IPAC2013 - List of Keywords (cavity)

Paper	Title	Other Keywords	Page
MOPEA003	Status and Very First Commissioning of the ASTRID2 Synchrotron Light Source	vacuum, quadrupole, lattice, booster	64
	S.P. Møller, N. Hertel, J.S. Nielsen ISA, Aarhus, Denmark
	ASTRID2 is the new 10 nm UV and soft x-ray light source at Aarhus University. It will replace the ageing source ASTRID, which will be used as the full-energy (580 MeV) booster for ASTRID2. An upgrade of the beamlines at ASTRID are presentlytaking place before being transferred to ASTRID2 until the end of 2013. In addition new beamlines and insertion devices are being procured. Presently, ASTRID2 commissioning is alternating with ASTRID operation to continue during 2013. Status in spring 2013 includes operation of most sub-systems resulting in top-up mode operation to 150 mA. The lattice have been qualifies although a re-alignment is planned. The poster will present experiences from the first commissioning and give the status of the project.

MOPEA012	Lifetime Studies at Metrology Light Source and ANKA	optics, electron, scattering, septum	88
	T. Goetsch, J. Feikes, M. Ries, G. Wüstefeld HZB, Berlin, Germany A.-S. Müller KIT, Karlsruhe, Germany
	The Metrology Light Source (MLS), situated in Berlin (Germany) is an electron storage ring operating from 10⁵ MeV to 630 MeV and is serving as the national primary radiation source standard from the near infrared to the vacuum ultraviolet spectral region. In its standard user mode, the lifetime is dominated by the Touschek effect. Measurements and analysis of the Touschek lifetime as a function of beam current and RF-Voltage will be presented and compared to measurements done at the ANKA electron storage ring (Karlsruhe, Germany) which operates at 0.5 to 2.5 GeV. R. Klein et al., Phys. Rev. ST-AB 11, 110701 (2008) ** A.-S. Müller et al., Energy Calibration Of The ANKA Storage Ring, In Proceedings of EPAC 2004

MOPEA018	Feasibility Study of Heavy Ion Storage and Acceleration in the HESR with Stochastic Cooling and Internal Targets	target, ion, simulation, acceleration	106
	H. Stockhorst, R. Maier, D. Prasuhn, R. Stassen FZJ, Jülich, Germany T. Katayama GSI, Darmstadt, Germany
	Stochastic cooling of heavy ions is investigated under the constraint of the present hardware design of the cooling system and RF cavities as well as the given magnet design as foreseen for anti-proton cooling in the HESR of the FAIR facility. A bare uranium beam is injected from the collector ring CR into the HESR at 740 MeV/u. The beam preparation for an internal target experiment with cooling is outlined. The acceleration of the ion beam to 2 GeV/u is studied under the basic condition of the available cavity voltages and the maximum magnetic field ramp rate in the HESR. The cooling simulations include the beam-target interaction due to a Hydrogen and Xenon target. Diffusion due to Schottky and thermal noise as well as intra beam scattering is accounted for. Due to the higher charge states of the ions Schottky particle noise power becomes an important issue. The analysis considers the electronic power limitation to 500 W in case of momentum cooling. Fast Filter cooling is only available if the revolution harmonics do not overlap in the cooling bandwidth. Since overlap occurs for lower energies the application of the Time-Of-Flight (TOF) momentum cooling method is discussed.

MOPEA030	Status of UVSOR-III	injection, undulator, vacuum, sextupole	142
	N. Yamamoto Nagoya University, Nagoya, Japan T. Konomi UVSOR, Okazaki, Japan
	Construction of the Central Japan Synchrotron Radiation (SR) Facility has been completed in the Aichi area of Japan, and the beam commissioning was started in Spring of 2012. Up to now, it is confirmed that the 1.2 GeV storage ring works with 300 mA Top-up mode. The key equipments of the accelerators are a compact electron storage ring with the ability to supply hard X-rays and full energy injectors for the top-up operation. The accelerators consist of an electron storage ring, a booster synchrotron ring, and an injector linac. In this prezentation, the present status of the accelerators are reported.

MOPEA039	Beam Commissioning and Neutron Radiography on a High Current Deuteron RFQ	rfq, neutron, target, ECR	163
	Y.R. Lu, J. Chen, J.E. Chen, S.L. Gao, Z.Y. Guo, F.J. Jia, G. Liu, S.X. Peng, H.T. Ren, W.L. Xia, X.Q. Yan, K. Zhu PKU, Beijing, People's Republic of China S.Q. Liu, S. Wang, J. Zhao, B.Y. Zou State Key Laboratory of Nuclear Physics and Technology, Beijing, Haidian District, People's Republic of China
	Funding: Supported by NSFC 11079001 and Peking University The high current deuteron RFQ has been developed and widely used in many projects, especially for accelerator based neutron source and its application. This paper reviews not only the recent developments in the world wide, also presents the beam dynamics, structure design ,RF full power test, beam commissioning of PKUNIFTY, which is consisted of a high current very compact ECR source, a 201.5MHz four-rod deuteron RFQ, thicker beryllium target and its moderating, collimation and neutron radiography system. RF and beam commissioning with duty cycle of 4% show the RFQ inter-vane voltage reaches 70kV at about 240kW, the delivered deuteron peak beam current is about 12mA at 290kW with the beam transmission of about 60%. The improvement of transmission is going on. The initial neutron radiography commissioning has been carried out. The results will promote the future development of small accelerator based neutron source.

MOPEA040	Study of Geometry Dependent Multipacting of a Superconducting QWR	accelerating-gradient, electron, simulation, vacuum	166
	K. Zhou, X.Y. Lu, X. Luo, S.W. Quan, L. Yang, Z.Y. Yao PKU, Beijing, People's Republic of China
	Funding: The Major Research Plan of National Natural Science Foundation of China A superconducting quarter wave resonator (QWR) of frequency=162.5 MHz and β=0.085 has been designed at Peking University. This paper focus on the multipacting (MP) study for the QWR with CST Particle Studio. The simulation results for the initial designed model reveal that there is no sign of MP with its normal operating accelerating gradients in the range of 6-8 MV/m. The accelerating gradient range that may incur MP is from about 1.4 MV/m to 3.2 MV/m, and the places where MP may be encountered are mainly located at the top part of the QWR. So the effect of different top geometries on MP has also been studied in depth. Our results show that inward convex round roof is better than other round roofs, and plane roofs have an obvious advantage over round roofs on the suppression of MP in general. While considering the optimization of its electromagnetic (EM) design, our initial designed model is also acceptable.

MOPEA045	Performance Optimization and Upgrade of the SSRF Storage Ring	storage-ring, emittance, optics, injection	178
	Z.T. Zhao, B.C. Jiang, Y.B. Leng, S.Q. Tian, L. Yin, W.Z. Zhang SINAP, Shanghai, People's Republic of China
	The SSRF storage ring achieved its design performance goal in 2008, in the following years its performance was optimized and improved, including implementing top-up operation and low emittance lattice configuration as well as other attempts like fast orbit feedback and low alpha mode. In order to meet the requirements of accommodating more beamlines and high demanding performance in its phase-II beamline project, the SSRF storage ring is being upgraded with a design based on superbend based lattice and a third harmonic RF cavity system. This paper presents the main optimization works and the upgrade design considerations on the SSRF storage ring performance.

MOPEA056	Measuring and Improving the Momentum Acceptance and Horizontal Acceptance at MAX III	lattice, electron, vacuum, storage-ring	205
	A. Hansson, Å. Andersson, J. Breunlin, G. Skripka, E.J. Wallén MAX-lab, Lund, Sweden
	Lifetime measurements for varying horizontal scraper positions performed at different RF frequencies suggested a horizontal aperture restriction in the MAX III synchrotron light source. A combination of local orbit distortions and horizontal scraper measurements pinpointed the location of the horizontal aperture restriction to the center of the main cavity straight section. The aperture restriction was determined to be located 10.4 ± 0.3 mm from the beam center. The precise result was achieved by measurements and calculations of the Touschek lifetime as a function of the main cavity voltage. Realignment of the main cavity increased the average lattice momentum acceptance from 0.0116 ± 0.0003 to 0.0158 ± 0.0003 and the horizontal acceptance from 26 ± 2 × 10^-6 m to larger than 44 ± 2 × 10^-6 m. The increase in momentum acceptance increased the lifetime in MAX III by a factor of two.

MOPEA057	Studies of the Electron Beam Lifetime at MAX III	scattering, electron, vacuum, emittance	208
	A. Hansson, Å. Andersson, J. Breunlin, G. Skripka, E.J. Wallén MAX-lab, Lund, Sweden
	MAX III is a 700 MeV 3rd generation synchrotron light source located at the MAX IV Laboratory in Sweden. The lifetime in the storage ring is lower than originally envisaged. From vertical scraper measurements the lifetime contributions at 300 mA stored current have been determined. The lifetime is mainly limited by the Touschek lifetime, which is lower than its design value, whereas the vacuum lifetime is close to the expected value. The low Touschek lifetime is explained by a lower than design emittance ratio and momentum acceptance in the storage ring.

MOPEA061	Operation Experience at Taiwan Light Source	kicker, SRF, diagnostics, injection	220
	Y.-C. Liu, H.H. Chen, H.C. Chen, S. Fann, S.J. Huang, J.A. Li, C.C. Liang, Y.K. Lin, Y.-H. Lin, M.-S. Yeh NSRRC, Hsinchu, Taiwan
	A matrix structure has been implemented for the purpose of successful operation of TLS and continuous progress of Taiwan Photon Source (TPS) construction. A dedicated and flexible manpower distribution has proven it could keep as same performance of TLS operation as possible. We will summarize the machine operation experience at TLS during TPS civil construction period.

MOPFI001	Characterization of a Superconducting Pb Photocathode in a SRF Gun Cavity	cathode, laser, gun, electron	279
	R. Barday, T. Kamps, O. Kugeler, A. Neumann, M. Schmeißer, J. Völker HZB, Berlin, Germany P. Kneisel JLAB, Newport News, Virginia, USA R. Nietubyć NCBJ, Świerk/Otwock, Poland J.K. Sekutowicz DESY, Hamburg, Germany J. Smedley BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Bundesministerium für Bildung und Forschung and Land Berlin. The Pb deposition activity is supported by EuCARD. Photocathodes are a limiting factor for the next generation of ultra-high brightness photoinjector driven accelerators. We studied the behavior of a superconducting Pb cathode in the cryogenic environment of a superconducting rf gun cavity related to the quantum efficiency, its spatial distribution and the work function. Cathode surface contaminations can modify the performance of the photocathodes as well as the gun cavity. We discuss the possibilities to remove these contaminations.

MOPFI002	Results from Beam Commissioning of an SRF Plug-gun Cavity Photoinjector	laser, emittance, cathode, gun	282
	M. Schmeißer, R. Barday, A. Burrill, A. Jankowiak, T. Kamps, J. Knobloch, O. Kugeler, P. Lauinger, A. Neumann, J. Völker HZB, Berlin, Germany P. Kneisel JLAB, Newport News, Virginia, USA R. Nietubyć NCBJ, Świerk/Otwock, Poland J.K. Sekutowicz DESY, Hamburg, Germany I. Will MBI, Berlin, Germany
	Superconducting rf photoelectron injectors (SRF guns) hold the promise to deliver high brightness, high average current electron beam for future lightsources or other applications demanding continuous wave operation of an electron injector. This paper discusses results from beam commissioning of a hybrid Pb coated plug-gun Nb cavity based SRF photoinjector for beam energies up to 3 MeV at Helmholtz-Zentrum Berlin. Emittance measurements and transverse phase space characterization with solenoid-scan and pepperpot methods will be presented.

MOPFI003	SRF Photoinjector Cavity for BERLinPro	cathode, SRF, gun, HOM	285
	A. Neumann, W. Anders, A. Burrill, A. Frahm, T. Kamps, J. Knobloch, O. Kugeler HZB, Berlin, Germany E.N. Zaplatin FZJ, Jülich, Germany
	For the funded BERLinPro project, a 100 mA CW-driven SRF energy recovery linac, a SRF photoinjector cavity has to be developed which delivers a small emittance, 1 mm*mr, high brightness beam while accelerating a high average current within given high power limitations. To achieve these goals the injector is being developed in a three stage approach. In the current design step a cavity shape was developed which fulfills the beam dynamics requirements, implements a high quantum efficiency normal conducting photocathode with the HZDR choke and insert design and allows for beam studies at currents up to 4 mA. This paper will describe the RF design process, higher order mode studies and final mechanical calculations prior to the cavity production.

MOPFI004	The Injector Layout of BERLinPro	emittance, cathode, linac, gun	288
	B.C. Kuske, M. Abo-Bakr, V. Dürr, A. Jankowiak, T. Kamps, J. Knobloch, P. Kuske, S. Wesch HZB, Berlin, Germany
	Funding: The Bundesministerium für Bildung und Forschung (BMBF) and the state of Berlin, Germany. BERLinPro is an Energy Recovery Linac Project running since 2011 at the HZB in Berlin. The key component of the project is the 100mA superconducting RF photocathode gun under development at the HZB since 2010. Starting in 2016 the injector will go into operation providing 6 MeV electrons with an emittance well below 1mm mrad and bunches shorter than 4ps. 2017 the 50MeV linac will be set up and full recirculation is planned for 2018. The injector design including a dogleg merger has been finalized and is described in detail in this paper. Emphasis is laid on the final layout including collimators and diagnostics and performance simulations of two different gun cavities and first tolerance studies.

MOPFI020	Cold Test of the Coaxial Cavity for Thermionic Triode Type RF Gun	gun, resonance, electron, FEL	324
	T. Konstantin, Y.W. Choi, T. Kii, R. Kinjo, K. Masuda, M. Mishima, K. Nagasaki, H. Negm, H. Ohgaki, K. Okumura, M. Omer, S. Shibata, K. Shimahashi, K. Yoshida, H. Zen Kyoto University, Institute for Advanced Energy, Kyoto, Japan
	A thermionic rf gun has several advantages as compared to photocathode gun. Such as low cost, high averaged current and simple operation. However a thermionic rf gun has a significant disadvantage in form of back bombardment effect. The KU-FEL facility is an oscillator type FEL, which uses a thermionic 4.5 cell S-band RF gun for electron beam generation. The back bombardment effect causes increasing current in macropulse, which limits the gain of the FEL. In order to mitigate the current increase we plan to modify thermionic rf gun to triode type rf gun. Therefore an additional rf cavity has been designed. This cavity has separate rf power supply with amplitude and phase control. By this means we can properly adjust the injection of electrons into the main gun body. According to simulations the triode type gun can reduce 80% of back streaming electron energy. The cold tests of the first prototype have revealed deviation from designed values. Based on the tests of the first prototype new prototype with integrated mechanism for resonance tuning has been designed and fabricated. In this work we report the cold test of the redesigned prototype of the coaxial rf cavity. K. Masuda et al. Proceedings of FEL 2006, BESSY Berlin. ** M. Takasaki et al. Proceedings of FEL 2010, Malbö

MOPFI033	Commissioning Results and Progress of a Helium Injector for Coupled RFQ and SFRFQ Project at Peking University	ion, rfq, ion-source, emittance	357
	J. Chen, J.E. Chen, S.L. Gao, Z.Y. Guo, Y.T. Luo, S.X. Peng, H.T. Ren, Z. Wang, Z.H. Wang, W.L. Xia, Y. Xu, A.L. Zhang, T. Zhang, J. Zhao PKU, Beijing, People's Republic of China
	At Peking University (PKU) a new helium injector for coupled radio frequency quadrupole(RFQ) and separated function radio frequency quadrupole(SFRFQ) within one cavity, so called as coupled RFQ & SFRFQ, was designed recently. It will provide a 30keV 20mA He⁺ beam whose emittance is less than 0.15 π.mm.mrad for the accelerator. It is a combination of a 2.45GHz PKU PMECRIS (Permanent Magnet ECRIS) and a 1.16 m long LEBT. Within the 1.16 m LEBT, 2 solenoids, 2 steering magnets, a kicker, a space charge compensation section, a collimator, two vacuum valves, a Faraday cup and an ACCT are installed. The manufacture has been completed and the commissioning is on the way. In this paper we will address the commissioning results and its progress. Haitao Ren, et al., A Helium Injector for Coupled RFQ and SFRFQ Cavity Project at Peking University. Proc. LINAC’12, Paper TUPB034, Israel, 2012

MOPFI044	VHF Gun Research at SINAP	gun, electron, FEL, vacuum	380
	Q. Gu, L. Chen, W. Fang, G.Q. Lin SINAP, Shanghai, People's Republic of China
	The R&D work on the high power THz based on energy recovery linac (ERL) has been carried out in Shanghai Institute of Applied Physics (SINAP). One of the key components for the ERL is the high brightness electron source. The low frequency gun technology has been adopted, by comparing with the SRF gun and DC gun. In this paper, the design and cold test of a 250MHz gun will be presented.

