

High power proton linacs are used as drivers for spallation neutron sources, and are proposed as drivers for sub-critical accelerator driven thorium reactors. A linac optimized for a specific average pulse current can be difficult, or inefficient, to operate at higher currents, for example due to mis-matching between the RF coupler and the beam loaded cavity, and due to Higher Order Mode effects. Hardware is in general designed to meet specific engineering values, such as pulse length and repetition rate, that can be costly and difficult to change, for example due to pre-existing space constraints. We review the different upgrade strategies that are available to proton driver designers, both for linacs under design, such as the European Spallation Source (ESS) in Lund, and also for existing linacs, such as the Spallation Neutron Source (SNS) in Oak Ridge. Potential ESS upgrades towards a beam power higher than 5 MW preserve the original time structure, while the SNS upgrade is directed towards the addition of a second target station.

WEPS065

Segmentation in the Project-X Low Energy CW Linac Front End

focusing, linac, solenoid, lattice

2649

J.-F. Ostiguy, B.G. Shteynas, N. Solyak
Fermilab, Batavia, USA

Funding: Fermi National Accelerator Laboratory (Fermilab) is operated by Fermi Research Alliance, LLC. for the U.S. Department of Energy under contract DE-AC02-07CH11359
The low-energy front-end of the Project-X 2.5 MeV - 3 GeV linac utilizes superconducting single-spoke resonators for acceleration and solenoids for transverse focusing. To take advantage of the available accelerating field in the cavities, it is necessary to minimize the period length. This leads to a compact arrangement of cavities and solenoids with very minimal open longitudinal space. While beam position monitors and correctors can be integrated to the solenoid assemblies inside a cryostat, some instrumentation such as beam profile monitors require dedicated warm longitudinal space. In this paper we discuss an arrangement where the front-end is segmented in crystats comprising about half a dozen lattice periods separated by a minimal amount of warm longitudinal space. We discuss the impact of introducting such openings and present an optical solution integrating them. The strategy and constraints leading to this solution are outlined.

WEPS066

Residual Focusing Asymmetry in Superconducting Spoke Cavities

focusing, linac, solenoid, lattice

2652

J.-F. Ostiguy, N. Solyak
Fermilab, Batavia, USA

Funding: Fermi National Accelerator Laboratory (Fermilab) is operated by Fermi Research Alliance, LLC. for the U.S. Department of Energy under contract DE-AC02-07CH11359.
Project-X is a proposed high intensity proton source at Fermilab. Protons (H⁻) are first accelerated from 2.5 to 3 GeV in a superconducting linac operating in CW mode. While most of the particles are delivered to a variety of precision experiments, a fraction ( about 10%) is further accelerated to 8 GeV in a second superconducting linac operating in pulsed mode. In the low energy front-end of the first stage CW linac, single-spoke cavities are used for acceleration while solenoids and quadrupole doublets provide transverse focusing. The transverse rf defocusing arising from the spoke cavities has a small residual asymmetry whose effect can become noticeable in periods where the transverse phase advance is low. In this paper we discuss this effect, its practical consequences, as well as possible mitigation strategies.

WEPS067

An H-Mode Accelerator with PMQ Focusing as a LANSCE DTL Replacement

DTL, linac, focusing, proton

2655

S.S. Kurennoy, L. Rybarcyk, T.P. Wangler
LANL, Los Alamos, New Mexico, USA

High-efficiency normal-conducting RF accelerating structures based on H-mode cavities with a transverse beam focusing by permanent-magnet quadrupoles (PMQ) have been developed for beam velocities in the range of a few percent of the speed of light*. At these low beam velocities, an inter-digital H-mode (IH-PMQ) linac is an order of magnitude more efficient than a standard drift-tube linac (DTL). At the Los Alamos Neutron Science Center (LANSCE), upgrades of the proton linac front end are currently under consideration. In view of these plans, we explore a further option of replacing the aging LANSCE DTL by an efficient H-PMQ accelerator. Here we assume that a 201.25-MHz RFQ-based front end up to 750 keV (4% of the speed of light) is followed first by IH-PMQ structures and then by cross-bar H-mode cavities with PMQ focusing (CH-PMQ). Such an H-PMQ linac would bring proton and H⁻ beams to the energy of 100 MeV and transfer them into the existing side-coupled-cavity linac (CCL). Results of the combined electromagnetic and beam-dynamics modeling of the proposed H-PMQ accelerator will be presented.
* S.S. Kurennoy et al., “H-Mode Accelerating Structures with PMQ Beam Focusing,” PRST-AB, 2011 (submitted).

WEPS072

A Superconducting Ring Cyclotron to Search for CP Violation in the Neutrino Sector

cyclotron, extraction, injection, focusing

2670

L.A.C. Piazza, M.M. Maggiore
INFN/LNL, Legnaro (PD), Italy
L. Calabretta, D. Campo, D. Rifuggiato
INFN/LNS, Catania, Italy
A. Calanna
CSFNSM, Catania, Italy

Multi Megawatt accelerators are today requested for different use. In particular the experiment DAEdALUS*, recently proposed by MIT scientist to search for CP violation in the neutrino sector, needs three accelerator with energy of about 800 MeV, average power of some MW and duty cycle of 20%. To reduce the cost of the accelerators a cyclotron complex consisting of an injector** and of a booster ring cyclotron has been proposed***. The booster Superconducting Ring Cyclotron, able to accelerate a H²⁺ molecule beam up to 800 MeV/n and average power higher than 1.6 MW, will be described. Although the average power is 1.6 MW, due to the low duty cycle, the peak power will be 8 MW. The main advantages to accelerate H²⁺ are a reduction of space charge effects, a simple extraction process, extraction of two beams at the same time from each booster cyclotron to simplify the beam dump. The features of the magnetic sector, of the superconducting coils and the magnetic forces evaluated by the code TOSCA are presented. The isochronous magnetic field, the beam dynamics along the injection and extraction path and during the acceleration are presented, too.
*J.Alonso etal., Novel Search for CP Violation in the Neutrino Sector: DAEdALUS, June2010;e-Print arXiv:10⁰⁶.0260.
**L.Calabretta, IPAC 2011,this conference.
***L.Calabretta, Cyclotrons 2010, Lanzhou.