MOPFI045	Studying of Multipacting in Micro-pulse Electron Gun	electron, gun, simulation, resonance	383
	L. Liao, W. Fang, Q. Gu, M. Zhang, M.H. Zhao SINAP, Shanghai, People's Republic of China
	Depending on the complexity of multipacting phenomenon, more works are focused on the occurrence of multipacting in the micro-pulse electron gun. In this paper, the multipacting resonance condition is determined in a reentrant cavity model of the gun. The resonance parameters work as the input for VORPAL simulations in order to achieve a steady state saturation in the cavity. The simulation results showed that the gun can give rise to electrons beam with high currents and short pulses.

MOPFI068	High Repetition Rate Highly Stable S-band Photocathode Gun for the CLARA Project	gun, laser, electron, cathode	437
	B.L. Militsyn, L.S. Cowie, P. Goudket, S.P. Jamison, J.W. McKenzie, K.J. Middleman, R. Valizadeh, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom V.V. Paramonov RAS/INR, Moscow, Russia M.D. Roper STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	Compact Linear Accelerator for Research and Applications (CLARA) is a 250 MeV electron facility which is under development at STFC ASTeC. The CLARA photo-injector is based on a RF photocathode gun operating with metal photocathodes and driven by a third harmonic of Ti: Sapphire laser (266 nm). The injector will be operated with laser pulses with an energy of up to 2 mJ, pulse durations down to 180 fs FWHM and a repetition rate of up to 400 Hz. In order to investigate performance of different photocathodes the gun is equipped with a load-lock system which would allow replacement of the photocathodes. Duration and emittance of electron bunches essentially depends on the mode of operation and vary from 0.1 ps at 20 pC to 5 ps at 200 pC and from 0.2 to 2 mm mrad respectively. Requirements for the stability of beam arrival time at the CLARA experimental area are extremely high and vary from hundreds down to tenths femtoseconds. In the presented article we analyse stability of the guns with 1.5 and 2.5 cell and the beam quality delivered by a gun with coaxial and waveguide coupler and analyse possibility of injection time stabilisation with low level RF and optical feedback system.

MOPME019	Alignment Detection Study using Beam Induced HOM at STF	HOM, dipole, alignment, cryomodule	509
	A. Kuramoto Sokendai, Ibaraki, Japan H. Hayano KEK, Ibaraki, Japan
	STF accelerator using L-band photocathode RF Gun and two superconducting cavities is under operation for R&D of ILC. Electron beam extracted from the RF Gun is accelerated to 40 MeV by two superconducting cavities. Cavity alignment requirements for ILC are less than 300um offset and 300urad tilt with respect to cryomodule. It is necessary to measure their offset and tilt inside of cryomodule. Cavity offset has been already measured by using beam induced HOM at FLASH in DESY. Cavity deformation during assembly and by cooling contraction has not been examined yet. We measured HOM signals to detect their tilt and bending. TE111-6 which has high impedance is used to estimate cavity offset. To find cavity tilt and bending, we selected pi over nine mode in the first dipole passband (TE111-1) and beam pipe modes. From information of TE111-1 which has maximum radial electric field in the middle cell, we can get electrical center of middle cell. At beam pipes, electrical center can be found by using beam pipe modes. Combinations of these electrical centers tell us cavity tilt and bending. We will present results of these TE111-1 and beam pipe mode together with beam trajectory information.

MOPME026	Beam Monitor Layout for Future ACS Section in J-PARC Linac	linac, DTL, beam-transport, monitoring	529
	A. Miura, M. Ikegami, H. Oguri JAEA/J-PARC, Tokai-mura, Japan
	In J-PARC Linac, an energy and intensity upgrade project has started since 2009 using Annular Coupled Structure (ACS) cavities. With this upgrade, the design peak current will be increased from the present 30 mA to 50 mA, and the energy from 181 MeV to 400 MeV. Along with these significant upgrades of the beam parameters, beam monitors should be followed. Also, the bunch shape monitor and new beam loss monitoring system will be employed for the new beam line. Newly fabricated devices will be delivered in the ACS beam line. And beam monitor layout of the upstream and downstream of ACS beam line will be modified. In this paper, we introduce the development of the beam diagnostic devices for the project and the new designed beam monitor layout.

MOPME040	Cavity-based Multi-parameter Beam Diagnostics at HLS	quadrupole, emittance, diagnostics, gun	559
	Q. Luo, B.G. Sun USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Natural Science Foundation of China (11005106) Recent developments of the fourth generation light sources needs precious control of beam parameters, such as beam position, transverse emittance, beam density, bunch length, etc.. Non-destructive on-line beam diagnostic methods are then required. As an example, the cavity beam multi-parameter monitor system designed for the HLS photocathode RF electron gun consists of a beam position monitor, a beam quadrupole moment monitor and a beam density and bunch length monitor. 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. Beam quadrupole moment monitor system consists of a square pill-box quadrupole moment cavity, a cylindrical pill-box reference cavity and a waveguide coupling network. TM0n0 modes of cavity can be used to work out beam density and bunch length simultaneously. To simplify the design and suppress the whole system here, we use the reference cavity of beam position monitor as beam density and bunch length signal pick-up.

MOPME051	Development of Cavity Beam Position Monitor System	FEL, simulation, coupling, electron	586
	B.P. Wang, Y.B. Leng, Y.B. Yan, L.Y. Yu, R.X. Yuan, W.M. Zhou SINAP, Shanghai, People's Republic of China
	Shanghai soft X-ray free electron laser (SXFEL) facility requires beam position resolution better than 1 μm in the undulator sections. Cavity BPM system, feasible in obtaining sub micron position resolution, has been developed to achieve the goal. Two cavity prototypes with high Q and low Q were designed and fabricated. The relevant dedicated electronic, which could cover the two types of cavity BPMs, also have been developed. Fast fourier transform (FFT) and digital down converted based algorithms were implemented. The beam test of the whole system has been scheduled on the Shanghai deep ultraviolet (SDUV) FEL facility. The cavity design, electronic architecture, achieved performance during beam test will be presented.

MOPME058	DEVELOPMENT OF A CAVITY-TYPE BEAM POSITION MONITORS WITH HIGH RESOLUTION FOR ATF2	dipole, simulation, electron, extraction	604
	S.W. Jang, E.-S. Kim KNU, Deagu, Republic of Korea Y. Honda, T. Tauchi, N. Terunuma KEK, Ibaraki, Japan
	We have developed a high resolution beam position monitors for ATF2 at KEK, which is an accelerator test facility for International Linear Collider(ILC). The main goals of ATF2 are achievement of 37nm beam size and 2nm beam position resolution for beam stabilization. For these goals, low-Q IP-BPM(Interaction Point Beam Position Monitor) with latency of 20 ns are being developed. In this paper, we will describe about design of Low-Q IP-BPM, the basics test results as RF test and BPM sensitivity test. Electronics for Low-Q IP-BPM will be also described.

MOPME073	Measurement of Schottky-like Signals from Linac Bunched Hadron Beams for Momentum Spread Evaluation	linac, synchrotron, pick-up, bunching	649
	P. Kowina, P. Forck, R. Singh GSI, Darmstadt, Germany F. Caspers CERN, Geneva, Switzerland R. Singh TEMF, TU Darmstadt, Darmstadt, Germany
	We present a novel method for the measurement of Linac beam parameters in the longitudinal phase space. The longitudinal momentum spread can be evaluated by means of Schottky type signal analysis of bunched beams. There is a close similarity between a repetitive Linac bunch train and a circulating beam with a single short batch in a large machine like the LHC. A dedicated longitudinal cavity pick-up was used in the Linac where resonance frequency and Q-value were carefully selected in order to get an optimum compromise between the unavoidable coherent signal and the desired incoherent part of the beam spectrum. A time domain gating similar to the 4.8 GHz LHC Schottky front-end is applied. As a cross-check of the validity of the interpretation in terms of momentum spread, the Linac beam is analyzed in the downstream synchrotron using standard Schottky methods. In principle, this approach can be understood as an extension of Schottky analysis for circular machines with a perfect “mixing” between subsequent bunch trains. This contribution describes the test set-up and discusses the results of the measurements with a heavy ion beam.

MOPWA052	Short Range Wakefield Measurements of High Resolution RF Cavity Beam Position Monitors at ATF2	wakefield, quadrupole, simulation, extraction	792
	J. Snuverink, S.T. Boogert, F.J. Cullinan, Y.I. Kim, A. Lyapin JAI, Egham, Surrey, United Kingdom K. Kubo, T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan G.R. White SLAC, Menlo Park, California, USA
	Cavity beam position monitors (CBPM) have been used in several accelerator facilities and are planned to be used in future accelerators and light sources. High position resolution up to tens of nanometres has been achieved, but short range wakefields are a concern, especially for small beam emittances. This paper presents the wakefield calculations as well as the first measurements of the CBPM-generated short range wakefields performed at the Accelerator Test Facility (ATF2).

MOPWA055	Status of Higher Order Mode Beam Position Monitors in 3.9 GHz Superconducting Accelerating Cavities at FLASH	HOM, wakefield, dipole, diagnostics	798
	P. Zhang, R.M. Jones, I.R.R. Shinton UMAN, Manchester, United Kingdom N. Baboi, P. Zhang DESY, Hamburg, Germany T. Flisgen, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: This work was partially funded by the European Commission under the FP7 Research Infrastructures grant agreement No.227579. Higher order mode (HOM) beam position monitors (BPM) are being developed for the 3.9GHz third harmonic superconducting accelerating cavities at FLASH. The transverse beam position in a cavity can be determined utilizing beam-excited HOMs based on dipole components. The existing couplers used for HOM suppression provide the necessary signals. The diagnostics principle is similar to a cavity BPM, but requires no additional vacuum instruments on the linac. The challenges lie in the dense HOM spectrum arising from couplings of the majority HOMs amongst the four cavities in the cryo-module. HOMs with particularly promising diagnostics features were evaluated using various devices with various analysis methods. After careful theoretical and experimental assessment of HOMs, multi-cavity modes at ~5GHz were chosen to provide a global position over the complete module with superior resolution (~20μm) while trapped modes at ~9GHz provide local position in each cavity with comparable resolution (~50μm). A similar HOM-BPM system is planned for the European XFEL 3.9GHz module with 8 cavities. This paper reviews both the current status and the future prospects of HOM-BPMs in 3.9GHz cavities.

MOPWA058	Cavity Beam Position Monitor at Interaction Point Region of Accelerator Test Facility 2	feedback, quadrupole, optics, focusing	807
	Y.I. Kim, D.R. Bett, N. Blaskovic Kraljevic, P. Burrows, G.B. Christian, M.R. Davis, A. Lyapin JAI, Oxford, United Kingdom S.T. Boogert Royal Holloway, University of London, Surrey, United Kingdom J.C. Frisch, D.J. McCormick, J. Nelson, G.R. White SLAC, Menlo Park, California, USA Y. Honda, T. Tauchi, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	Nanometre resolution cavity beam position monitors (BPMs) have been developed to measure the beam position and linked to a feedback system control the beam position stability within few nanometres in the vertical direction at the focus, or interaction point (IP), of Accelerator Test Facility 2 (ATF2). In addition, for feedback applications a lower-Q and hence faster decay time system is desirable. Two IPBPMs have been installed inside of IP chamber at the ATF2 focus area. To measure the resolution of IPBPMs two additional C-band cavity BPMs have been installed one upstream and one downstream of the IP. One cavity BPM has been installed at an upstream image point of IP. The performance of the BPMs is discussed and the correlation between IP and image point positions is presented along with a discussion of using these BPMs for position stabilisation at the IP.

MOPWA064	Microwave Resonator Diagnostics of Electron Cloud Density Profile in High Intensity Proton Beam	electron, proton, vacuum, simulation	825
	Y.-M. Shin, J. Ruan, C.-Y. Tan, J.C.T. Thangaraj, R.M. Zwaska Fermilab, Batavia, USA
	We have developed an novel technique to accurately estimate the density of dilute electron clouds emitted from high intensity proton beams. The strong phase shift enhancement from multiple reflections of standing microwaves in a resonating beam pipe cavity has been demonstrated with numerical modeling using dielectric approximation and e S-parameter measurements. The equivalent dielectric simulation showed a ~ 10 times phase shift enhancement (Pi-mode, 1.516 GHz) with the cavity beam pipe compared to the waveguide model. The position-dependence of the technique is investigated by overlapping the field distributions of harmonic resonances. The simulation with various positions of dielectric insertions confirmed that resonance peaks in phase-shift spectra corresponding to the relative distance between field-nodes and electron cloud position, which allows for one-dimensional mapping. Preliminary experimental studies based on a bench-top setup confirm the results of the simulation showing that thicker reflectors enhance the phase-shift measurement of the electron cloud density.

MOPWA070	Beam Position Monitor within the Cornell Energy Recovery Linac Cavity Assembly	HOM, coupling, pick-up, RF-structure	840
	M.G. Billing, M. Liepe, V.D. Shemelin, N.R.A. Valles CLASSE, Ithaca, New York, USA
	In an energy recovery Linac (ERL) the low energy beam is very sensitive to deflections due to the RF fields as it passes through the accelerator cavities. Therefore, to avoid the possible effects of beam breakup, it will be important to determine the optimum transverse position for the beam within the first several sets of cavity cells in the cryostat assembly and to maintain this position over long periods. As a result a beam position monitor (BPM) has been designed to be located between the higher-order modes (HOM) loads and the seven-cell RF structures. This BPM’s design reduces the coupling of RF power from the fundamental mode and HOMs into the BPM, while maintaining acceptable position sensitivity and resolution. We analyzed the coupling of the probe to the HOMs of realistically shaped cavities by generating geometries for hundreds of cavities having small shape variations from the nominal dimensions consistent with present machining tolerances, and solved for their monopole and dipole spectra. Our results show that the peak, dissipated power within BPM cables, which pass through the cryostat, is well within the permissible levels.

MOPWO002	PTCC: New Beam Dynamics Design Code for Linear Accelerators	linac, space-charge, simulation, plasma	882
	Y. N. Nour El-Din, T.M. Abuelfadl Cairo University, Giza, Egypt
	Funding: Work supported by the Egyptian Science and Technology Development Fund (STDF) No. 953. A fast and accurate beam dynamics design code, named PTCC (Particle Tracking Code in C) is developed to simulate particles dynamic in linear accelerators. PTCC solves the relativistic equations of motion for the macro-particles when subjected to electromagnetic fields excited in RF cavities. The self-fields of the particles are also part of the electromagnetic fields through which the particles are tracked. Self-fields are calculated using a modified 2D cylindrically symmetric mesh based method, making use of beam and field symmetry to provide fast simulation. The code has been benchmarked with the well known code ASTRA which is used mainly in simulations of next generation FEL linacs. PTCC provides a new tool for designing buncher section of linear accelerators that convert DC beam into bunches. New buncher design tool and benchmark results of PTCC with ASTRA are presented.

MOPWO003	Multibunch Tracking Code Development to Account for Passive Landau Cavities	electron, damping, impedance, radiation	885
	M. Klein, R. Nagaoka SOLEIL, Gif-sur-Yvette, France
	The MAX IV 3 GeV storage ring will achieve an ultra-low horizontal emittance of 0.24 nm rad by using a multibend achromat lattice. Passive harmonic cavities are introduced to relax the Touschek-lifetime and intrabeam scattering issues as well as fight collective beam instabilities via Landau damping. Since instabilities occur during injection, when the passive harmonic cavity potential is also time varying, it became important to simulate this transient process. The most promising approach was considered to be multibunch tracking which also allows for an arbitrary filling pattern. Since every bunch is represented by numerous macroparticles, internal motions as well as microstructures in the charge distribution can be followed.

MOPWO006	Eigenmode Computation for the GSI SIS18 Ferrite Cavity	resonance, heavy-ion, ion, synchrotron	894
	K. Klopfer, W. Ackermann, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Supported by GSI At the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt the heavy-ion synchrotron SIS18 is operated to further accelerate stable nuclei of elements with different atomic numbers. Two ferrite-loaded cavity resonators are installed within this ring. During the acceleration phase their resonance frequency has to be adjusted to the revolution frequency of the heavy-ions to reflect their increasing speed. To this end, dedicated biased ferrite-ring cores are installed inside the cavities for a broad frequency tuning. By properly choosing a suited bias current, the differential permeability of the ferrite material is modified, which finally enables to adjust the eigenfrequency of the resonator system. Consequently, the actual resonance frequency strongly depends on the magnetic properties of the ferrites. The goal of the current study is to numerically determine the lowest eigensolutions of the GSI SIS18 ferrite-loaded cavity. For this purpose, a new solver based on the Finite Integration Technique has been developed.