WEPS073

A Low Energy Cyclotron Injector for DAEdALUS Experiment

cyclotron, proton, extraction, space-charge

2673

L.A.C. Piazza, M.M. Maggiore
INFN/LNL, Legnaro (PD), Italy
L. Calabretta, D. Campo, D. Rifuggiato
INFN/LNS, Catania, Italy
A. Calanna
CSFNSM, Catania, Italy

Multi Megawatt accelerators are today requested for different use. In particular the experiment DAEdALUS*, recently proposed by MIT scientist to search for CP violation in the neutrino sector, needs three accelerator with energy of about 800 MeV, average power of some MW and duty cycle of 20%. To reduce the cost of the accelerators a cyclotron complex consisting of an injector and of a booster ring cyclotron has been proposed**. The main characteristics of the new kind of a separated sector cyclotron injector able to accelerate a H²⁺ molecule beam up to 50 MeV/n will be presented. Due to the low duty cycle, the peak current to be accelerated is 5 mA. The problem related to the injection of a H²⁺ beam, delivered by a compact ion source, and to the space charge effects will be discussed. The main parameters of the magnetic sectors, RF cavities, the isochronous magnetic field and the beam dynamics along the injection and extraction path and during the acceleration will be presented, too.
* J. Alonso et al., “A Novel Search for CP Violation in the Neutrino Sector: DAEdALUS”, June 2010. e-Print: arXiv:10⁰⁶.0260
** L. Calabretta et al., ICCA, Lanzhou 2010; http://www. JACoW.org.

WEPS080

Development of High-quality Intense Proton Beam at the RCNP Cyclotron Facility

proton, cyclotron, extraction, emittance

2694

M. Fukuda, K. Hatanaka, M. Kibayashi, S. Morinobu, K. Nagayama, T. Saito, H. Tamura, H. Ueda, H. Yamamoto, T. Yorita
RCNP, Osaka, Japan

A 2.45 GHz ECR proton source, equipped with a set of three permanent magnets, was developed to increase the intensity of a high-quality proton beam. A 15 keV proton beam with intensity of 0.6 mA was produced with a proton ratio of more than 80 %. Emittance of the proton beam with intensity of 50 to 100 micro-A in the LEBT system was around 50 pi-mm-mrad. Beam transmission, defined by the ratio of the beam intensity between a Faraday cup placed in the axial injection beam line and an inflector electrode of the AVF cyclotron, was improved from 25 % for a 70 micro-A proton beam to more than 90 % for 30 micro-A obtained by defining the injection beam with a beam slit of iris type. The result indicated that the beam transmission was limited by the acceptance of the axial injection beam line. Emittance of the 65 MeV proton beam accelerated by the K140 AVF cyclotron was a few pi-mm-mrad for beam intensity of several-micro-A. In this paper, development of the intense proton beam and evaluation of the proton beam quality will be mainly reported.

WEPS090

The Myrrha Linear Accelerator

linac, rfq, cryomodule, proton

2718

D. Vandeplassche
SCK-CEN, Mol, Belgium
J.-L. Biarrotte
IPN, Orsay, France
H. Klein, H. Podlech
IAP, Frankfurt am Main, Germany

Funding: European Atomic Energy Community's (EURATOM) Seventh Framework Programme FP7/2007-2011, grant agreement no. 269565 (MAX project)
Accelerator Driven Systems (ADS) are promising tools for the efficient transmutation of nuclear waste products in dedicated industrial installations, called transmuters. The Myrrha project at Mol, Belgium, placed itself on the path towards these applications with a multipurpose and versatile system based on a liquid PbBi (LBE) cooled fast reactor (80 MWth) which may be operated in both critical and subcritical modes. In the latter case the core is fed by spallation neutrons obtained from a 600 MeV proton beam hitting the LBE coolant/target. The accelerator providing this beam is a high intensity CW superconducting linac which is laid out for the highest achievable reliability. The combination of a parallel redundant and of a fault tolerant scheme should allow obtaining an MTBF value in excess of 250 hours that is required for optimal integrity and successful operation of the ADS. Myrrha is expected to be operational in 2023. The forthcoming 4-year period is fully dedicated to R&D activities, and in the field of the accelerator they are strongly focused on the reliability aspects and on the proper shaping of the beam trip spectrum.

WEPS097

Performance of Multi-harmonic RF Feedforward System for Beam Loading Compensation in the J-PARC RCS

impedance, beam-loading, acceleration, beam-losses

2733

F. Tamura, M. Nomura, A. Schnase, T. Shimada, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
K. Hara, C. Ohmori, M. Toda, M. Yoshii
KEK/JAEA, Ibaraki-Ken, Japan
K. Hasegawa
KEK, Tokai, Ibaraki, Japan

The beam loading compensation is a key part for acceleration of high intensity proton beams in the J-PARC RCS. In the wide-band MA-loaded RF cavity, the wake voltage consists of not only the accelerating harmonic component but also the higher harmonics. The higher harmonic components cause the RF bucket distortion. We employ the RF feedforward method to compensate the multi-harmonic beam loading. The full-digital feedforward system is developed, which compensates the first three harmonic components of the beam loading. We present the results of the beam test with a high intensity proton beam (2.5·10¹³ ppp). The impedance seen by the beam is greatly reduced, the impedance of the fundamental accelerating harmonic is reduced to less than 25 ohms in a full accelerating cycle, while the shunt resistance of the cavity is in the order of 800 ohms. The performance of the feedforward system is promising for achievement of the design beam power, 1 MW, in the future.