MOPWO007	Numerical Calculation of Electromagnetic Fields in Acceleration Cavities Under Precise Consideration of Coupler Structures	dipole, electromagnetic-fields, impedance, resonance	897
	C. Liu, W. Ackermann, W.F.O. Müller, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by BMBF under contract 05H12RD5 The acceleration with superconducting radio frequency cavities requires dedicated couplers to transfer energy from the radio frequency source to the beam. Simultaneously, higher order mode couplers are installed to effectively suppress parasitic modes. Therefore, the numerical eigenmode analysis based on real-valued variables is no longer suitable to describe the dissipative acceleration structure. At the Computational Electromagnetics Laboratory (TEMF) a robust parallel eigenmode solver to calculate the eigenmodes in the lossy acceleration structure is available. This eigenmode solver is based on complex-valued finite element analysis and utilizes basis functions up to the second order on curved tetrahedral elements to enable the high precision elliptical cavity simulations. The eigenmode solver has been applied to the TESLA 1.3 GHz accelerating cavity to determine the resonance frequency, the quality factor and the corresponding field distribution for all 192 eigenmodes up to the 5th dipole passband (3.12 GHz).

MOPWO008	Eigenmode Computation for Elliptical Cavities Subject to Geometric Variation using Perturbative Methods	simulation, factory, higher-order-mode, SRF	900
	K. Brackebusch, 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 05K10H. Parametric studies of geometric variations are an essential part of the performance optimization and error estimation in the design of accelerator cavities. Using common eigenmode solvers the analysis of intentional and undesired geometric perturbations tend to be very extensive since any geometric variation involves an entire eigenmode recomputation. Perturbative methods constitute an efficient alternative for the computation of a multitude of moderately varying geometries. They require a common eigenmode computation of solely one (so called unperturbed) geometry and allow for deriving the eigenmodes of similar but modified (so called perturbed) geometries from these unperturbed eigenmodes. In [],[] the practicability of perturbative methods was already proven by means of simple cavity geometries. In this paper we investigate the applicability and efficiency for practically relevant cavities. For this, basic geometric parameters of elliptical cavities are varied and the respective eigenmodes are computed by using perturbative as well as common methods. The accuracy of the results and the computational effort of the different methods are compared. K. Brackebusch, H.-W. Glock, U. van Rienen, WEPPC096, IPAC 2011 **K. Brackebusch, U. van Rienen, MOPPC062, IPAC 2012

MOPWO010	Machine Protection Studies for a Crab Cavity in the LHC	simulation, beam-losses, luminosity, collimation	906
	B. Yee-Rendon, R. Lopez-Fernandez CINVESTAV, Mexico City, Mexico T. Baer, J. Barranco, R. Calaga, A. Marsili, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland
	Funding: US-LARP and CONACYT Crab cavities (CCs) apply a transverse kick that rotate the bunches so as to have a head-on collision at the interaction point (IP). Such cavities were successfully used to improve the luminosity of KEKB. They are also a key ingredient of the HL-LHC project to increase the luminosity of the LHC. As CCs can rapidly change the particle trajectories, machine protection studies are required to assess the beam losses due to fast CC failures. In this paper, we discuss the effect of rapid voltage or phase changes in a CC for the HL-LHC layout using measured beam distributions from the present LHC.

MOPWO053	Evolution of the Tracking Code PLACET	wakefield, simulation, linac, collider	1014
	A. Latina, Y.I. Levinsen, D. Schulte CERN, Geneva, Switzerland J. Snuverink JAI, Egham, Surrey, United Kingdom
	The tracking code PLACET simulates beam transport and orbit corrections in linear accelerators. It incorporates single- and multi-bunch effects, static and dynamic imperfections. A major restructuring of its core has resulted in an improvement in its modularity, with some immediate advantages: its tracking core, which is one of the fastest available for this kind of simulations, is now interfaced toward three different scripting languages to offer great simulation capabilities: Tcl/Tk, Octave and Python. These three languages provide access to a vast library of scientific tools, mechanisms for parallel computing, and access to Java interfaces for control systems (such as that of CTF3). Also, new functionalities have been added: parallel tracking to exploit modern multicore CPUs, the possibility to track through the interaction region in presence of external magnetic fields (detector solenoid) and higher order imperfections in magnets. PLACET is currently used to simulate the CLIC Drive Beam, the CLIC Main Beam, CTF3, FACET at SLAC, and ATF2 at KEK.

TUYB102	Summary of the ILC R&D and Design	positron, electron, linac, damping	1101
	B.C. Barish CALTECH, Pasadena, California, USA
	This talk should provide a summary of the main activities of ILC-GDE since 2005, and an overview of the Technical Design Report with prospects for the next steps for the future.
	Slides TUYB102 [6.544 MB]

TUOCB103	Quasi Traveling Wave Side Couple RF Gun for SuperKEKB	gun, emittance, focusing, cathode	1117
	T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou KEK, Ibaraki, Japan
	We are developing a new RF gun for SuperKEKB. High charge low emittance electron and positron beams are required for SuperKEKB. We will generate 7.0 GeV electron beam at 5 nC 20 mm-mrad by J-linac. In this linac, a photo cathode S-band RF gun will be used as the electron beam source. For this reason, we are developing an advanced RF gun. We have tested a Disk and Washer (DAW) type RF gun. Additionally, another new RF gun which has two side coupled standing wave field is developed. We call it quasi traveling wave side couple RF gun. This gun has a strong focusing field at the cathode and the acceleration field distribution also has a focusing effect. The design of RF gun and experimental results will be shown.
	Slides TUOCB103 [2.959 MB]

TUODB101	Studies on An S-band Bunching System with Hybrid Buncher	bunching, linac, electron, gun	1120
	S. Pei, O. Xiao IHEP, Beijing, People's Republic of China
	Generally, a standard bunching system is composed by a SW pre-buncher, a TW buncher and a standard accelerating section. However, there is one way to simplify the whole system to some extent by using the hybrid buncher, which is a combined structure of the SW pre-buncher and the TW buncher. Here the beam dynamics studies on an S-band bunching system with hybrid buncher is presented, simulation results shows that similar beam performance can be obtained at the linac exit by using this kind of bunching system rather than the standard one. In the meantime, the structure design of the hybrid buncher is also described. Furthermore, the standard accelerating section can also be integrated with the hybrid buncher, this can further simplify the bunching system and lower the construction cost.
	Slides TUODB101 [22.120 MB]

TUOAB202	ILSF, A Third Generation Light Source Laboratory in Iran	storage-ring, synchrotron, dipole, quadrupole	1137
	J. Rahighi, M.R. Khabazi IPM, Tehran, Iran E. Ahmadi, H. Ajam, M. Akbari, S. Amiri, A. Babaei, J. Dehghani, R. Eghbali, J. Etemad Moghadam, S. Fatehi, M. Fereidani, H. Ghasem, A. Gholampour, A. Iraji, M. Jafarzadeh, B. Kamkari, S. Kashani, P. Khodadoost, H. Khosroabadi, M. Moradi, H. Oveisi, S. Pirani, M. Rahimi, M. Razazian, A. Sadeghipanah, F. Saeidi, R. Safian, E. Salimi, Kh.S. Sarhadi, O. Seify, M.Sh. Shafiee, A. Shahveh, A. Shahverdi, D. Shirangi, E.H. Yousefi ILSF, Tehran, Iran D. Einfeld CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	The Iranian Light Source Facility (ILSF) project is a first large scale accelerator facility which is currently under planning in Iran. The circumference of the storage ring is 297.6 m with the energy of 3 GeV. The facility will be built on a land of 100 hectares area in the city of Qazvin, located 150 km West of Tehran. The city is surrounded by many universities, research centers and industrial companies. The design and construction of prototype items such as radio frequency solid state amplifier, dipole magnets, highly stable magnet power supplies and girders have already begun. A low field H-type dipole magnet with the central field of 0.5T at the gap of 34mm and length of 500mm was built and tested in site. Also a prototype storage ring quadrupole with a 18 T/m gradient and 233 iron length is in now in fabrication process. Site selection studies, including geotechnical and seismological measurements are being performed. Conceptual Design Report, CDR, as the first milestone of the project has been published on October 2012.
	Slides TUOAB202 [5.173 MB]

TUODB201	Recent Progress on the Development of a High Gradient RF System using High Impedance Magnetic Alloy, FT3L	impedance, acceleration, synchrotron, controls	1152
	C. Ohmori, K. Hara, K. Hasegawa, M. Toda, M. Yoshii KEK, Ibaraki, Japan M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-mura, Japan
	An upgrade project of J-PARC MR (Main Ring) includes developments of high gradient RF cavities and magnet power supplies for high repetition rate. A dedicated production system for high impedance magnetic alloy (FT3L) cores was assembled in J-PARC. This setup demonstrated that we can produce material with two times higher muQf product compared to the cores used for present cavities. And, the new results also show up to 20% higher impedance than the 2011 production with the former setup. In this summer, the system will be used for mass production of 200 FT3L cores for J-PARC MR. The cores produced in 2011 are already used for standard machine operation. The operation experience shows that the power loss in the cores was reduced significantly as expected. The scenario describing the upgrade plan of MR and the cavity replacements is reported. By the replacement plan, the total acceleration voltage will be almost doubled, while the number of RF stations remains the same.
	Slides TUODB201 [5.105 MB]

TUODB202	Experiment and Numerical Simulation Results of Plasma Window	plasma, simulation, vacuum, cathode	1155
	K. Zhu, S. Huang, Y.R. Lu, B.L. Shi PKU, Beijing, People's Republic of China
	Funding: Supported by NSFC 91026012 A windowless vacuum seal technique has been widely researched and designed, which can connect high pressure cavity to a vacuum condition with rather little thickness of material. As a result, it will reduce most interaction with the particle beam penetrating through comparing to that of foil window. It is desired extensively in experiments using high-intensity heavy ion beams which will break foil window in a short time or in experiments which require the injecting beams with mono-energy and high purity for example. In this work, we study the plasma window in argon which is used as a windowless vacuum sealing device. A numerical 2D FLUENT-based magneto-hydrodynamic model has been developed to investigate the physical reasons of high pressure difference in plasma window. Further, preliminary experimental results are presented and discussed.
	Slides TUODB202 [2.180 MB]

TUPEA003	Components for CW and LP Operation of the XFEL Linac	cryomodule, linac, HOM, cathode	1164
	J.K. Sekutowicz DESY, Hamburg, Germany
	The European XFEL will use superconducting TESLA cavities operating with 650 μs long bunch trains. With 220 ns bunch spacing and 10 Hz RF-pulse repetition rate, up to 27000 high quality bunches/s will be delivered to insertion devices generating unprecedented high average brilliance photon beams at very short wavelength. While many experiments can take advantage of full bunch trains, others prefer an increased intra-pulse distance of several μ-seconds between bunches, or short bursts with a kHz repetition rate. In this contribution, we discuss progress in the R&D program for a future upgrade of the European XFEL linac, to operation in the continuous wave (cw) and long pulse (lp) mode, which will allow for much more flexibility in the electron and photon beam time structure. Modifications and cw tests of XFEL cryomodules, recent tests result of the SRF injector, test of the second prototype of 120 kW IOT are presented. In addition, computer modeling of the cw-operating TESLA-like cavity with modified HOM couplers is briefly discussed.

TUPEA013	Present Status of Mid-infrared Free Electron Laser Facility in Kyoto University	FEL, gun, electron, undulator	1190
	H. Zen, Y.W. Choi, H. Imon, M. Inukai, T. Kii, R. Kinjo, T. Konstantin, K. Masuda, K. Mishima, H. Negm, H. Ohgaki, K. Okumura, M. Omer, S. Shibata, K. Shimahashi, K. Yoshida Kyoto University, Institute for Advanced Energy, Kyoto, Japan
	A Mid-Infrared Free Electron Laser (MIR-FEL) facility named as KU-FEL has been constructed for energy science in Institute of Advanced Energy, Kyoto University. The accelerator of KU-FEL consists of an S-band 4.5-cell thermionic RF gun, a Dog-leg section for energy filtering, a 3-m traveling-wave type accelerator tube, 180-degree arc section for bunch compression and a hybrid undulator. We have already succeeded in lasing of the FEL from 5.5 to 14.5 micro-meter. Present status and recent activity for the FEL development will be presented in the conference. H. Zen, et al., Infrared Physics & Technology, vol.51, 382-385.

TUPEA030	High Brightness and Fully Coherent X-ray Pulses from XFELO Seeded High-gain FEL Schemes	FEL, radiation, electron, undulator	1214
	H.X. Deng, C. Feng SINAP, Shanghai, People's Republic of China
	The successful operation of the hard x-ray self-seeding experiment at the LCLS opens the era of fully coherent hard x-ray free electron lasers (FELs). However, the shot-to-shot radiation fluctuation is still a serious issue. In this paper, high-gain, single-pass x-ray FEL schemes seeded by the narrow bandwidth radiation signal from an x-ray FEL oscillator were proposed and investigated, which are expected to generate high brightness, fully coherent and stable x-ray pulse. A simple model has been developed to figure out the temporal and the spectral structures of the output pulses in x-ray FEL oscillator. And options using two synchronized accelerators and using one accelerator were considered, respectively.

TUPEA043	Linac Design for Nuclear Data Measurement Facility	linac, neutron, electron, target	1229
	M. Zhang, W. Fang, Q. Gu, X. Li SINAP, Shanghai, People's Republic of China
	Pulsed neutrons based on an electron linear accelerator (linac) are effective for measuring energy dependent cross-sections with high resolution by using the time-of-flight (TOF) technique. In this paper, we describe the 15-MeV linac design for the Nuclear Data project in Shanghai Institute of Applied Physics (SINAP). The linac has three operating modes and the maximum average power is 7.5kW. We describe the characteristics of the linac and the study of the beam dynamics is also presented.

TUPEA044	The Design of Control System for the Optical Cavity Adjuster of a FEL-THz Source	controls, FEL, electron, undulator	1232
	X. Liu, Q. Fu, B. Qin, P. Tan, C. Wang, Y.Q. Xiong, J. Yang, H. Zeng HUST, Wuhan, People's Republic of China
	The optical cavity adjuster is an important sub-system in a FEL-THz source, which is used to adjust the position and angle of the optical cavity with a high precision. In view of the requirements of the optical cavity adjuster of the FEL-THz source, this paper presents the design of the control system of the optical cavity adjuster. The design of the control system based on a PC and a motion controller is adopted. The motion controller controls high-precision linear stage to adjust linear direction and picomotors are controlled to enable the adjustment of roll and yaw. According to relevant calculation, the range of linear direction and the accuracy can be reached at ±3mm and 0.2~0.5μm; the range of the adjustment of roll and yaw and the accuracy can be reached at ±2° and 20″. In summing up it can be stated that the design meets the requirements and it also lays the foundation for engineering on developing the optical cavity adjuster.

TUPEA068	Wake-field Reduction in Hybrid Photonic Crystal Accelerator Cavities	wakefield, lattice, dipole, simulation	1289
	D. A. Rehn Colorado University at Boulder, Boulder, Colorado, USA C.A. Bauer, J.R. Cary, G.R. Werner CIPS, Boulder, Colorado, USA J.R. Cary, C.D. Zhou Tech-X, Boulder, Colorado, USA
	Funding: This work is supported by the U.S. Dept. of Energy, grant DE-FG02-04ER41317. Photonic crystals (PhCs) have attractive properties for manipulating electromagnetic radiation. In one application, PhCs are composed of a number of dielectric rods that can be arranged to make an accelerator cavity. These structures trap an accelerating mode and allow higher order modes to propagate out. Previous work showed that PhC structures allow excitation of unwanted transverse wake-fields that can disrupt the beam and limit luminosity levels. This work focuses on optimizing PhC cavities to reduce transverse wake-fields by minimizing the Q-factor of unwanted modes, while keeping the Q-factor of the accelerating mode high. The transverse wake-fields in the new optimized structures are compared with previously optimized structures and the CLIC cavity with HOM damping.