WEPS102

Latest News on the Beam Dynamics Design of SPL

linac, emittance, quadrupole, lattice

2748

P.A. Posocco, M. Eshraqi, A.M. Lombardi
CERN, Geneva, Switzerland

SPL is a superconducting H− LINAC under study at CERN. The SPL is designed to accelerate the 160 MeV beam of LINAC4 to 5 GeV, and is composed of two fami¬lies of 704.4 MHz elliptical cavities with geometrical betas of 0.65 and 1.0. Two families of cryo-modules are considered: the low-beta cryo-module houses 3 low-beta cavities, whereas the high-beta one houses 8 cavities. The transverse focusing is performed with normal-conducting quadrupoles arranged in 2 different lattices: FD0 at lower and F0D0 at higher energies. The regular lattices are in-terrupted at the transition between low beta and high beta cryo-modules and for extracting medium energy beams at 1.4 and 2.5 GeV, where the change of the transverse lattice is performed. In this paper the latest beam dynamics studies will be presented together with the sensitivity of the SPL performance to RF errors, alignment tolerances and quadrupole high order components.

WEPZ007

Multi-mode, Two-beam Accelerator with Feedback

feedback, impedance, accelerating-gradient, RF-structure

2778

S.V. Kuzikov, M.E. Plotkin
IAP/RAS, Nizhny Novgorod, Russia

A high-gradient accelerator consisted of the test and the drive beam structures is reported. The accelerating structure can be based on dielectric or corrugated cavities separated each other by irises. Each cavity is operated by several axisymmetric, TM-like eigen-modes with longitudinal indices to be related to frequencies. These modes are excited at Fourier harmonics of the drive current which consists of bunches spaced with the same period as test bunches. The superposition of the excited modes introduces a short RF pulse propagated in-phase with a moving test bunch and after reflection by iris (a feedback) this pulse can accelerate next bunch. Such longitudinally-sweeping RF field promises a reduction of the exposure time and due to compact space shape can help to obtain high shunt impedance.

WEPZ015

Staging in Two Beam Dielectric Wakefield Accelerators

acceleration, wakefield, kicker, septum

2802

J.G. Power, M.E. Conde, W. Gai, C.-J. Jing
ANL, Argonne, USA

Funding: The work is supported by the U.S. Department of Energy under Contract No. DE-AC02-06CH11357 with Argonne National Laboratory.
A new experimental program to demonstrate staging in a two beam dielectric wakefield accelerator (DWA) is being planned at the Argonne Wakefield Accelerator facility. DWA uses a drive beam to generate acceleration fields to accelerate a main beam and is one of the most promising advanced acceleration methods being pursued for a future high-energy physics linear collider. Staging is the ability to use two accelerating modules back to back to accelerate a charged particle bunch and it is one of basic requirements of any acceleration method. In this paper, a new beamline design consisting of a fast kicker to pick pulses from the drive bunch train and deliver them to the individual acceleration modules will be presented.

THOBB02

High Gradient Magnetic Alloy Cavities for J-PARC Upgrade

impedance, synchrotron, proton, status

2885

C. Ohmori, O. Araoka, E. Ezura, K. Hara, K. Hasegawa, A. Koda, Y. Makida, Y. Miyake, R. Muto, K. Nishiyama, T. Ogitsu, H. Ohhata, K. Shimomura, A. Takagi, K. Takata, K.H. Tanaka, M. Toda, M. Yoshii
KEK, Tokai, Ibaraki, Japan
T. Minamikawa
University of Fukui, Fukui, Japan
M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan

Magnetic alloy cavities are used for both MR and RCS synchrotrons. Both cavity systems operate successfully and they generate a higher voltage than could be achieved by an ordinary ferrite cavity system. For the future upgrade of J-PARC, a higher RF voltage is needed. A new RF cavity system using the material, FT3L, is designed to achieve this higher field gradient. A large production system using an old cyclotron magnet was constructed to anneal 85-cm size FT3L cores in the J-PARC Hadron Experiment Hall. The muSR (Muon Spin Rotation/Relaxation/Resonance) Experiments were also carried out to study the magnetic alloy. The status of development on the J-PARC site and a new RF system design will be reported.

Slides THOBB02 [2.729 MB]

THPPA00

Study of Beam Diagnostics with Trapped Modes in Third Harmonic Superconducting Cavities at FLASH

dipole, HOM, simulation, electron

2891

P. Zhang
DESY, Hamburg, Germany
P. Zhang
UMAN, Manchester, United Kingdom

Contribution selected for EPS-AG Prize d). Off-axis beams passing through an accelerating cavity excite dipole modes among other higher order modes (HOMs). These modes have linear dependence on the transverse beam offset from the cavity axis. Therefore they can be used to monitor the beam position within the cavity. The fifth dipole passband of the third harmonic superconducting cavities at FLASH has modes trapped within each cavity and do not propagate through the adjacent beam pipes, while most other cavity modes do. This could enable the beam position measurement in individual cavities. This paper investigates the possibility to use the fifth dipole band for beam alignment in the third harmonic cavity module. Simulations and measurements both with and without beam-excitations are presented. Various analysis methods are used and compared. A good correlation of HOM signals to the beam position is observed.

Slides THPPA00 [2.740 MB]

THPC003

Installation of the ASTRID2 Synchrotron Light Source

extraction, kicker, dipole, vacuum

2909

J.S. Nielsen, N. Hertel, S.P. Møller
ISA, Aarhus, Denmark

ASTRID2 is the new 10 nm UV and soft x-ray light source being built at Aarhus University, to replace the aging source ASTRID. ASTRID2 is now in the middle of its installation. An update of the design will be presented. Almost all components have now been acquired and received. Several choices and solutions of hardware will be described, and future commissioning plans outlined. Commissioning is expected to take place in the winter 2011/2012.

THPC009

Performance and Upgrade of the ESRF Light Source

emittance, undulator, storage-ring, vacuum

2924

J.-L. Revol, J.C. Biasci, J-F. B. Bouteille, J. Chavanne, F. Ewald, L. Farvacque, A. Franchi, G. Gautier, L. Goirand, M. Hahn, L. Hardy, J. Jacob, J.M. Koch, M.L. Langlois, G. Lebec, J.M. Mercier, T.P. Perron, E. Plouviez, K.B. Scheidt, V. Serrière
ESRF, Grenoble, France

The European Synchrotron Radiation Facility (ESRF) is now fully engaged in a large Upgrade Programme of its infrastructure, beamlines and X ray source. In this context, a first set of 10 insertion device straight sections are being lengthened from five to six metres; a number of them will be operated with canted undulators. The insertion devices are themselves subject to an ambitious development programme to fulfil the scientific requirements. The Radio Frequency system upgrade has started with the replacement of the booster klystron-based transmitter by high power solid state amplifiers, and the development of HOM damped cavities operating at room temperature. A completely new DC-AC orbit stabilization system using 224 BPMs and 96 orbit steerers is currently being commissioned. The upgrade is conducted while keeping, and even improving, routine performance for the user service. In particular the recent installation of new skew quadrupole power supplies allows routine operation with ultra low vertical emittance. This paper reports on the present operation performance of the source, highlighting recent developments and those still to come.

THPC014

Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring

optics, focusing, radiation, electron

2936

G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries
HZB, Berlin, Germany

A scheme is discussed, where short and long bunches can be stored simultaneously in the BESSY II storage ring. With recent developments in sc-rf cavity technology it becomes possible, to install high gradient cavities in electron storage rings. With an appropriate choice of these cavities stable fixed points with different rf-voltage gradients are available, leading to different zero current bunch lengths. For BESSY II, we discuss the simultaneously storage of bunches with rms-lengths of 2 ps and 15 ps at high beam intensities. Additionally, in a low alpha optics sub-ps and ps-bunches are possible and a double bucket optics can be set up to store the two types of beams simultaneously on different orbits. Ultra-short and long bunches can be supplied to the users, separated by slightly different orbits.

THPC021

Status of Bunch Deformation and Lengthening Studies at the ANKA Storage Ring

radiation, diagnostics, storage-ring, photon

2951

N. Hiller, A. Hofmann, E. Huttel, V. Judin, B. Kehrer, M. Klein, S. Marsching, A.-S. Müller
KIT, Karlsruhe, Germany

Funding: This work has been supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320.
At the ANKA storage ring (Karlsruhe, Germany) we use a Hamamatsu synchroscan streak camera to study the current dependent bunch lengthening and deformation effects . Previously the camera was used at an IR port, being available only occasionally. In October 2010, a dedicated “beam line” for the streak camera became operational. It is designed to have minimum dispersion and sufficient flux in the optical range at which the camera is most sensitive. This allows us to measure bunch profiles for a single bunch with a charge of less than 15 pC (40 μA), previously more than 55 pC were required to obtain a comparable signal. Along with the design and built-up, we present further measurements of bunch length and shape for different momentum compaction factors, RF voltages, beam energies and bunch charges to provide a complete bunch length map of the low alpha mode at ANKA.

THPC041

Injector System of Test Accelerator as Coherent Terahertz Source

gun, electron, cathode, radiation

2993

S. Kashiwagi, H. Hama, F. Hinode, M. Kawai, X. Li, T. Muto, K. Nanbu, Y. Tanaka
Tohoku University, School of Science, Sendai, Japan
N.Y. Huang
NTHU, Hsinchu, Taiwan
F. Miyahara
KEK, Ibaraki, Japan

Funding: This work is supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (S), Contract #20226003.
A test accelerator as a coherent terahertz source (t-ACTS) project has been under development at Tohoku University, in which a generation of intense coherent terahertz (THz) radiation from sub-picosecond electron bunch will be demonstrated. We will supply a wide-band coherent radiation from bending magnets in an isochronous ring and a narrow-band coherent THz radiation using an undulator in a linac. Stable generation of very short electron bunch is one of the key issues in the t-ACTS project. The injector system is consists of a thermionic RF gun with two independent cavity cells, an alpha magnet and an accelerating structure. A velocity bunching scheme is employed to produce the very short electron bunch. Components of the t-ACTS injector except the accelerating structure have already been installed and we have started a high power RF processing of the gun cavities. The characteristics of electron bunch extracted from the RF gun are measured by varying phase and amplitude of input RF fields for the gun cavities. The status of t-ACTS project will be presented in the conference.

THPC045

Design of a Compact Storage Ring for the TTX

injection, kicker, scattering, emittance

3005

H.S. Xu, W.-H. Huang, C.-X. Tang
TUB, Beijing, People's Republic of China
S.-Y. Lee
IUCEEM, Bloomington, Indiana, USA

We study a compact storage ring with circumference 3-m, 4 dipoles, and two quadrupoles for the Tsinghua Thomson scattering X-ray (TTX) source. The effects of Touschek lifetime, rf system requirement, the Intra-beam scattering (IBS) and coherent synchrotron radiation (CSR) will be addressed. A top-up injection system will be designed to maximize the Photon flux. Conceptual laser cavity to enhance photon flux will be discussed. Expected performance of the compact X-ray source will be presented.