TUPFI001	High Luminosity LHC Matching Section Layout vs Crab Cavity Voltage	optics, injection, luminosity, quadrupole	1328
	B. Dalena CEA/IRFU, Gif-sur-Yvette, France A. Chancé, J. Payet CEA/DSM/IRFU, France R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland
	Funding: The research leading to these results has received funding from the European Commission under the FP7 project HiLumi LHC, GA no. 284404, co-funded by the DoE, USA and KEK, Japan. In the framework of the HL-LHC Upgrade project we present a new possible variant for the layout of the LHC matching section located in the high luminosity insertions. This layout is optimized to reduce the demand on the voltage of the crab cavities, while substantially improving the optics squeeze-ability, both in ATS [1] and non-ATS mode. These new layout will be described in details together with its performance figures in terms of mechanical acceptance, chromatic properties and optics flexibility. [1] S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI023	Optics Design and Lattice Optimisation for the HL-LHC	optics, luminosity, quadrupole, lattice	1385
	B.J. Holzer, R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland R. Appleby, S. Kelly, M.B. Thomas, L.N.S. Thompson UMAN, Manchester, United Kingdom A.V. Bogomyagkov BINP SB RAS, Novosibirsk, Russia A. Chancé CEA, Gif-sur-Yvette, France B. Dalena CEA/IRFU, Gif-sur-Yvette, France A. Faus-Golfe, J. Resta IFIC, Valencia, Spain K.M. Hock, M. Korostelev, L.N.S. Thompson, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom C. Milardi INFN/LNF, Frascati (Roma), Italy J. Payet CEA/DSM/IRFU, France A. Wolski The University of Liverpool, Liverpool, United Kingdom
	Funding: The HiLumi LHC Design Study is included in the High Luminosity LHC project and is partly funded by the European Commission within the Framework Programme 7 Cap. Spec. Progr, Grant Agreement 284404. The luminosity upgrade project of the LHC collider at CERN is based on a strong focusing scheme to reach smallest beam sizes at the collision points. Depending on the available magnet technology (Nb3Sn or NbTi) a number of beam optics has been developed to define the specifications for the new super conducting quadrupoles. In the context of the optics matching new issues have been addressed and new concepts have been used: Quadrupole strength flexibility and chromatic corrections have been studied, as well as the influence of quadrupole fringe fields. The lattice has been optimised including the needs of the foreseen crab cavities and the transition between injection and low β optics had to guarantee smooth gradient changes over a wide range of β* values. Tolerances on misalignments and power converter ripple have been re-evaluated. Finally the combination of the quadrupole strengths in the high luminosity matching sections with those in the neighboring sectors is explained, a key concept of the ATS to reach smallest β* values. This paper presents the results obtained within the HiLumi collaboration Task 2.2 and summarises the main parameters of the project.

TUPFI053	Transient Beam Loading Effects in Gas-filled RF Cavities for a Muon Collider	plasma, ion, beam-loading, electron	1463
	M. Chung, A.V. Tollestrup, K. Yonehara Fermilab, Batavia, USA B.T. Freemire IIT, Chicago, Illinois, USA
	Funding: Research supported by the U.S. Department of Energy. A gas-filled RF cavity can be an effective solution for the development of a compact muon ionization cooling channel. One possible problem expected in this type of cavity is the dissipation of significant RF power through the beam-induced plasmas accumulated inside the cavity (plasma loading). In addition, for the higher muon beam intensity, the effects of the beam itself on the cavity fields in the accelerating mode are non-negligible (beam loading). These beam-cavity interactions induce a transient phase which may be very harmful to the beam quality. In this study, we estimate the transient voltage in a gas-filled RF cavity with both the plasma and conventional beam loading and discuss their compensation methods.

TUPFI064	Beam Induced Plasma Dynamics in a High Pressure Gas-Filled RF Test Cell for use in a Muon Cooling Channel	electron, ion, plasma, proton	1496
	B.T. Freemire, P.M. Hanlet, Y. Torun IIT, Chicago, Illinois, USA M. Chung, M.R. Jana, M.A. Leonova, A. Moretti, T.A. Schwarz, A.V. Tollestrup, K. Yonehara Fermilab, Batavia, USA M.G. Collura Politecnico di Torino, Torino, Italy R.P. Johnson Muons. Inc., USA
	Filling an RF cavity with a high pressure gas prevents breakdown when the cavity is place in a multi-Tesla external magnetic field. The choice of hydrogen gas provides the additional benefit of cooling a beam of muons. A beam of particles traversing the cavity, be it muons or protons, ionizes the gas, creating an electron-ion plasma which absorbs energy from the cavity. The ionization rate can be calculated from a beam intensity measurement. Energy loss measurements indicate the loading per RF cycle per electron-ion pair range from 10^-18 to 10^-16 Joules in pure hydrogen, and 10^-20 to 10^-18 Joules when hydrogen is doped with dry air. The addition of an electronegative gas (oxygen) has been observed to reduce the lifetime of ionization electrons in the cavity to below 1 nanosecond. Additionally, the recombination rate of electrons and hydrogen ions has been measured to be on the order of 10^-6 cubic centimeters per second. The recombination mechanism and hydrogen ion species, along with the three-body attachment process of electrons to oxygen, will be discussed.

TUPFI065	Muon Ionization Cooling Experiment Step VI	coupling, emittance, vacuum, status	1499
	D. Rajaram Illinois Institute of Technology, Chicago, Illinois, USA P. Snopok IIT, Chicago, Illinois, USA
	The Muon Ionization Cooling Experiment (MICE) is a demonstration experiment to prove the viability of cooling a beam of muons for use in a Neutrino Factory and Muon Collider. The ultimate Step VI configuration of the MICE cooling channel, a section of the one proposed in the Neutrino Factory Study II, will demonstrate a 10% reduction in transverse beam emittance measured at the level of 1%. This requires measuring emittance to 0.1%. This measurement will be made using all beam line elements present in the MICE Step IV configuration with the addition of two low-Z absorber modules and two RF-Coupling Coil (RFCC) modules. The RFCC modules each contain four normal-conducting low frequency (201 MHz) RF cavities with a guiding magnetic field provided by a large diameter coupling coil. Each of these cavities will require approximately 1 MW of RF power in a 1 ms pulse at a rate of 1 Hz. The experiment can explore a variety of combinations of momentum, beta function, magnetic field flip or non-flip configurations that will prove precious in the design of future cooling channels. The current status and progress toward Step VI are discussed.

TUPFI068	High Power Tests of Alumina in High Pressure RF Cavities for Muon Ionization Cooling Channel	pick-up, collider, resonance, klystron	1508
	L.M. Nash University of Chicago, Chicago, Illinois, USA G. Flanagan, R.P. Johnson, F. Marhauser, J.H. Nipper Muons. Inc., USA M.A. Leonova, A. Moretti, M. Popovic, A.V. Tollestrup, K. Yonehara Fermilab, Batavia, USA Y. Torun IIT, Chicago, Illinois, USA
	It is important to make a compact muon ionization cooling channel to increase the cooling efficiency (muon survival rate, cooling decrement, etc). A proposed scheme to reduce the radial size of RF cavities at a given resonance frequency is to insert a dielectric material into the RF cavity. In vacuum cavities, however, dielectric materials are extremely susceptible to breakdown in high power conditions. High-pressure hydrogen gas has been shown to inhibit breakdown events in RF cavities in strong magnetic fields. An experiment has been designed to test surface breakdown of alumina in RF cavities. A structure has been designed to maximize the parallel field parallel to the surface while bringing the cavity into a desired frequency range (800-810MHz). Alumina is tested in this configuration under high power conditions. The experimental result will be shown in this presentation.

TUPFI081	Progress with Coherent Electron Cooling Proof-Of-Principle Experiment	electron, gun, ion, undulator	1535
	I. Pinayev, S.A. Belomestnykh, I. Ben-Zvi, K.A. Brown, J.C. Brutus, L. DeSanto, A. Elizarov, C. Folz, D.M. Gassner, Y. Hao, R.L. Hulsart, Y.C. Jing, D. Kayran, R.F. Lambiase, V. Litvinenko, G.J. Mahler, M. Mapes, W. Meng, R.J. Michnoff, T.A. Miller, M.G. Minty, P. Orfin, A. Pendzick, F. Randazzo, T. Rao, T. Roser, J. Sandberg, B. Sheehy, J. Skaritka, K.S. Smith, L. Snydstrup, R. Than, R.J. Todd, J.E. Tuozzolo, G. Wang, D. Weiss, M. Wilinski, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA G.I. Bell, J.R. Cary, K. Paul, B.T. Schwartz, S.D. Webb Tech-X, Boulder, Colorado, USA C.H. Boulware, T.L. Grimm, R. Jecks, N. Miller Niowave, Inc., Lansing, Michigan, USA M.A. Kholopov, P. Vobly BINP SB RAS, Novosibirsk, Russia M. Poelker JLAB, Newport News, Virginia, USA
	We conduct proof-of-the-principle experiment of coherent electron cooling (CEC), which has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. In this paper, we present the progress with experimental equipment including the first tests of the electron gun and the magnetic measurements of the wiggler prototype. We describe current design status as well as near future plans.

TUPFI087	Alternative Muon Cooling Options based on Particle-Matter-Interaction for a Neutrino Factory	lattice, focusing, solenoid, proton	1550
	D. Stratakis BNL, Upton, Long Island, New York, USA A. Alekou CERN, Geneva, Switzerland D.V. Neuffer, P. Snopok Fermilab, Batavia, USA J. Pasternak STFC/RAL, Chilton, Didcot, Oxon, United Kingdom 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 P. Snopok Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: This work is funded by US Dept. of Energy grant numbers DE AC02-98CH10886 An ionization cooling channel is a tightly spaced lattice containing absorbers for reducing the momentum of the muon beam, rf cavities for restoring the momentum and strong solenoids for focusing the beam. Such a lattice is an essential feature of most designs for Neutrino Factories and Muon Colliders. Here, we explore three different approaches for designing ionization cooling channels with periodic solenoidal focusing. Key parameters such as the engineering constraints that are arising from the length and separation between the solenoidal coils are systematically examined. In addition, we propose novel approaches for reducing the peak magnetic field inside the rf cavities by using either a magnetic shield system or a bucked coils configuration. Our lattice designs are numerically examined against two independent codes: The ICOOL and G4BL code. The feasibility of our proposed cooling channels to muon accelerators is examined by applying the proposed lattices to the front-end of a Neutrino Factory.

TUPME015	Proposal of Polarized Gamma-ray Source for ILC Based on CSR Inverse Compton Scattering	electron, positron, scattering, laser	1598
	M. Shimada, K. Yokoya KEK, Ibaraki, Japan R. Hajima JAEA, Ibaraki-ken, Japan M. Tecimer University of Hawaii at Manoa, Honolulu, USA
	The positron source of International Linear Collider (ILC) requires a circular polarized gamma-ray with a flux more than 10¹⁶ phs./s and a helical undulator-based gamma-ray source is proposed in the baseline design. Although the undulator scheme is technically feasible, it is not easy for a stand-alone operation because of the required electron energy, ~ 150GeV. In this paper, we propose an alternative method, the inverse Compton scattering with a high-power mid-infrared optical pulse generated from coherent synchrotron radiation (CSR). To achieve the high flux gamma-ray, CSR with a few MHz is stacked in a high-finesse optical cavity made of a photonic crystal. In the proposed scheme, a stand-alone operation is feasible because the electron energy is less than 10GeV.

TUPME026	Optimization on RF parameters of a Choke-Mode Structure for the Clic Main LINAC	wakefield, simulation, linac, accelerating-gradient	1628
	H. Zha, H.B. Chen, J. Shi TUB, Beijing, People's Republic of China
	Funding: This work was support by the National Natural Science Foundation of China (Grant No. 11135004). A tapered choke-mode structure for the main linac of Compact Linear Collider (CLIC) had been designed. Wakefield suppression of this structure fits the beam dynamic requirements. But it has a lower RF performance compared to the baseline design of CLIC main linac. A genetic algorithm is used in the procedure to find the optimum solution. A new choke-mode structure with 24 regular cells working on 100MV/m has been design, which fits beam dynamic constraints and has higher RF efficiency and lower surface field.

TUPME065	Experimental Study of Horizontal-Longitudinal Coupling at CesrTA	coupling, lattice, simulation, scattering	1715
	M. P. Ehrlichman, A. Chatterjee, W. Hartung, D.P. Peterson, N.T. Rider, D. L. Rubin, J.P. Shanks, S. Wang CLASSE, Ithaca, New York, USA
	Funding: This research was supported by NSF and DOE contracts PHY-0734867, PHY-1002467, PHYS-1068662, DE-FC02-08ER41538, DE-SC0006505. In storage rings, the presence of horizontal dispersion in the RF cavities introduces x-z coupling. The result is that the beam is skewed in the horizontal-longitudinal plane. The skew angle is proportional to the V15 term of the 6X6 coupling matrix which is proportional to the RF cavity voltage and the horizontal dispersion in the cavity. Here we report experiments at CesrTA where x-z coupling was explored using three distinct lattice configurations with different V15 coupling terms. We explore x-z coupling for each of these lattices by measuring the horizontal projection of the beam with a beam size monitor, as the RF voltage is varied. The first lattice has about 1 m dispersion in the RF cavities, resulting in a V15 term at the beam size monitor source point corresponding to 16 mrad x-z tilt. In the second, the V15 generated in one pair of cavities is compensated at the second pair by adjusting the horizontal betatron phase advance between the cavity pairs. In the third, the optics are adjusted so that the RF cavity region is dispersion-free, eliminating the coupling entirely. Additionally, intra-beam scattering is evident in our measurements of beam size vs. RF voltage.

TUPWA018	Local Compensation-Rematch for Element Failures in the Low Energy Section of C-Ads Accelerator	solenoid, emittance, linac, focusing	1760
	B. Sun, Z. Li, J.Y. Tang, F. Yan IHEP, Beijing, People's Republic of China
	Due to the requirement of high reliability and availability for the C-ADS accelerators, a fault tolerance design is pursued. The effects of transverse focusing element failures in different locations have been studied and the schemes of compensation by means of local compensation have been investigated. After one transverse element failure especially in the low energy section happens, some new methods have been purposed by which the new settings of the neighbouring solenoids and the cavities can be set, and the Twiss parameters and energy can be approximately recovered to that of the nominal ones at the matching point. We find that the normalized RMS emittance in transverse and longitudinal planes have no obvious growth after applying the compensation in each section of the main linac. When we make study on the compensation-rematch for the RF cavity failures, the TraceWin code has been used that doesn’t consider the phase change during the cavity resetting, so a code named LOCCOM, which is based on MATLAB, is developed and used to compensate the error on arrival-time at the matching point.

TUPWA021	Multi-Pass, Multi-Bunch Beam Breakup of ERLs with 9-cell Tesla Cavities	HOM, betatron, dipole, simulation	1769
	S. Chen, J.E. Chen, L.W. Feng, S. Huang, Y.M. Li, K.X. Liu, S.W. Quan, F. Zhu PKU, Beijing, People's Republic of China
	Funding: Supported by the Major State Basic Research Development Program of China under Grant No. 2011CB808303 and No. 2011CB808304 In this paper, multi-pass, multi-bunch beam break-up of some small-scale Energy Recovery Linac(ERL) configuration using 9-cell Tesla cavity is discussed. The threshold currents of different cases are investigated and some factors that influence the threshold currents are discussed.

TUPWA022	Beam Dynamics Design of a 325 MHz RFQ	rfq, emittance, proton, simulation	1772
	F.J. Jia, J.E. Chen, G. Liu, Y.R. Lu, X.Q. Yan PKU, Beijing, People's Republic of China B.Q. Cui, J.H. Li, G.H. Wei CIAE, Beijing, People's Republic of China
	The beam dynamic design of a 325 MHz Radio Frequency Quadrupole (RFQ) is presented in this paper. This 4-vane RFQ will accelerate pulsed proton beam from 30 keV to 3 MeV with repetition frequency of 1 MHz. A 1 MHz chopper and a 5 MHz buncher are arranged in the Low-Energy-Beam-Transport (LEBT) to produce the injected beam. The beam length at the RFQ entrance is about 3 ns, and the energy-spread is about 10%. The code of PARMTEQM is used to simulate RFQ structure. The design should realize high transmission for very high intensity beam meanwhile low emittance growth and relatively short length should be kept.