THPC054

Project Status of the Polish Synchrotron Radiation Facility Solaris

storage-ring, linac, synchrotron, radiation

3014

C.J. Bocchetta, P.P. Goryl, K. Królas, M. Mlynarczyk, M.J. Stankiewicz, P.S. Tracz, Ł. Walczak, A.I. Wawrzyniak
Solaris, Krakow, Poland
J. Ahlbäck, Å. Andersson, M. Eriksson, M.A.G. Johansson, D. Kumbaro, S.C. Leemann, L. Malmgren, J.H. Modéer, P.F. Tavares, S. Thorin
MAX-lab, Lund, Sweden
E. Al-dmour, D. Einfeld
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

Funding: European Regional Development Fund within the frame of the Innovative Economy Operational Program: POIG.02.01.00-12-213/09
The Polish synchrotron radiation facility Solaris is being built at the Jagiellonian University in Krakow. The project is based on an identical copy of the 1.5 GeV storage ring being concurrently built for the MAX IV project in Lund, Sweden. A general description of the facility is given together with a status of activities. Unique features associated with Solaris are outlined, such as infra-structure, the injector and operational characteristics.

THPC070

An Automated Statistical Analysis Package for the Study of Synchrotron Light Source Operation

storage-ring, beam-losses, monitoring, synchrotron

3056

C. Christou, C.P. Bailey, V.C. Kempson, V.J. Winter
Diamond, Oxfordshire, United Kingdom

Machine faults and interruptions to user beam at Diamond Light Source are recorded in a Fault Log Database (FLDB) running under Microsoft Access. The scope of numerical analysis in Access is limited, and so an advanced data analysis package has been written in Matlab to exploit the powerful numeric functions available in this environment to automatically analyze machine faults and summarize data for reliability reports. Figures of merit such as mean time between failure (MTBF), mean time to repair (MTTR), total up time and total number of faults over the machine as a whole and by technical group can be calculated, and more advanced Pareto and Weibull analyses can be instantly generated. Data is presented for Diamond Light Source both for the latest year of operation and since user beam began in 2007, and the impact of different technical groups, in particular the storage ring RF, is considered. Failure distributions and the underlying hazard functions are produced and compared with statistical models to highlight deviations from randomly occurring events and to quantify changes in failure probability with time.

THPC080

Making Engineering Data Available at the European XFEL

cryogenics, survey, LLRF, photon

3077

L. Hagge, J. Bürger, J.A. Dammann, S. Eucker, A. Herz, J. Kreutzkamp, S. Panto, S. Sühl, D. Szepielak, N. Welle
DESY, Hamburg, Germany

One of the essential success factors for the European XFEL is up-to-date, complete and consistent engineering data which is readily accessible throughout the project. Such data include for example civil construction drawings of tunnels and buildings; integrated 3D models of accelerator sections; definitions of fabrication processes and test procedures; inspection sheets, test data, standards, contracts and other technical documentation. The data is kept in the DESY Engineering Data Management System (EDMS). The DESY EDMS is the central information platform for the European XFEL and provides procedures for e.g. review & approvals and change management. The poster presents an overview of Engineering Data Management and its benefits at the European XFEL.

THPC085

Effect of mirror-tilt on the mode-structure in an oscillator FEL

FEL, coupling, simulation, alignment

3092

S. Krishnagopal, S.A. Samant
BARC, Mumbai, India

In an oscillator free-electron laser (FEL) the power coupled out depends strongly on the mode configuration at the out-coupling mirror. This mode configuration is affected by many parameters such as the resonator configuration, FEL wavelength, etc. In addition, mirror alignment also plays an important role in determining the mode structure. In this paper we use three-dimensional simulations (GENESIS+OPC), to study the effect of mirror tilt on the out-coupled power. We find that mirror-tilt can severely distort the mode, and can introduce non-Gaussian, non-axisymmetric modes. In this regard the confocal configuration is more robust compared to the concentric.

THPC088

Performance of RF System for XFEL/SPring-8 Injector

gun, emittance, electron, klystron

3101

T. Asaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
T. Asaka, H. Ego, H. Hanaki, T. Kobayashi, S. Suzuki, T. Taniuchi
JASRI/SPring-8, Hyogo-ken, Japan
T. Inagaki
RIKEN/SPring-8, Hyogo, Japan
Y. Otake, T. Shintake, K. Togawa
RIKEN Spring-8 Harima, Hyogo, Japan

In the XFEL/SPring-8 accelerator, the RF processing of an injector for the 8-GeV accelerator were carried out during two months after the installation of all the main components of the accelerator was completed in January 2011. To realize stable bunch compression process without the emittance growth, the injector adopts the combination of an extremely low emittance thermionic gun and multi-stage RF cavities for velocity bunching. In addition, in order to reduce the emittance growth occurring at the transition from the velocity bunching to acceleration, the newly developed L-band APS type accelerating structures and a waveguide system were introduced in the injector. Since an intensity of beam current is affected by the slight variations of RF power and phase of these RF equipment, we have carried out thorough countermeasures to complete highly-stabilized RF systems. Consequently, the stability of RF power and phase in rated operating condition of each RF cavity achieved 20 ppm (std.) and 0.06˚ (std.), respectively. In this paper, we describe the stability performances and RF processing of these RF systems in the injector.

THPC109

First Demonstration of Electron Beam Generation and Characterization with an All Superconducting Radio-frequency (SRF) Photoinjector*

SRF, laser, cathode, solenoid

3143

T. Kamps, W. Anders, R. Barday, A. Jankowiak, J. Knobloch, O. Kugeler, A.N. Matveenko, A. Neumann, T. Quast, J. Rudolph, S.G. Schubert, J. Völker
HZB, Berlin, Germany
P. Kneisel
JLAB, Newport News, Virginia, USA
R. Nietubyc
The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock, Poland
J.K. Sekutowicz
DESY, Hamburg, Germany
J. Smedley
BNL, Upton, Long Island, New York, USA
V. Volkov
BINP SB RAS, Novosibirsk, Russia
G. Weinberg
FHI, Berlin, Germany
I. Will
MBI, Berlin, Germany

Funding: Work supported by Bundesministerium für Bildung und Forschung und Land Berlin. The work on the Pb cathode film is supported by EuCARD Grant Agreement No. 227579
In preparation for a high brightness, high average current electron source for the energy-recovery linac BERLinPro an all superconducting radio-frequency photoinjector is now in operation at Helmholtz-Zentrum Berlin. The aim of this experiment is beam demonstration with a high brightness electron source able to generate sub-ps pulse length electron bunches from a superconducting (SC) cathode film made of Pb coated on the backwall of a Nb SRF cavity. This paper describes the setup of the experiment and first results from beam measurements.

THPC111

Operation of an L-band RF Gun with Pulses Inside the Burst Mode RF Pulse

gun, laser, klystron, controls

3146

V. Vogel, V. Ayvazyan, B. Faatz, K. Flöttmann, D. Lipka, P. Morozov, H. Schlarb, S. Schreiber
DESY, Hamburg, Germany

The Free-Electron Laser in Hamburg (FLASH) is a user facility since 2005, delivering femtosecond short radiation pulses in the wavelength range between 4.1 and 44 nm using the SASE principle. In FLASH, the electron beam is accelerated to 1.25 GeV with L-band superconducting cavities. The electron source is a normal conducting RF-gun photoinjector. The L-band standing wave RF gun has one and a half cells. The gun is operated in burst mode with an RF pulse length of up to 900 microseconds and a repetition rate of 10 Hz. Several hundreds to thousands of bunches are accelerated per second. With 5 MW of pulsed forward power, the dissipated power inside the RF gun is 45 kW. In this paper we propose an operational mode which allows us to reduce the dissipated power to ease operation or to increase the effective duty cycle in the gun by pulsing the gun within one burst. We report on first experimental results at FLASH, where an RF burst of 46μRF-pulses with a length of 10 microseconds separated by 10 microseconds has been successfully generated reducing the dissipated power by a factor of 2.

THPC118

Present Status of Quantum Radiation Sources on the Basis of the S-band Compact Electron Linac

laser, electron, radiation, linac

3164

R. Kuroda, E. Miura, H. Toyokawa, K. Yamada, E. Yamaguchi
AIST, Tsukuba, Ibaraki, Japan
M. Kumaki
RISE, Tokyo, Japan

We have developed quantum radiation sources such as a laser Compton scattering (LCS) X-ray and a coherent THz radiation sources on the basis of the S-band compact electron linac at AIST in Japan. The S-band linac consists of the laser-driven photocathode rf gun and two 1.5 m-long acceleration tubes and can accelerate the electron beam up to about 42 MeV. The LCS X-ray source can generate a quasi-monochromatic hard X-ray with variable energy of 12 - 40 keV for medical and biological applications. Now, the multi-collision LCS system has been developed with the regenerative amplifier type laser storage cavity and the multi-bunch electron beam to increase the X-ray yield. On the other hand, the high-power coherent THz radiation source has been also developed and its peak power is estimated to be more than 1 kW in frequency range between 0.1 - 2 THz. The high-power THz radiation was applied to the scanning transmission imaging. Now, the high power THz time domain spectroscopy (TDS) has been developed for the material science. In this conference, we will report the present status of the S-band compact electron linac, our quantum radiation sources and applications.

THPC132

A Velocity Bunching Scheme for Creating Sub-picosecond Electron Bunches from an RF Photocathode Gun

gun, emittance, solenoid, laser

3194

J.W. McKenzie, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Sub-picosecond electron bunches are in demand for various applications including Free Electron Lasers and electron diffraction experiments. Typically, for Free Electron Lasers, a multiple picosecond scale bunch is produced from a photoinjector with compression achieved via one or more magnetic chicanes by providing an appropriate energy chirp to the bunch in the preceding linac sections. This approach is complex, requiring many components, often including a higher harmonic linac section to linearise the longitudinal phase-space, and careful tuning in order to minimise emittance blow-up due to coherent synchrotron radiation. We present a scheme to deliver sub-picosecond electron bunches, based on a normal conducting RF gun and two short linac sections, one for providing velocity bunching and the second to capture the compressed bunch and accelerate to tens of MeV where the beam properties are then essentially frozen.

THPC169

Short-Period RF Undulator for a Nanometer SASE Source

undulator, electron, injection, radiation

3293

S.V. Kuzikov, M.E. Plotkin, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia
J.L. Hirshfield
Yale University, Physics Department, New Haven, CT, USA
T.C. Marshall, G.V. Sotnikov
Omega-P, Inc., New Haven, Connecticut, USA

Funding: Sponsored in part by US Department of Energy, Office of High Energy Physics.
A room-temperature RF undulator to produce ~1 nm wavelength radiation using a relatively low energy electron beam (0.5 GeV) is considered. The design features include an effective undulator period of 0.45 cm, an undulator parameter of K = 0.4, an effective field length of 50 cm. These parameters could be be realized using a multi-MW RF power amplifier to drive the undulator (e.g., the 34 GHz pulsed magnicon at Yale or a 30 GHz gyroklystron at IAP) with microsecond pulse duration. Two undulator designs were considered that avoid problems with a co-propagating wave: a dual-mode cylindrical cavity [TE01 (counter propagating) - TE02 (co-propagating)] with an off-axis electron beam; and a traveling HE11 mode resonant ring with an on-axis beam.