TUPWA023	Design of the Tuning System for the He⁺ Coupled RFQ-SFRFQ Cavity	rfq, simulation, linac, impedance	1775
	W.L. Xia, J.E. Chen, S.L. Gao, Z.Y. Guo, Y.R. Lu, S.X. Peng, Z. Wang, X.Q. Yan, J. Zhao, K. Zhu PKU, Beijing, People's Republic of China
	Funding: Supported by NSFC 10905003, 11079001, 91026012 Corresponding author: wangzhi@pku.edu.cn The CRS (coupled RFQ-SFRFQ) cavity is a new type linac that couples traditional RFQ (radio frequency quadrupole) and SFRFQ (separated function RFQ) electrodes into a single cavity. The overall design of the CRS cavity has been completed and the linac is being manufactured currently. In this paper, we aimed to design a frequency tuning system for the CRS cavity, which will be used to explore the electromagnetic field distribution between RFQ and SFRFQ sections in the cavity. The frequency range, variation of Q value, power consumption and electric field distribution were investigated. Based on the beam dynamic program SFRFQDYNv1.0, we analysed the beam transmission properties of the cavity under the unbalanced electric field distribution. The optimized parameters of the tuning system were obtained.

TUPWA038	Equilibrium Bunch Density Distribution with Passive Harmonic Cavities in the MAX IV 3 GeV Storage Ring	impedance, storage-ring, emittance, damping	1790
	P.F. Tavares, Å. Andersson, A. Hansson MAX-lab, Lund, Sweden
	The MAX IV storage rings will use third harmonic cavities operated passively to lengthen the bunches and alleviate collective instabilities. These cavities are an essential ingredient in the MAX IV design concept and are required for achieving the final design goals in terms of stored current, beam emittance and beam lifetime. This paper reports on fully self-consistent calculations of the longitudinal bunch density distribution in the MAX IV 3 GeV storage ring, which indicate that up to a factor 5 increase in RMS bunch length is achievable with a purely passive system.

TUPWA044	Longitudinal Coupled-Bunch Oscillation Studies in the CERN PS	damping, feedback, kicker, emittance	1808
	H. Damerau, S. Hancock, M.M. Paoluzzi CERN, Geneva, Switzerland M. Migliorati, L. Ventura Rome University La Sapienza, Roma, Italy
	Longitudinal coupled-bunch oscillations are an important limitation for the high-brightness beams accelerated in the CERN PS. Up to the present intensities they are suppressed by a dedicated feedback system limited to the two dominant oscillation modes. In view of the proposed installation of a wide-band feedback kicker cavity within the framework of the LHC Injectors Upgrade project (LIU), measurements have been performed with the existing damping system with the aim of dimensioning the new one. Following the excitation of well-defined oscillation modes, damping times and corresponding longitudinal kick strength are analysed. The paper summarizes the results of the observations and gives an outlook on the expected performance with the new coupled-bunch feedback.

TUPWO005	Survey of Beam Optics Solutions for the MLS Lattice	optics, emittance, quadrupole, lattice	1883
	M. Ries, J. Feikes, T. Goetsch, G. Wüstefeld HZB, Berlin, Germany
	The Metrology Light Source (MLS) is an electron storage ring containing 24 quadrupole magnets which can be powered individually. Fully exploring the capabilities of the machine optics by tracking or experiment would be very time consuming. Therefore the quadrupoles were combined in five families and a numerical brute force approach was used to scan for areas of stable solutions in the scope of linear beam optics. In order to get information on the expected beam lifetimes for each generated optics, a model for the Touschek lifetime was implemented. Simulation results as well as experimental tests of selected optics will be presented.

TUPWO016	Beam Dynamics Design of 3 MeV Medium Energy Beam Transport for Beam Intensity Upgrade of J-PARC Linac	emittance, DTL, simulation, linac	1916
	T. Maruta KEK/JAEA, Ibaraki-Ken, Japan M. Ikegami J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	The J-PARC linac has a plan to upgrade its beam power in the summer 2013. This plan includes the replacement of the front-end components (ion source and 3 MeV RFQ) to increase the peak current from present 30 mA to 50 mA. Since it results in the different injection beam profile to medium energy beam transport (MEBT), which locates the RFQ downstream, we designed the beam dynamics of MEBT. In this presentation, we disscuss the new design of beam dynamics in MEBT.

TUPWO019	A Local Achromatic Design of C-ADS MEBT2	emittance, linac, bunching, controls	1922
	H. Geng, Z. Guo, Z. Li, C. Meng, S. Pei, J.Y. Tang IHEP, Beijing, People's Republic of China
	The accelerator of China Accelerator Driven Sub-critical system consists of two injectors to ensure its high reliability. The Medium Energy Beam Transport line-2 is an essential part of the accelerator to transport and match the beam from either injector to the main linac. This paper presents a local achromatic design, which uses four bending magnets, for CADS MEBT2. It is found that both transverse and longitudinal emittance growths can be well controlled below 15% from MEBT2 entrance to the exit of the following superconducting spoke-021 section. The beam dynamics of MEBT2 will be discussed and the multi-particle tracking results will also be shown.

TUPWO020	Error Analysis for C-ADS MEBT2	emittance, linac, beam-transport, solenoid	1925
	H. Geng, Z. Guo, Z. Li, C. Meng, S. Pei, J.Y. Tang IHEP, Beijing, People's Republic of China
	A local achromatic scheme has been developed for C-ADS MEBT2. This paper presents the error analysis results for this MEBT2 scheme. The effects of magnet and cavity misalignment, static and dynamic errors of electric and magnetic field, the displacement of the input beam as well as the initial mismatches of the incoming beam will be studied. Beam trajectory correction scheme will also be discussed.

TUPWO029	Beam Line Design at the CAEP THz Free Electron Laser	electron, emittance, laser, FEL	1937
	P. Li, W. Bai, H. Wang CAEP/IAE, Mianyang, Sichuan, People's Republic of China X. Li TUB, Beijing, People's Republic of China
	China Academy of Physics (CAEP) is currently building a THz Free Electron Laser (THz-FEL) which serves as a radiation light sourse used for research in a variety of experimental fields. In this paper, we present the design of the beam line, which was accomplished using PARMELA and TRANSPORT code simulations. The accelerator consists of a 350 kV photocathode DC gun in conjunction with one cryomodule containing two 4-cell superconductiong RF cavities. The energy of the elctron beam is 7~8 MeV, and the maximum of the average beam current is 5 mA. A transverse emittance typically below 10 pi mm.mrad can be achieved.

TUPWO046	The ESS Linac Simulator: A First Benchmark with TraceWin	space-charge, linac, simulation, multipole	1970
	E. Laface, M. Eshraqi, R. Miyamoto ESS, Lund, Sweden
	The ESS Linac Simulator, ELS, will be the core of the online model used in the normal operations of the ESS linac. ESS Linac Simulator will operate through the eXtensible Accelerator Language, XAL, in order to provide an effective interface capable to simulate and predict the beam dynamics of the accelerator. The ELS is capable of simulating the dynamics of the beam envelope in both transverse and longitudinal planes in real time. In order to validate the effectiveness of the physics implemented, the ELS calculations are here benchmarked with TraceWin: the simulation code used for the design of the accelerator.

WEOAB101	Single Particle Tracking for Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring	HOM, simulation, synchrotron, optics	2038
	M. Ruprecht, A. Jankowiak, A. Neumann, M. Ries, G. Wüstefeld HZB, Berlin, Germany T. Weis DELTA, Dortmund, Germany
	A scheme where 1.5 ps and 15 ps long bunches (rms) can be stored simultaneously in the BESSY II storage ring has recently been proposed (BESSY^VSR). This paper presents simulations of single particle beam dynamics influenced by superconducting cavities used for the strong longitudinal beam focusing. The effect of RF jitter on (very short) bunches is investigated and results are discussed. Furthermore, possible effects on beam dynamics during ramp up and ramp down of the high gradient fields in the cavities are studied. The primary goal is to reveal preliminary design specifications for RF jitter on the basis of single particle dynamics. G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries, Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring, Proceedings of IPAC2011, San Sebastián, Spain
	Slides WEOAB101 [3.955 MB]

WEYB101	Power Upgrade of J-PARC Linac	rfq, ion, linac, ion-source	2047
	H. Oguri JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	A linac power upgrade program is now in progress after a successful recovery from the earthquake disaster. The power upgrade includes an ion source, an RFQ and a 400 MeV Annular-ring Coupled Structure (ACS) linac. We started a full-scale development of a cesium seeded RF-driven negative hydrogen ion source. The ion source extracted the beam of more than 60 mA with a duty factor of 2.5 %, which is satisfied with the requirement of the program. A new RFQ for 50 mA acceleration is under construction on the basis of a RFQ fabrication process, which was built as a backup for the present RFQ. Mass production of the ACS modules have almost completed. There is a plan to install these components and schedule the beam test in 2013. This presentation will cover the power upgrade status of the J-PARC linac.
	Slides WEYB101 [4.205 MB]

WEIB202	Industrialization of the ILC Project	SRF, linac, linear-collider, collider	2105
	M.C. Ross SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515. The International Linear Collider Global Design Effort (GDE) team completed the Technical Design Report (TDR) in early 2013. The TDR consists of a description of the machine design, a summary of the R&D program carried out in support of the design, a cost estimate and a project plan. The number of high technology components to be fabricated for ILC is large, similar to that built for the Large Hadron Collider, and industrial partners have had an important role throughout the technical development and design period. It is recognized that transfer of new technology to industrial partners and subsequent collaborative development can be difficult. To counter this, the ILC Technical Design Phase (TDP) team arranged a series of vendor visits, component development contracts, workshop satellite meetings and industrial production study contracts. The GDE collaboration provided the framework for development through an agreed-upon performance parameter set and project implementation scheme. The latter includes a ‘plug-compatibility’ policy that promotes innovation as long as specified interface conditions are met. In this paper we show the evolution of the technology from the labs where it was developed to the companies where high performance cavities are now routinely produced. The longest journey: the LHC dipoles arrive on time. http://cerncourier.com/cws/article/cern/29723 ** Office of High Energy Physics Accelerator R&D Task Force Report http://www.acceleratorsamerica.org/report/accelerator_task_force_report.pdf
	Slides WEIB202 [5.181 MB]

WEIB203	Industrialization of ILC from a View Point of Industry	HOM, target, vacuum, status	2110
	K. Sennyu, H. Hara, F. Inoue, K. Kanaoka, K. Okihira MHI, Hiroshima, Japan
	Cavity performance has been improved by various efforts to meet the ILC spec stably in these days. For industrialization, not only Quality but also Cost and Delivery time, that is, QCD are important. We report our activities for stable quality and cost reduction in this report.
	Slides WEIB203 [5.789 MB]

WEPWA009	RF Bunch Compression Studies for FLUTE	linac, simulation, gun, space-charge	2144
	M. Schuh, E. Huttel, S. Marsching, A.-S. Müller, S. Naknaimueang, M.J. Nasse, R. Rossmanith, R. Ruprecht, M. Schreck, M. Schwarz, M. Weber, P. Wesolowski KIT, Karlsruhe, Germany R.W. Aßmann, K. Flöttmann, H. Schlarb DESY, Hamburg, Germany
	FLUTE is a planned 40 to 50 MeV accelerator test facility consisting, in the first phase, of an electron gun with an output energy of about 7 MeV, a traveling wave linac and a magnet chicane bunch compressor. The machine will serve as a source of intense THz radiation using coherent synchrotron radiation (CSR), coherent transition radiation (CTR), and coherent edge radiation (CER) as generation mechanisms. It is planned to operate the machine in the charge regime from a few pC up to several nC in order to study bunch compression schemes as well as the THz radiation generation. In this contribution the effect of velocity bunching by using a dedicated buncher cavity at low energy and operating the linac off-crest is studied in order to deliver RMS bunch lengths in the femtosecond range at low charge.

WEPWA017	Development of Laser-Compton X-ray Source using Optical Storage Cavity	laser, electron, booster, linac	2165
	K. Sakaue, M. Washio Waseda University, Tokyo, Japan M.K. Fukuda, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	Funding: Work supported by the Quantum Beam Technology Program of MEXT and JSPS Grant-in-Aid for Young Scientists (B) 23740203 We have been developing a pulsed-laser storage technique in a super-cavity for a compact x-ray sources. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. We already obtained a pulse-train x-rays through the laser-Compton scattering between a multi-bunch electron beam and an optical super-cavity. And also, we performed a X-ray imaging via laser-Compton X-ray. On these successful results, we decided to upgrade our system for increasing X-ray flux by 3-order of magnitudes for practical use. For an optical cavity, we designed 4-mirrors bow-tie cavity in order to increase the power. On the other hand, electron accelerator was also upgraded to increase the bunch number in the train. We use 3.6cells rf-gun and 12cell standing wave booster linac. As a result, 2-order increase of X-ray flux was achieved. Design of upgraded our laser-Compton X-ray source, the results of X-ray experiments and future prospective will be presented at the conference.

WEPWA020	Laser Electron Storage Ring for TTX	laser, electron, storage-ring, quadrupole	2171
	H.S. Xu, W.-H. Huang, C.-X. Tang, L.X. Yan, Y. You TUB, Beijing, People's Republic of China D. Jehanno, Z.F. Zomer LAL, Orsay, France S.-Y. Lee IUCEEM, Bloomington, Indiana, USA
	Tsinghua Thomson scattering X-ray (TTX) source, proposed by Tsinghua University, is a hard x-ray source with multi-application in condensed matter physics, etc. The TTX is composed of an S-band photocathode RF gun and a SLAC type 3m travelling wave Linac, and a femto-second tera-watt laser system drives the photocathode. The TTX source is in operation. To extend the capability of TTX, we plan to design a ring based system to increase the photon flux. In this paper, we report the design of the compact electron storage ring and optical cavity, expected performance, and future prospects.

WEPWA037	Effect of Ground Vibration on the Out-coupled Power in a Terahertz FEL Oscillator	FEL, simulation, alignment, laser	2211
	Q. Fu, L.Z. Deng, B. Qin, P. Tan, Y.Q. Xiong, Y.B. Yibin, H. Zeng HUST, Wuhan, People's Republic of China
	To acquire high power out-coupled, we must ensure the co-axis of electron orbit, optical beam and magnetic field. The propagation of ground vibration through the optical platform will lead to misalignment of the optical axis in the FEL optical cavity. Based on measurement results of the ground vibration, simulations of misalignment are studied with GENESIS+OPC. The tolerance of mirror tilt and offset is also discussed.

WEPWA047	Longitudinal Stability of Multiturn ERL with Split Accelerating Structure	linac, electron, simulation, resonance	2226
	Ya.V. Getmanov, O.A. Shevchenko, N. Vinokurov BINP SB RAS, Novosibirsk, Russia T. Atkinson HZB, Berlin, Germany N. Vinokurov KAERI, Daejon, Republic of Korea
	Some modern projects of the new generation light sources use the conception of multipass energy recovery linac with split (CEBAF-like) accelerating structures. One of the advantages of these light sources is the possibility to obtain a small longitudinal beam size. To help reduce it, the longitudinal dispersion should be non-zero in some arcs of the accelerator. However small deviations in voltages of the accelerating structures can be enhanced by induced fields from circulating bunches due to the dependence of the flight time on the energy spread and the high quality factor of the superconducting radio-frequency cavities. Therefore, instabilities related with interactions of the electron bunches and longitudinal modes of the cavities can develop in the installation. Stability conditions for the interactions with fundamental accelerating mode of the split accelerating system are discussed. Numerical simulations are made for two projects - MARS and FSF.

WEPWA058	Operation of the NSRRC 2998 MHz Photo-cathode RF Gun	gun, laser, electron, cathode	2247
	A.P. Lee, M.C. Chou, J.-Y. Hwang, W.K. Lau NSRRC, Hsinchu, Taiwan P. Chiu, N.Y. Huang, P. Wang NTHU, Hsinchu, Taiwan
	We are developing the photoinjector technology for single pass high gain FEL research at NSRRC. A gun test facility(GTF) equipped with a 35 MW, S-band high power pulsed klystron as well as a 300 uJ, UV driver laser has been constructed for testing photo-cathode rf guns. Recently, a 2998 MHz, 1.6-cell photo-cathode rf gun has been fabricated in house and is being tested at the NSRRC GTF. Details of this setup will be described and the operational performance of this electron gun will be reported.

WEPWA068	Design Concepts for the NGLS Linac	linac, cryomodule, cryogenics, HOM	2271
	A. Ratti, J.M. Byrd, J.N. Corlett, L.R. Doolittle, P. Emma, J. Qiang, M. Venturini, R.P. Wells LBNL, Berkeley, California, USA C. Adolphsen, C.D. Nantista SLAC, Menlo Park, California, USA D. Arenius, S.V. Benson, D. Douglas, A. Hutton, G. Neil, W. Oren, G.P. Williams JLAB, Newport News, Virginia, USA C.M. Ginsburg, R.D. Kephart, T.J. Peterson, A.I. Sukhanov Fermilab, Batavia, USA
	The Next Generation Light Source (NGLS) is a design concept for a multibeamline soft x-ray FEL array powered by a ~2.4 GeV CW superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. This paper describes the concepts under development for a linac operating at 1.3 GHZ and based on minimal modifications to the design of ILC cryomodules in order to leverage the extensive R&D that resulted in the ILC design. Due to the different nature of the two applications, particular attention is given here to high loaded Q operation andμphonics control, as well as high reliability and expected up time.