THPC179

Electron Beam Heating and Operation of the Cryogenic Undulator and Superconducting Wigglers at Diamond

electron, wiggler, undulator, synchrotron

3323

J.C. Schouten, E.C.M. Rial
Diamond, Oxfordshire, United Kingdom

Diamond Light Source has two superconducting wigglers and one cryocooled undulator installed serving three beam lines. The cryocooled undulator (cpmu) has been operating since August 2010 while the superconducting wigglers have been operating for more than 4 years (SCW-1) and 2 years (SCW-2). We will report on the first year of operation of the cpmu including details of its spectral output and cryogenic performance. Our experience of the cooling system and measures taken to ensure reliability and to minimize the risks of a prolonged downtime are also presented. The two superconducting wigglers are exposed to a high heat load due to the beam heating of the inner liner. Until recently this resulted in a much higher helium consumption than specified and so recently a new liner has been fitted to SCW-1 and new re-condensers to SCW-2. In addition a thermal bridge has been made between the RF tapers and the outer heat shield of both SCW-1 and SCW-2. The results of these improvements will be presented.

THPC183

Application of the Balanced Hybrid Mode in Overmoded Corrugated Waveguides to Short Wavelength Dynamic Undulators

undulator, impedance, FEL, electron

3326

S.G. Tantawi, G.B. Bowden, C. Chang, J. Neilson, M. Shumail
SLAC, Menlo Park, California, USA
C. Pellegrini
UCLA, Los Angeles, California, USA

Funding: Work Supported by the US Department of Energy
Inspired by recent developments in low-loss overmoded components and systems for ultra-high power RF systems, we explored several overmoded waveguide systems that could function as RF undulators. One promising structure is a corrugated waveguide system operating at the hybrid HE11 mode. This is a new application for that mode. Initial calculations indicate that such a system can be operated at relatively low power levels while obtaining large values for the undulator parameters. RF surface fields are typically low enough to permit superconducting operation. This technology could realize an undulator with short wavelengths and also dynamic control of the undulator parameters including polarization. We introduce the scaling laws governing such a structures, and then show with exact simulations an undulator design that have a wavelength of about 1.4 cm with an undulator parameter K~1. This undulator is intended to be powered by a 50 MW source at a frequency of 11.4 GHz. We describe the experimental setup for testing such a technology.

THPS008

Bucked Coils Lattice for the Neutrino Factory

lattice, emittance, factory, betatron

3439

A. Alekou, J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
C.T. Rogers
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

In the Neutrino Factory muon front end, ionization cooling is used to reduce the very large initial transverse muon beam emittance. The current baseline cooling channel, FSIIA, performs well in simulations with respect to the transmission and cooling. However, recent studies indicate the RF voltage may be limited when external magnetic field is applied and therefore, as the FSIIA lattice has a large magnetic field at the position of the RF cavities, the feasibility of FSIIA may be questioned. Bucked Coils lattice, a new cooling lattice that uses different radius and opposite polarity coils placed at the same position along the beam-axis, aims to achieve low magnetic field at the position of the RF cavities while obtaining comparable transmission to FSIIA. The detailed comparison between FSIIA and different versions of the Bucked Coils configuration with respect to the magnetic field, beam dynamics and transmission are presented in this paper.

THPS016

Rare Ion Beam (RIB) Facility at VECC : Present and Future

ion, rfq, ion-source, acceleration

3454

R.K. Bhandari, A. Bandyopadhyay, A. Chakrabarti, V. Naik
DAE/VECC, Calcutta, India

Funding: This project if funded by Department of Atomic Energy, Government of India.
An ISOL post accelerator type Rare Ion Beam (RIB) Facility is being developed at our centre. The RIBs will be produced by using light ion induced fusion evaporation and by using photo-fission reaction, using a 50 MeV 2mA SC electron linac that is being developed in collaboration with TRIUMF, Canada. The primary reaction products will be ionized using two-ion source charge breeder. The possibility of feeding the primary reaction products directly to an ECR ion source using multi-stage skimmer and gas jet transport technique is being explored at present. An extended rod type heavy ion RFQ, one buncher and three IH cavities have been successfully accelerated stable beams up to about 415 keV/u. Three more IH cavities will increase the energy to about 1.3 MeV/u and SC QWRs will augment the energy thereafter. In the next stage of development, an Advanced National Facility for Unstable & Rare Isotope Beams (ANURIB) has been envisaged. This green field project will deliver stable & RIBs from 1.5 keV/u to 100 MeV/u. This will have both ISOL type and PFS type facility. Neutron & positron beams based facilities will also be built around the e^- linac.

THPS038

Possibility of longitudinal painting injection with debuncher system in J-PARC linac

injection, linac, simulation, controls

3505

G.H. Wei
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

J-PARC linac is presently operating with the output energy of 181 MeV and providing a negative hydrogen beam to the succeeding 3-GeV synchrotron. To achieve the design beam power of 1 MW from the synchrotron, we plan to upgrade the linac beam energy to 400 MeV. In the energy upgrade, we replace the debuncher system installed between the linac and synchrotron. The main roles of the debuncher system are to correct the momentum jitter and to control the momentum spread at the ring injection. Usually, we don’t assume acceleration or deceleration with the debuncher cavities except for passive momentum jitter correction. However, we are studying the possibility of actively controlling the center momentum with debuncher cavities to enable longitudinal painting injection into the succeeding ring as a potential new feature. If it finds feasible, it would provide an additional tuning knob to mitigate the beam loss in the synchrotron. In this paper, we show a beam dynamics design of the new debuncher system with emphasis on the possibility of its application for the longitudinal painting injection.

THPS062

Cavity-recirculated Laser Charge Stripping of Hydrogen Ions

neutron, radiation, laser, ion

3568

I. Jovanovic
Penn State University, University Park, Pennsylvania, USA
R. Tikhoplav
RadiaBeam, Santa Monica, USA

Funding: This work is supported by the U.S. Department of Energy.
High-intensity proton accelerators such as those at the Oak Ridge National Laboratory’s Spallation Neutron Source require an intense, robust, reliable, and low-cost source of hydrogen ions. Laser-based charge stripping is a promising, high-efficiency method that could meet the requirements of present and future facilities. We are seeking to improve the efficiency of hydrogen ion stripping by an order of magnitude using laser recirculation. In our approach we recirculate a high-power laser using the technique termed recirculation injection by nonlinear gating, with a frequency-doubling nonlinear crystal as an efficient switch that allow pulse injection into the cavity. We present our progress on cavity development and the preliminary experimental assessment of cavity performance in high-radiation environment. Our experimental studies were conducted by irradiating the nonlinear crystal used in the laser cavity by fast neutrons in a research nuclear reactor and measuring its change in transmissivity.

THPS095

Q-factor of an Open Resonator for a Compact Soft X-ray Source based on Thomson Scattering of Stimulated Coherent Diffraction Radiation

radiation, electron, vacuum, scattering

3657

A.S. Aryshev, S. Araki, M.K. Fukuda, J. Urakawa
KEK, Ibaraki, Japan
V. Karataev
JAI, Egham, Surrey, United Kingdom
G.A. Naumenko
Tomsk Polytechnic University, Nuclear Physics Institute, Tomsk, Russia
A. Potylitsyn, L.G. Sukhikh, D. Verigin
TPU, Tomsk, Russia
K. Sakaue
RISE, Tokyo, Japan

High-brightness and reliable sources in the VUV and the soft X-ray region may be used for numerous applications in such areas as medicine, biology, biochemistry, material science, etc. We have proposed a new approach to produce the intense beams of X-rays in the range of eV based on Thomson scattering of Coherent Diffraction Radiation (CDR) on a 43 MeV electron beam. CDR is generated when a charged particle moves in the vicinity of an obstacle. The radiation is coherent when its wavelength is comparable to or longer than the bunch length. The CDR waves are generated in an opened resonator formed by two mirrors. In this report the status of the experiment, the first CDR measurements at the multibunch beam of the LUCX facility and general hardware design will be reported.

THPS102

Novel Schemes for the Narrow Band Sparc THz Source using a Comb like e-beam

linac, radiation, electron, laser

3672

B. Marchetti
INFN-Roma II, Roma, Italy
M. Boscolo, M. Castellano, E. Chiadroni, M. Ferrario, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy

The development of radiation sources in the THz spectral region has become more and more interesting because of the peculiar characteristics of this radiation: it is non ionizing, it penetrates dielectrics, it is highly absorbed by polar liquids, highly reflected by metals and reveals specific "fingerprint" absorption spectra arising from fundamentals physical processes. The THz source at SPARC is an accelerator based source for research investigations (e.g. material science, biology fields). By means of e-beam manipulation technique, a longitudinal modulated beam, the so-called comb beam, can be produced at Sparc. In terms of THz sources, such e-beam distribution allows to produce high intensitiy narrow band THz radiation, whose spectrum strongly depends on the charge distribution inside the e-beam. Different linac schemes are compared. In particular, spectra obtained using the comb-beam compression through velocity bunching including a IV harmonic RF section is showed.

THPZ013

A Proposal for the Optics and Layout of the HL-LHC with Crab-cavities

optics, insertion, luminosity, dynamic-aperture

3711

R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland

The LHC Upgrade studies have been recently formalized into the so-called HL-LHC project. This project relies on the availability of new technologies such as crab-cavities which would be installed in the interaction region (IR) of the new ATLAS and CMS experiments, and high-field and large aperture inner triplet quadrupoles equipped with Nb3Sn super-conducting cables. This paper presents and analyzes a possible layout and optics for the new IRs, with a beta* squeezed down to 15 cm in collision using the ATS scheme*.
* S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for the LHC Upgrade”, these proceedings.

THPZ022

Operation Scheme and Statistics of KEKB

luminosity, injection, sextupole, factory

3735

M. Tanaka
MELCO SC, Tsukuba, Japan
Y. Funakoshi
KEK, Ibaraki, Japan

The KEKB B-Factory(KEKB) started a collision experiment in 1999 and finished in June, 2010. The total operation time of KEKB from fiscal year 2000 was 55657 hours. The breakdowns of operation are physics run 73.8%, machine study 6.8%, machine tuning 4.8%, beam tuning 5.9%, trouble 5.3%, maintenance 2.1% and other 1.3%. The total integrated luminosity was 10⁴¹ fb-1 and the maximum peak luminosity was 21.083 nb-1s⁻¹. To increase the peak and integrated luminosity, the continuous injection scheme, the crab cavities and the skew sextupole magnets were effective. We finished over ten year operation of KEKB in June, 2010.

FRYBA01

The European Spallation Source

linac, target, proton, HOM

3789

S. Peggs
ESS, Lund, Sweden

The principles of the design, and the technical and beam dynamics challenges of the ESS are presented, as well as possible future upgrade options.

Slides FRYBA01 [5.122 MB]