WEPWA069	Design Concepts for an RF Deflecting Cavity-Based Beam Spreader for a Next Generation FEL	dipole, FEL, gun, septum	2274
	M. Placidi, L.R. Doolittle, P. Emma, J.-Y. Jung, J. Qiang, A. Ratti, C. Sun LBNL, Berkeley, California, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 The Lawrence Berkeley National Laboratory (LBNL) is developing design concepts for a multi-beamline soft x-ray FEL array powered by a superconducting linear accelerator, operating with a high bunch repetition rate of approximately one MHz. Electron bunches supplied by a high-brightness, high-repetition-rate photocathode electron gun are distributed by a beam spreader, designed to deliver individual bunches from a CW linac to an array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. We describe recent developments in the technical choices, design and parameters of the spreader system and its main components.

WEPWA078	Compact Accelerator Design for a Compton Light Source	electron, gun, emittance, photon	2292
	T. Satogata, K.E. Deitrick, J.R. Delayen, B.R.P. Gamage, K.G. Hernández-Chahín, C.S. Hopper, G.A. Krafft, R.G. Olave ODU, Norfolk, Virginia, USA K.G. Hernández-Chahín DCI-UG, León, Mexico G.A. Krafft, T. Satogata JLAB, Newport News, Virginia, USA
	Funding: Partially authored by Jefferson Science Associates, LLC under U.S. DOE contract NO. DE-AC05-06OR23177. A compact electron accelerator suitable for Compton source applications is in design at the Center for Accelerator Science at Old Dominion University and Jefferson Lab. The design includes a KE=1.55 MeV low-emittance, optimized superconducting electron gun; a 23.45 MeV linac with multi-spoke 4.2 K superconducting cavities; and transport that combines magnetic longitudinal bunch compressor and transverse final focus. We report on the initial designs of each element, including end to end simulations with ASTRA and elegant, and expected beam parameters.

WEPWO002	RF Measurements of the 1.6 Cell Lead/Niobium Photoinjector in HoBiCaT	gun, cathode, vacuum, SRF	2313
	A. Burrill, W. Anders, T. Kamps, J. Knobloch, O. Kugeler, P. Lauinger, A. Neumann HZB, Berlin, Germany P. Kneisel JLAB, Newport News, Virginia, USA R. Nietubyć NCBJ, Świerk/Otwock, Poland J.K. Sekutowicz DESY, Hamburg, Germany
	The development of a simple and robust SRF photoinjector capable of delivering up to 1 mA average current in c.w. operation continues to progress with the horizontal RF testing of the 1.6 cell Pb/Nb hybrid photoinjector. This injector utilizes a sputtered lead coating on a removable Nb cathode plug as the photoelectron source and has recently been tested in the horizontal test cryostat facility, HoBiCaT, at HZB. In this paper we will report on the status of these RF measurements and compare the performance to previous vertical RF tests performed at JLab. We will also report on the experience operating this cavity with a TTF-III high power RF input coupler, as well as provide a summary of the microphonics susceptibility now that it has been installed into a helium vessel and equipped with a Saclay style tuner.

WEPWO004	Studies of Systematic Flux Expulsion in Superconducting Niobium	niobium, simulation, lattice, controls	2316
	J.M. Vogt, J. Knobloch, O. Kugeler HZB, Berlin, Germany
	The quality factor Q0 that can be obtained in a superconducting cavity is known to depend on various factors like niobium material properties, treatment history and magnetic shielding. We believe that cooling conditions have an additional impact, as they appear to influence the amount of trapped flux and hence the residual resistance. We have constructed a test stand using niobium rods to study flux trapping. Here we can precisely control the temperature and approach Tc from below in the superconducting state. Although the sample remains in the superconducting state, a change in the amount of trapped flux is visible. The procedure can be applied repeatedly resulting in a significantly lowered level of trapped flux in the sample. Furthermore, simulations using the Radia software package for Mathematica developed by the ESR were used to better unterstand the measured changes in magnetic flux around the Sample. Applying a similar procedure for minimization of trapped magnetic flux to a superconducting cavity could allow for reduction of the magnetic contribution to the surface resistance and result in a significant improvement of Q0.

WEPWO005	Microphonics Analysis of the SC 325 MHz CH-Cavity	simulation, resonance, vacuum, status	2319
	M. Amberg, M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany M. Amberg, K. Aulenbacher HIM, Mainz, Germany K. Aulenbacher IKP, Mainz, Germany
	Since the walls of superconducting (sc) cavities are kept very thin to support the cooling process, even small mechanical disturbances can detune the cavity. One of the main sources of detuning a cavity is microphonics. These low-frequent vibrations caused by vacuum pumps or underground noise are transferred to the cryostat and excite mechanical resonances of the cavity which may lead to frequency shifts larger than the bandwidth. To determine the mechanical resonance frequencies of the sc 325 MHz CH-cavity (Crossbar-H-Mode) simulations with ANSYS Workbench have been performed in a first step. Additionally, microphonics measurements were taken at room temperature as well as in a vertical cryostat at 4K in the cryo-lab of the IAP, Frankfurt University. Furthermore, the contraction of the cavity walls and the resulting frequency shift due to the cavity cool-down has been measured. A comparison between simulation results and the measured values is presented in this paper.

WEPWO007	Shape Optimization of a SRF Injector Cavity	emittance, solenoid, cathode, electron	2322
	J.K. Sekutowicz DESY, Hamburg, Germany W.C. Grabowski, R. Nietubyć, T. Wasiewicz NCBJ, Świerk/Otwock, Poland
	In this contribution we present studies on the shape optimization of 1.6-cell cavity with solenoid for a 1-mA class photo injector, meant as an electron source for FEL facilities. The main criterion for the optimization was the lowest slice emittance. Inclination angle of the cavity back wall, solenoid position and magnetic field, amplitude of the accelerating field, and emission phase were varied in these studies in order to find the minimum of slice emittance at the distance of 1 m from a photocathode, located in center of the cavity back wall

WEPWO008	SRF Conical Half-wave Resonator Tuning Developments	simulation, target, resonance, cryomodule	2325
	E.N. Zaplatin FZJ, Jülich, Germany A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA
	Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302. A conical Half-Wave Resonator is considered as an option for a first accelerating cavity for β=v/c=0.11 with the resonance frequency 162.5 MHz for a high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory (Project X). We present results of different options of the cavity mechanical tuning. The "standard" tuning method of beam port deformations is an effective tuning method still requiring a relatively high tuning pressure. The side tuning is considered as a novel option for the resonance frequency adjustment featuring lower tuning force and an option of the structure design for the resonator frequency shift self compensation.

WEPWO009	Numerical Coupling Analyses of BERLinPro SRF Gun	gun, simulation, SRF, cathode	2328
	E.N. Zaplatin FZJ, Jülich, Germany W. Anders, A. Burrill, T. Kamps, J. Knobloch, O. Kugeler, A. Neumann HZB, Berlin, Germany
	BERLinPro is an approved ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity (1300 MHz, β=1) for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.8 MeV kinetic energy while limited by fundamental power coupler performance to about 230 kW forward power. The RF and beam dynamics gun cavity features 1.4 λ/2 cell resonator. We present results of mechanical structure developments of SRF gun. The main purpose of the whole structure optimization was the design of the gun helium vessel together with the tuner and stiffening rings to provide the simple construction for structure tuning with minimization of the cavity frequency dependence on external pressure. During the resonator tuning and external load structure deformations the cavity field profile variation along the beam path should stay within 5%.

WEPWO010	BERLinPro Seven-cell SRF Cavity Optimization and HOMs External Quality Factors Estimation	HOM, factory, SRF, simulation	2331
	T. Galek, K. Brackebusch, T. Flisgen, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany J. Knobloch, A. Neumann HZB, Berlin, Germany B. Riemann, T. Weis DELTA, Dortmund, Germany
	Funding: Work funded by EU FP7 Research Infrastructure Grant No. 227579 and by German Federal Ministry of Research and Education, Project: 05K10HRC. The main scope of this work is the optimization of the superconducting radio frequency (SRF) accelerating cavity design for the Berlin Energy Recovery Linac Project (BERLinPro). BERLinPro shall serve as a demonstrator for 100-mA-class ERLs with CW LINAC technology. High-current operation requires an effective damping of higher-order modes (HOMs) of the 1.3 GHz main-linac cavities. Consequently it is important, at the SRF cavity design optimization stage, to calculate the external quality factors of HOMs to avoid beam break up (BBU) instabilities. The optimization of the SRF cavity design consists of two steps. In the first step the cavities' end half-cells are tuned with respect to field flatness, effective shunt impedance and geometrical factor of the fundamental accelerating mode using robust eigenmode simulations. The second step involves frequency domain simulations and the extraction of external quality factors of HOMs from transmission S-parameter spectra using vector fitting procedure and an automated scheme to remove non-static poles . The eigenmode,as well as the frequency domain simulations are performed using CST Microwave Studio *. A. Neumann et al., Proc. of ICAP2012, pp. 278–280. T. Galek et al., Proc. of ICAP2012, pp. 152–154. * CST AG, http://www.cst.com

WEPWO011	In-vacuum Temperature Measurement of Niobium Components using Infrared Pyrometry during Electron Beam Welding Procedure	vacuum, electron, controls, shielding	2334
	L. Monaco, P. Michelato, C. Pagani, D. Sertore INFN/LASA, Segrate (MI), Italy V. Battista, G. Corniani, M. Festa Ettore Zanon S.p.A., Schio, Italy
	Electron beam welding (EBW) is widely used in the construction of Niobium Superconducting RF cavities. The welding sequence of such a complex structure, foresees many welding operations. The welding parameters depend on many variables as the material thickness, but also on the component temperature before each weld. This paper presents a technique to measure the temperature of Nb components in vacuum during the EBW operation using an IR pyrometer placed outside the vacuum chamber through an appropriate vacuum viewport. With the current configuration the system can measure temperatures up to 350°C in the vacuum conditions of the EBW vacuum chamber (10-5-10^-6 mbar). The technique was used to optimize the time interval between each subsequent equatorial weld operation during Nb cavities production at Ettore Zanon, increasing the welding procedure reliability and decreasing the waiting time by control of the temperatures in the weld region. Moreover this technique can be generally used for in vacuum measurements of components from room temperature up to about 350 °C. Future developments are under way to make this technique compatible with UHV and increasing the measurement range.

WEPWO012	XFEL 3.9 GHz Prototype Cavities Tests	HOM, pick-up, status, diagnostics	2337
	P. Pierini, M. Bertucci, A. Bosotti, C. Maiano, P. Michelato, L. Monaco, R. Paparella, D. Sertore INFN/LASA, Segrate (MI), Italy E.R. Harms Fermilab, Batavia, USA C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy E. Vogel DESY, Hamburg, Germany
	In preparation for the XFEL components production, three prototype cavities have been manufactured and vertically tested at INFN-LASA. Several tests, with and without HOM antennas and in a double cavity test configuration, have been performed. Further tests of one of the prototypes took place at FNAL, to validate results between the two test facilities. Results were consistent with those obtained at INFN-LASA.

WEPWO013	High Power Tests of Injector Cryomodule for Compact-ERL	cryomodule, HOM, radiation, accelerating-gradient	2340
	E. Kako, D.A. Arakawa, K. Hara, T. Honma, H. Katagiri, Y. Kojima, Y. Kondo, S. Michizono, T. Miura, H. Nakai, H. Nakajima, K. Nakanishi, S. Noguchi, T. Shishido, T. Takenaka, K. Watanabe, Y. Yamamoto KEK, Ibaraki, Japan H. Hara, H. Hitomi, K. Sennyu MHI, Kobe, Japan
	In the cERL injector cryomodule, electron beams of 10 mA are accelerated from the beam energy of 500 keV to 5 MeV. A three 2-cell cavity system was chosen for the cERL injector. Each cavity is driven by two input couplers to reduce a required RF power handling capacity and also to compensate a coupler kick. In the cERL injector cryomodule, critical hardware components are not superconducting cavities but RF input couplers operating in CW mode. Six input couplers for the installation in the cryomodule were fabricated, and three pairs of input couplers were carefully conditioned. Costruction status, cool-down tests and high power RF test results on injector cryomodule for compact-ERL at KEK will be discussed in this paper.

WEPWO014	Rf Field-Attenuation Formulae for the Multilayer Coating Model	vacuum, coupling, electromagnetic-fields	2343
	T. Kubo, T. Saeki KEK, Ibaraki, Japan Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan
	Formulae that describe the RF electromagnetic field attenuation in the multilayer coating model with a single superconductor layer and a single insulator layer deposited on a bulk superconductor are derived with a rigorous calculation based on the Maxwell equations and the London equation.

WEPWO015	Electron Beam Welding for High Gradient Superconducting Cavity	electron, superconducting-cavity, linear-collider, collider	2346
	T. Kubo, Y. Ajima, H. Hayano, H. Inoue, S. Kato, T. Saeki, M. Sawabe, K. Umemori, Y. Watanabe, S. Yamaguchi, M. Yamanaka KEK, Ibaraki, Japan Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan T. Nagata ULVAC, Inc., Tsukuba, Japan
	Relations between electron beam welding parameters and appearances of weld beads are studied. It was found that a beam generator position and a welding direction affect a geometry of weld bead dramatically. Carbon including contaminants found after the chemistry are also commented.

WEPWO016	Construction of Main Linac Cryomodule for Compact ERL Project	HOM, cryomodule, linac, radiation	2349
	K. Umemori, K. Enami, T. Furuya, H. Sakai, M. Satoh, K. Shinoe KEK, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan M. Sawamura JAEA, Ibaraki-ken, Japan
	Compact ERL (cERL), which is a test facility of ERL, is under construction at KEK, in Japan. At the first stage of cERL project, electron beam will be accelerated by 30 MV at main linac region. We have developed a main linac cryomodule, which contains two L-band 9-cell superconducting cavities. Cavity assembly work was carefully done at a class-10 clean room and HOM absorbers and cold windows of input couplers were successfully mounted on the cavities. Next, the frequency tuners, thermal anchors, magnetic shields and temperature sensors and so on were assembled to the cryomodule. Then, using a clean-booth, warm windows of the input couplers are connected to the cold windows and gate valves were also attached to the both ends of the cryomodule. Finally, the cryomodule was installed into the beamline of cERL and connected to a 2K cryogenic system. Target of alignment precision of the cavities, after cooling down to 2K, are set to be within 1 mm against the beamline. The first cool-down test, followed by low power and high power measurements, is scheduled within the year 2012.

WEPWO017	Efforts on Nondestructive Inspections for SC Cavities	target, laser, SRF, cryogenics	2352
	Y. Iwashita, Y. Fuwa, M. Hashida, S. Sakabe, S. Tokita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan H. Hayano, K. Watanabe, Y. Yamamoto KEK, Ibaraki, Japan K. Otani INRS-EMT, Varennes (Québec), Canada
	The high resolution camera, so-called Kyoto Camera, inspecting the Sc cavity inner surface showed the importance of nondestructive inspections to improve yield in production of high performance SC Cavities. Further efforts have been continued for the inspection and the high resolution T-map, X-map and eddy current scanner have been developed. A radiography to detect small voids inside the Nb EBW seam with the target resolution of 0.1 mm is under investigation. We have carried out radiography tests with X-rays induced from an ultra short pulse intense laser.

WEPWO018	Status of the IHEP 1.3 GHz Superconducting RF Program for the ILC	cryomodule, SRF, vacuum, HOM	2355
	J. Gao, Y.L. Chi, J.P. Dai, R. Ge, T.M. Huang, S. Jin, C. H. Li, S.P. Li, Z.Q. Li, H.Y. Lin, Y. Liu, Z.C. Liu, Q. Ma, Z.H. Mi, W.M. Pan, Y. Sun, J.Y. Zhai, T.X. Zhao, H.J. Zheng IHEP, Beijing, People's Republic of China
	The 1.3 GHz superconducting radio-frequency (SRF) technology is one of the key technologies for the ILC. IHEP is building an SRF Accelerating Unit, named the IHEP ILC Test Cryomodule (IHEP ILC-TC1), for the ILC SRF system integration study, high power horizontal test and possible beam test in the future. In this paper, we report the components test results and the assembly preparation of this cryomodule. Processing and vertical test of the large grain low-loss shape 9-cell cavity is done. Performance of the in-house made high power input coupler and tuner at room temperature reaches the ILC specification.

WEPWO019	Development of Frequency Measurement Setup for ADS 650MHz and 1.3GHz Superconducting RF Cavities at IHEP	SRF, linac, simulation, controls	2358
	S. Jin, J. Gao, Y. Liu, Z.C. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng IHEP, Beijing, People's Republic of China
	The Accelerator Driven Sub-critical System (ADS) is under development in China, and the 650MHz β=0.82 superconducting RF cavity (SRF) has been chosen as a possible candidate to accelerate the proton bunches in the medium energy section from 360MeV to 1.5GeV [1]. In order to obtain quality management and quality assurance during fabrication, radio frequency measurements on parts and subassemblies of SRF cavities become a proper method [2]. In this paper, study on developing a new frequency measurement setup mainly for half cells, dumb-bells and end groups of ADS650MHz cavities at IHEP was reported. A digital pressure sense was assembled in the setup. Together with the simulation on the structural and frequency by ANSYS Workbench, a quantitative standard for the frequency measurement was built for the cavity fabrication. Since a 9-cell TESLA-Like cavity is also under study in the meantime, via a slight modification, the setup can be also used for it.

WEPWO021	ADS 650MHz β=0.82 Supercongducting Cavity Research Status	superconducting-cavity, proton, linac, status	2361
	Z.C. Liu, J. Gao, S. Jin, Y. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng IHEP, Beijing, People's Republic of China J.X. Wang, H. Yu, H. Yuan BIAM, Beijing, People's Republic of China
	IHEP is developing a 650MHz β=0.82 supercongducting cavity for the China ADS project. The cavity is for the energy range of from 367MeV to 1500Mev. We have chosen a five cell cavity and optimized the cavity with Epk/Eacc and Bpk/Eacc to reach high gradient. Two cavity parts were fabricated and the EB welding is in process. This paper will show the fabrication status and measurement results.

WEPWO022	IHEP03 Fabrication and Testing Status	niobium, HOM, cryomodule, status	2364
	Z.C. Liu, J. Gao, S. Jin, Y. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng IHEP, Beijing, People's Republic of China J.X. Wang, H. Yu, H. Yuan BIAM, Beijing, People's Republic of China
	IHEP is developing RF superconducting technology with different type of superconducting cavities. Tesla-like cavity which is designed by KEK is one of them. We have fabricated all the parts of the cavity using Nb material from Ningxia and cavity welding will be started soon. This paper will show the cavity fabrication procedures and measurement results.

WEPWO023	High Current Superconducting Cavity Study and Design	superconducting-cavity, linac, accelerating-gradient, electron	2366
	Z.C. Liu, J. Gao, S. Jin, Y. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng IHEP, Beijing, People's Republic of China F. Wang PKU, Beijing, People's Republic of China
	Funding: Project 11275226 supported by NSFC IHEP is developing a new type of high current superconducting cavity called slotted cavity proposed in 2010. The cavity is suitable for accelerating high beam current in Energy Recovery Linac (ERL). The cavity can extremely dump high order modes (HOMs) in the cavity to keep a high beam current threshold in the linac. We have studied and designed a three cell cavity and the fabrication is under going.

WEPWO025	Preliminary Design of 325 MHz Half-Wave Resonator	simulation, proton, controls, heavy-ion	2369
	X.Y. Zhang, X. Chen, Z.Q. Li, Q. Ma, W.M. Pan, Y. Sun, G.W. Wang, Q.Y. Wang, B. Xu, G.Y. Zhao IHEP, Beijing, People's Republic of China
	Funding: This work is supported by the "Strategic Priority Research Program" of CAS. The Half-Wave Resonator (HWR) has been widely used in proton and heavy ion accelerators, for it has particular advantages of accelerating low energy charged particles. Preliminary design of a 325 MHz β=0.12 superconducting HWR cavity has been proposed at Institute of High Energy Physics (IHEP). The basic geometric parameters choices of the cavity are based upon theoretical model and numerical calculation, and then the RF performances are optimized by extensive electromagnetic simulations. In this paper, the detailed mechanical analysis, frequency control, and the considerations for fabrication of the 325 MHz HWR cavity are also presented.

WEPWO026	HOM Parameters Simulation and Measurement Result of the IHEP02 Low-loss Cavity	HOM, dipole, damping, wakefield	2372
	H.J. Zheng, J. Gao, S. Jin, Y. Liu, Z.C. Liu, Z.H. Mi, J.Y. Zhai, T.X. Zhao IHEP, Beijing, People's Republic of China H. Yuan BIAM, Beijing, People's Republic of China
	In cavities , there exists not only the fundamental mode which is used to accelerate the beam but also higher order modes(HOMs). The higher order modes excited by beam can seriously affect beam quality, especially for the higher R/Q mode. This paper reports on recent measurements of higher order modes in the IHEP-2 low-loss SRF cavity. Using different methods, the Qext of the dangerous modes passband are got. This result is compared with TESLA result. R/Q of the first three passbands are also got by CST and compared with the results of TESLA cavity and STFBaseline cavity.

WEPWO028	10×10mm2 MgB2 Film Fabricated by HPCVD as a Candidate Material for SRF Cavit	SRF, superconductivity, radio-frequency, heavy-ion	2375
	F. He, K.X. Liu, Z. Ni, D. Xie PKU, Beijing, People's Republic of China Q. Feng Peking University, Beijing, People's Republic of China
	Magnesium diboride (MgB2) is one of candidate material for superconducting radio frequency cavities because of its good features: high transition temperature of ~39K and absence of weak links between grains which prevents other high-Tc superconducting materials, such as YBCO. Previous study of MgB2 are mainly focused on the films’ superconducting properties which are fabricated on Al2O3, SiC or some metal substrates with small scale less than 10×10 mm2. In this work we explore a technique to deposit clean and large-scale MgB2 films on Mo substrate, which is expected to provide a probable way to fabricate MgB2 thin-film cavities.. The measurement results show that its superconducting properties and mechanical behaviors are as good as those fabricated on small-scale metal substrates.

WEPWO029	Design of a SRF Quarter Wave Electron Gun at Peking University	electron, gun, simulation, SRF	2378
	P.L. Fan, K.X. Liu, S.W. Quan, F. Zhu PKU, Beijing, People's Republic of China
	Funding: Work supported by National Basic Research Project (No. 2011CB808302) and National Natural Science Funds (No. 11075007) Superconducting RF electron guns hold out the promise of very bright beams for use in electron injectors, particularly in future high average power free-electron lasers (FELs) and energy recovery linacs (ERLs). Peking University is designing a new SRF gun which is composed of a quarter wave resonator (QWR) and an elliptical cavity. Comparing to the elliptical cavity, the QWR is sufficiently compact at the same frequency and its electric field is quasi-DC. We have finished the preliminary design of the QWR cavity. The simulation shows that multipacting is not a critical issue for our cavity structure. Beam dynamic simulation of the QWR cavity is also presented. contact author : zhufeng7726@pku.edu.cn

WEPWO036	Conceptual Design of a Superfluid Superconducting Third Harmonic RF System for the SSRF Storage Ring	superconducting-cavity, cryogenics, controls, synchrotron	2381
	H.T. Hou, J.F. Liu, Z.T. Zhao SINAP, Shanghai, People's Republic of China J.F. Liu Shanghai KEY Laboratory of Cryogenics & Superconducting RF Technology, Shanghai, People's Republic of China
	Harmonic cavity can improve the beam quality through bunch size lengthening which includes providing Landau damping, suppressing coupled bunch instability and microwave instability, enhancing the beam current per bunch besides the beam lifetime improvement. A passive third harmonic superconducting cavity operating at super fluid liquid helium has been proposed for the SSRF storage ring with compromise on the required harmonic voltage, limited installation space and dissipated cryogenic power. This paper will mainly present the conceptual design of the harmonic rf system including the requirement of SSRF, a brief review on beam dynamics of harmonic rf system and the harmonic cavity choice.

WEPWO039	Prototyping of TEM-like Mode Resonators in the RAON	multipactoring, niobium, electron, simulation	2384
	H.C. Jung, M.O. Hyun, D. Jeon, H.J. Kim IBS, Daejeon, Republic of Korea
	Preliminary electric-magnetic designs of TEM-like mode resonators(a quarter wave resonator, a half wave resonator, two single spoke resonators) are accomplished for the superconducting linear accelerator in the RAON. Resonant cavities are numerically optimized using a CST MWS code to obtain higher E-field gradient along the beam line in conditions of the peak E-field and B-field is less than 30MV/m, 60mT respectively. Prototyping test of a quater wave resonator of optimum beta 0.047 using OFC(Oxygen Free Cupper)is in progress to analyze resonant frequency shifting by tolerances in fabrication process and external perturbations. It is compared with expected one using compuational codes.

WEPWO040	Design of HWR at RISP	simulation, quadrupole, electromagnetic-fields, niobium	2387
	G.-T. Park, H.J. Cha, H.C. Jung IBS, Daejeon, Republic of Korea
	At RISP, superconducting cavity resonators to accelerate the various ions in high current are being developed. In particular, hal-wave resonator (HWR) will be used for β=0.12, f=162.5 MHz. Here we present the structural analysis of HWR, which includes the prediction of resonant frequency shift during the manufacturing and testing process, stiffening measures to minimize the shift, and the tuning mechanism. The processes of welding, polishing, vacuuming, cooling (to crygenic temperature)as well as Lorentz force, helium pressure fluctuation, microphonics, and interaction with the helium vessel and tuning system will be simulated optimizing the frequency shift.

WEPWO041	Beam Commissioning Superconducting RF Cavities for PLS-II Upgrade	SRF, vacuum, storage-ring, LLRF	2390
	Y.U. Sohn, M.-H. Chun, J.Y. Huang, Y.D. Joo, S.H. Nam, C.D. Park, H.J. Park, I.S. Park, I.H. Yu PAL, Pohang, Kyungbuk, Republic of Korea
	Two superconducting RF cavities were commissioned with electron beam at PLS-II, which is upgraded machine from PLS with 3 GeV, 20 insertion devices, and now on user service. These srf cavities have been prepared during last 3 years. Each cavity was tested with higher than 2 MV rf voltage and 125 kW standing wave power at CW mode after installation at storage ring. PLS-II is on user operation with 200 mA beam current now, and on the way of beam current improvement upto 400mA, by synchrotron conditioning for beam chamber and in-vacuum udulators. Upto 200 mA beam current no beam instability from the higher order modes is observed. With top-up mode operation, the errors of amplitude of rf field and phase are recorded as 0.3% and 0.3 degree peak to peak, respectively during one day. Successful PLS-II upgrade with hardware and its designed performance will be declared at the end of 1st half user run in 2013.

WEPWO042	Dubna-Minsk SRF Technology Development Status Report	cryogenics, niobium, coupling, electron	2393
	N.S. Azaryan, Ju. Boudagov, D.L. Demin, V.V. Glagolev, G. Shirkov, G.V. Trubnikov JINR, Dubna, Moscow Region, Russia M.A. Baturitsky, N.M. Shumeiko NC PHEP BSU, Minsk, Belarus S.E. Demyanov, E.Yu. Kaniukov Scientific-Practical Materials Research Centre of the National Academy of Sciences of Belarus, Minsk, Belarus A. Ermakov, W. Singer, X. Singer DESY, Hamburg, Germany V.A. Karpovich, N.V. Liubetsky BSU, Minsk, Belarus S.V. Kolosov, A.A. Kurayev, A.O. Rak, A.K. Sinitsyn Belarus State University of Informatics and Radioelectronics (BSUIR), Minsk, Belarus S.I. Maximov, V.N. Rodionova Belarussian State University, Scientific Research Institute of Nuclear Problems, Minsk, Belarus A. Parshuto, V.S. Petrakovsky, I.L. Pobol, A.I. Pokrovsky, S.V. Yurevich, A.Yu. Zhuravsky Physical-Technical Institute of the National Academy of Sciences of Belarus, Minsk, Belarus
	In 2011 Dubna-Minsk collaboration started an activity on the development and manufacture the series of 1.3 GHz superconducting Nb cavities in the enterprises in Belarus. The current status of this work is presented in this report. Main EM characteristics of the cavity were calculated and the shop drawings for cavity fabrication were developed. Two test-benches were assembled for RF-tests of the cavities at room temperature and at liquid helium temperature. The measured SWR was about 1.01 due to special matching device developed for that. This measurement technique was applied to the single-cell cavity from FNAL at power level nearby 10 mW. Measured resonant frequency was about 1.27 GHz, while the measured Q-factor was 2.8·10⁴ at room temperature and more than 10⁸ at liquid helium temperature. To evaluate mechanical properties of sheet Nb and of model materials (Cu and Al), a number of tests were made. Series of half-cells were fabricated of Al to test the technique of hydraulic deep-drawing that will be used in production of Nb cavities. The modes for electron-beam welding of sheet Nb were explored and the first welding seams were tested. The method of chemical treatment of cavities was also elaborated.
	Poster WEPWO042 [0.897 MB]

WEPWO045	RF Multipolar Characterization of the Latest LHC Deflecting Cavities	multipole, dipole, luminosity, extraction	2402
	M. Navarro-Tapia, R. Calaga, A. Grudiev CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study (a sub-system of HL-LHC) is cofunded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. Deflecting cavity geometries considered for the Large Hadron Collider (LHC)crab scheme lack axial symmetry resulting in non-zero higher-order components of the deflecting field. A formalism to express the higher-order multipoles was developed and applied on previous cavity designs to characterize their influence on the beam stability. In this paper, the radio frequency (RF) multipoles are numerically estimated for the latest cavity geometries and compared to the older versions. A sensitivity study is carried to understand the numerical error levels and define mechanical tolerances.

WEPWO046	First Test Results of the 4-rod Crab Cavity	vacuum, niobium, pick-up, coupling	2405
	R. Calaga, L.S. Alberty Vieira, S. Calatroni, O. Capatina, E. Ciapala, L.M.A. Ferreira, E. Jensen, P. Maesen, A. Mongelluzzo, T. Renaglia, M. Therasse CERN, Geneva, Switzerland P.K. Ambattu, D. Doherty, B.D.S. Hall, C. Lingwood Cockcroft Institute, Lancaster University, Lancaster, United Kingdom G. Burt Lancaster University, Lancaster, United Kingdom
	Funding: The HiLumi LHC Design Study (a sub-system of HL-LHC) is cofunded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The first prototype crab cavity with the 4-rod geometry has undergone surface treatment and cold testing. Due to the complex geometry and unique fabrication procedure, RF validation of the field at beyond the nominal operating voltage at a sufficiently high Q0 is an important pre-requiste. Preliminary results of the first cold tests are presented along with cavity performance at different stages of the cavity processing is described.

WEPWO047	A Double Quarter-Wave Deflecting Cavity for the LHC	HOM, multipole, higher-order-mode, simulation	2408
	R. Calaga CERN, Geneva, Switzerland S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, Q. Wu, B. P. Xiao BNL, Upton, Long Island, New York, USA
	Funding: The HiLumi LHC Design Study (a sub-system of HL-LHC) is cofunded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404 An asymmetric quarter wave deflecting cavity at 400 MHz for crab crossing in the LHC was already proposed in 2011. Due to improved cancellation of on-axis longitudinal field and the higher order components of the deflecting field, a symmetric version is now considered as the baseline for the quarter wave geometry. Relevant RF properties of the symmetric cavity are compared to the original asymmetric cavity. Some aspects of input coupler design, higher order modes, multipacting and frequency tuning are also addressed.

WEPWO048	Investigation of a Ridge-loaded Waveguide Structure for CLIC X-band Crab Cavity	damping, HOM, beam-loading, impedance	2411
	V.F. Khan, R. Calaga, A. Grudiev CERN, Geneva, Switzerland
	In conventional crab cavities the TM11 mode is used to deflect the beam. In a linear collider such as CLIC, it is necessary to damp all the other modes, namely the accelerating i.e. lower order mode (LOM), same order mode (SOM) and higher order modes (HOMs). In addition to this, as the TM11 mode is not the fundamental mode, it is generally not excited with the highest shunt impedance. This necessitates damping of the high shunt impedance modes to acceptable level. Here we report on the investigation of an alternative design of the X-band crab cavity for CLIC based on ridge-loaded waveguide. In this type of cavity, the deflecting mode is the fundamental mode and has the maximum shunt impedance. However, the geometry of the cavity is chosen to optimise the ratio of group velocity to shunt impedance to minimise the effect of beam loading. The other modes are excited above the crabbing mode and are damped using wave-guides. Another advantage of this type of cavity is, unlike the conventional TM11 mode cavities, the e.m. surface fields do not peak at the iris. This provides ample margin to optimise the cavity geometry and reach the desired field distribution.

WEPWO049	A Proposal for an ERL Test Facility at CERN	linac, electron, HOM, SRF	2414
	R. Calaga, E. Jensen CERN, Geneva, Switzerland
	An energy recovery linac at 300-400 MeV is proposed as a test facility using a two-pass two-cryomodule concept as a proof of principle for a future ERL based electron-ion collider. This facility will enable both the development and validation of the required SRF technology performance and ERL specific beam dynamics essential for the future collider. Furthermore, the test facility can be used as the injector to the main linac in future. The test facility proposal, its potential uses and some aspects of the RF system are presented.

WEPWO050	Mechanical Study of 400 MHz Double Quarter Wave Crab Cavity for LHC Luminosity Upgrade	simulation, luminosity, vacuum, electron	2417
	B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, Q. Wu BNL, Upton, Long Island, New York, USA L. Alberty Vieira, R. Calaga CERN, Geneva, Switzerland T.L. Grimm Niowave, Inc., Lansing, Michigan, USA
	A prototype double quarter wave crab cavity was designed for the Large Hadron Collider luminosity upgrade. A finite element model is used to simulate the mechanical properties of the crab cavity. The results are presented and a reinforcement concept is proposed to meet the safety requirements. The reinforcement components, as well as the cavity, are presently being fabricated at Niowave Inc.

WEPWO051	Manufacture of a Compact Prototype 4R Crab Cavity for HL-LHC	niobium, luminosity, vacuum, electron	2420
	G. Burt, B.D.S. Hall, C. Lingwood Cockcroft Institute, Lancaster University, Lancaster, United Kingdom L. Alberty Vieira, R. Calaga, O. Capatina CERN, Geneva, Switzerland C.H. Boulware, D. Gorelov, T.L. Grimm, C. Krizmanich, T.S. Lamie Niowave, Inc., Lansing, Michigan, USA C. Hill, P.A. McIntosh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.A. Rimmer, H. Wang JLAB, Newport News, Virginia, USA
	Funding: This work has been funded by the EU through EUCARD and HiLumi and by STFC via the Cockcroft Institute. A prototype compact SRF deflecting cavity has been manufactured for LHC. The base of the cavity has been machined out of large grain niobium ingot to allow the manufacture of the complex rod profile. Stiffening rods have been used to increase the mechanical strength of the outer can. Details of the cavity design and manufacture will be discussed.

WEPWO053	SRF Development for a MW Proton Source at Fermi National Accelerator Laboratory	cryomodule, linac, SRF, HOM	2423
	T.T. Arkan, C.M. Ginsburg, A. Grassellino, S. Kazakov, T.N. Khabiboulline, T.H. Nicol, Y. Orlov, T.J. Peterson, L. Ristori, A. Romanenko, A.M. Rowe, N. Solyak, A.I. Sukhanov, V.P. Yakovlev Fermilab, Batavia, USA
	Funding: Work supported by the US Department of Energy Fermilab is planning a megawatt-level proton beam facility utilizing niobium superconducting RF (SRF) cavities. Project X at Fermilab will eventually provide high-intensity beams for research into the nature of matter at the "intensity frontier". Research and development in several areas will bring the SRF technology to the level needed for this application. Among developments in SRF being pursued with our national and international collaborators are 162.5 MHz half-wave resonators, 325 MHz single-spoke resonators, and two types of elliptical multi-cell 650 MHz cavities. Performance requirements for these cavities and cryomodules in continuous wave (CW) operation are extremely stringent in order to provide high accelerating gradients with acceptable total cryogenic load and overall accelerator capital and operating costs. This paper presents some highlights of the SRF R&D program and proton linac development work at Fermilab.

WEPWO054	Multistep Mechanical Analyses of Centrifugal Barrel Polishing Barrel and Cavity	simulation, SRF, acceleration, niobium	2426
	M. Chen, C.A. Cooper, L. Ristori Fermilab, Batavia, USA
	Funding: US Department of Energy Fermilab has successfully demonstrated the ability to improve the performance of damaged 1.3 GHz single cell and 9-cell Tesla–type cavities by using a modified centrifugal barrel polishing (CBP) process that leaves a mirror finish on the inside of the cavity. Fermilab now is developing and constructing a new CBP machine which can handle both 650 MHz and 1.3 GHz cavities. The new machine will have a larger moment arm and therefore impart more force on the cavity and machine. Because of these increased forces the effects on cavity supports and machine design were examined. This paper will document the multistep mechanical analyses for the CBP barrel and cavity, calculations of the fatigue life and the requirements for the structural welds.

WEPWO055	Fabrication and Testing of SSR1 Resonators for PXIE	cryomodule, linac, vacuum, beam-transport	2429

Paper

Title

Other Keywords

Page

MOPEA003

Status and Very First Commissioning of the ASTRID2 Synchrotron Light Source

vacuum, quadrupole, lattice, booster

64

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

ASTRID2 is the new 10 nm UV and soft x-ray light source at Aarhus University. It will replace the ageing source ASTRID, which will be used as the full-energy (580 MeV) booster for ASTRID2. An upgrade of the beamlines at ASTRID are presentlytaking place before being transferred to ASTRID2 until the end of 2013. In addition new beamlines and insertion devices are being procured. Presently, ASTRID2 commissioning is alternating with ASTRID operation to continue during 2013. Status in spring 2013 includes operation of most sub-systems resulting in top-up mode operation to 150 mA. The lattice have been qualifies although a re-alignment is planned. The poster will present experiences from the first commissioning and give the status of the project.

MOPEA012

Lifetime Studies at Metrology Light Source and ANKA

optics, electron, scattering, septum

88

T. Goetsch, J. Feikes, M. Ries, G. Wüstefeld
HZB, Berlin, Germany
A.-S. Müller
KIT, Karlsruhe, Germany

The Metrology Light Source (MLS)*, situated in Berlin (Germany) is an electron storage ring operating from 10⁵ MeV to 630 MeV and is serving as the national primary radiation source standard from the near infrared to the vacuum ultraviolet spectral region. In its standard user mode, the lifetime is dominated by the Touschek effect. Measurements and analysis of the Touschek lifetime as a function of beam current and RF-Voltage will be presented and compared to measurements done at the ANKA electron storage ring (Karlsruhe, Germany) which operates at 0.5 to 2.5 GeV**.
* R. Klein et al., Phys. Rev. ST-AB 11, 110701 (2008)
** A.-S. Müller et al., Energy Calibration Of The ANKA Storage Ring, In Proceedings of EPAC 2004

MOPEA018

Feasibility Study of Heavy Ion Storage and Acceleration in the HESR with Stochastic Cooling and Internal Targets

target, ion, simulation, acceleration

106

H. Stockhorst, R. Maier, D. Prasuhn, R. Stassen
FZJ, Jülich, Germany
T. Katayama
GSI, Darmstadt, Germany

Stochastic cooling of heavy ions is investigated under the constraint of the present hardware design of the cooling system and RF cavities as well as the given magnet design as foreseen for anti-proton cooling in the HESR of the FAIR facility. A bare uranium beam is injected from the collector ring CR into the HESR at 740 MeV/u. The beam preparation for an internal target experiment with cooling is outlined. The acceleration of the ion beam to 2 GeV/u is studied under the basic condition of the available cavity voltages and the maximum magnetic field ramp rate in the HESR. The cooling simulations include the beam-target interaction due to a Hydrogen and Xenon target. Diffusion due to Schottky and thermal noise as well as intra beam scattering is accounted for. Due to the higher charge states of the ions Schottky particle noise power becomes an important issue. The analysis considers the electronic power limitation to 500 W in case of momentum cooling. Fast Filter cooling is only available if the revolution harmonics do not overlap in the cooling bandwidth. Since overlap occurs for lower energies the application of the Time-Of-Flight (TOF) momentum cooling method is discussed.

MOPEA030

Status of UVSOR-III

injection, undulator, vacuum, sextupole

142

N. Yamamoto
Nagoya University, Nagoya, Japan
T. Konomi
UVSOR, Okazaki, Japan

Construction of the Central Japan Synchrotron Radiation (SR) Facility has been completed in the Aichi area of Japan, and the beam commissioning was started in Spring of 2012. Up to now, it is confirmed that the 1.2 GeV storage ring works with 300 mA Top-up mode. The key equipments of the accelerators are a compact electron storage ring with the ability to supply hard X-rays and full energy injectors for the top-up operation. The accelerators consist of an electron storage ring, a booster synchrotron ring, and an injector linac. In this prezentation, the present status of the accelerators are reported.

MOPEA039

Beam Commissioning and Neutron Radiography on a High Current Deuteron RFQ

rfq, neutron, target, ECR

163

Y.R. Lu, J. Chen, J.E. Chen, S.L. Gao, Z.Y. Guo, F.J. Jia, G. Liu, S.X. Peng, H.T. Ren, W.L. Xia, X.Q. Yan, K. Zhu
PKU, Beijing, People's Republic of China
S.Q. Liu, S. Wang, J. Zhao, B.Y. Zou
State Key Laboratory of Nuclear Physics and Technology, Beijing, Haidian District, People's Republic of China

Funding: Supported by NSFC 11079001 and Peking University
The high current deuteron RFQ has been developed and widely used in many projects, especially for accelerator based neutron source and its application. This paper reviews not only the recent developments in the world wide, also presents the beam dynamics, structure design ,RF full power test, beam commissioning of PKUNIFTY, which is consisted of a high current very compact ECR source, a 201.5MHz four-rod deuteron RFQ, thicker beryllium target and its moderating, collimation and neutron radiography system. RF and beam commissioning with duty cycle of 4% show the RFQ inter-vane voltage reaches 70kV at about 240kW, the delivered deuteron peak beam current is about 12mA at 290kW with the beam transmission of about 60%. The improvement of transmission is going on. The initial neutron radiography commissioning has been carried out. The results will promote the future development of small accelerator based neutron source.

MOPEA040

Study of Geometry Dependent Multipacting of a Superconducting QWR

accelerating-gradient, electron, simulation, vacuum

166

K. Zhou, X.Y. Lu, X. Luo, S.W. Quan, L. Yang, Z.Y. Yao
PKU, Beijing, People's Republic of China

Funding: The Major Research Plan of National Natural Science Foundation of China
A superconducting quarter wave resonator (QWR) of frequency=162.5 MHz and β=0.085 has been designed at Peking University. This paper focus on the multipacting (MP) study for the QWR with CST Particle Studio. The simulation results for the initial designed model reveal that there is no sign of MP with its normal operating accelerating gradients in the range of 6-8 MV/m. The accelerating gradient range that may incur MP is from about 1.4 MV/m to 3.2 MV/m, and the places where MP may be encountered are mainly located at the top part of the QWR. So the effect of different top geometries on MP has also been studied in depth. Our results show that inward convex round roof is better than other round roofs, and plane roofs have an obvious advantage over round roofs on the suppression of MP in general. While considering the optimization of its electromagnetic (EM) design, our initial designed model is also acceptable.

MOPEA045

Performance Optimization and Upgrade of the SSRF Storage Ring

storage-ring, emittance, optics, injection

178

Z.T. Zhao, B.C. Jiang, Y.B. Leng, S.Q. Tian, L. Yin, W.Z. Zhang
SINAP, Shanghai, People's Republic of China

The SSRF storage ring achieved its design performance goal in 2008, in the following years its performance was optimized and improved, including implementing top-up operation and low emittance lattice configuration as well as other attempts like fast orbit feedback and low alpha mode. In order to meet the requirements of accommodating more beamlines and high demanding performance in its phase-II beamline project, the SSRF storage ring is being upgraded with a design based on superbend based lattice and a third harmonic RF cavity system. This paper presents the main optimization works and the upgrade design considerations on the SSRF storage ring performance.

MOPEA056

Measuring and Improving the Momentum Acceptance and Horizontal Acceptance at MAX III

lattice, electron, vacuum, storage-ring

205

A. Hansson, Å. Andersson, J. Breunlin, G. Skripka, E.J. Wallén
MAX-lab, Lund, Sweden

Lifetime measurements for varying horizontal scraper positions performed at different RF frequencies suggested a horizontal aperture restriction in the MAX III synchrotron light source. A combination of local orbit distortions and horizontal scraper measurements pinpointed the location of the horizontal aperture restriction to the center of the main cavity straight section. The aperture restriction was determined to be located 10.4 ± 0.3 mm from the beam center. The precise result was achieved by measurements and calculations of the Touschek lifetime as a function of the main cavity voltage. Realignment of the main cavity increased the average lattice momentum acceptance from 0.0116 ± 0.0003 to 0.0158 ± 0.0003 and the horizontal acceptance from 26 ± 2 × 10^-6 m to larger than 44 ± 2 × 10^-6 m. The increase in momentum acceptance increased the lifetime in MAX III by a factor of two.

MOPEA057

Studies of the Electron Beam Lifetime at MAX III

scattering, electron, vacuum, emittance

208

A. Hansson, Å. Andersson, J. Breunlin, G. Skripka, E.J. Wallén
MAX-lab, Lund, Sweden

MAX III is a 700 MeV 3rd generation synchrotron light source located at the MAX IV Laboratory in Sweden. The lifetime in the storage ring is lower than originally envisaged. From vertical scraper measurements the lifetime contributions at 300 mA stored current have been determined. The lifetime is mainly limited by the Touschek lifetime, which is lower than its design value, whereas the vacuum lifetime is close to the expected value. The low Touschek lifetime is explained by a lower than design emittance ratio and momentum acceptance in the storage ring.

MOPEA061

Operation Experience at Taiwan Light Source

kicker, SRF, diagnostics, injection

220

Y.-C. Liu, H.H. Chen, H.C. Chen, S. Fann, S.J. Huang, J.A. Li, C.C. Liang, Y.K. Lin, Y.-H. Lin, M.-S. Yeh
NSRRC, Hsinchu, Taiwan

A matrix structure has been implemented for the purpose of successful operation of TLS and continuous progress of Taiwan Photon Source (TPS) construction. A dedicated and flexible manpower distribution has proven it could keep as same performance of TLS operation as possible. We will summarize the machine operation experience at TLS during TPS civil construction period.

MOPFI001

Characterization of a Superconducting Pb Photocathode in a SRF Gun Cavity

cathode, laser, gun, electron

279

R. Barday, T. Kamps, O. Kugeler, A. Neumann, M. Schmeißer, J. Völker
HZB, Berlin, Germany
P. Kneisel
JLAB, Newport News, Virginia, USA
R. Nietubyć
NCBJ, Świerk/Otwock, Poland
J.K. Sekutowicz
DESY, Hamburg, Germany
J. Smedley
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Bundesministerium für Bildung und Forschung and Land Berlin. The Pb deposition activity is supported by EuCARD.
Photocathodes are a limiting factor for the next generation of ultra-high brightness photoinjector driven accelerators. We studied the behavior of a superconducting Pb cathode in the cryogenic environment of a superconducting rf gun cavity related to the quantum efficiency, its spatial distribution and the work function. Cathode surface contaminations can modify the performance of the photocathodes as well as the gun cavity. We discuss the possibilities to remove these contaminations.

MOPFI002

Results from Beam Commissioning of an SRF Plug-gun Cavity Photoinjector

laser, emittance, cathode, gun

282

M. Schmeißer, R. Barday, A. Burrill, A. Jankowiak, T. Kamps, J. Knobloch, O. Kugeler, P. Lauinger, A. Neumann, J. Völker
HZB, Berlin, Germany
P. Kneisel
JLAB, Newport News, Virginia, USA
R. Nietubyć
NCBJ, Świerk/Otwock, Poland
J.K. Sekutowicz
DESY, Hamburg, Germany
I. Will
MBI, Berlin, Germany

Superconducting rf photoelectron injectors (SRF guns) hold the promise to deliver high brightness, high average current electron beam for future lightsources or other applications demanding continuous wave operation of an electron injector. This paper discusses results from beam commissioning of a hybrid Pb coated plug-gun Nb cavity based SRF photoinjector for beam energies up to 3 MeV at Helmholtz-Zentrum Berlin. Emittance measurements and transverse phase space characterization with solenoid-scan and pepperpot methods will be presented.

MOPFI003

SRF Photoinjector Cavity for BERLinPro

cathode, SRF, gun, HOM

285

A. Neumann, W. Anders, A. Burrill, A. Frahm, T. Kamps, J. Knobloch, O. Kugeler
HZB, Berlin, Germany
E.N. Zaplatin
FZJ, Jülich, Germany

For the funded BERLinPro project, a 100 mA CW-driven SRF energy recovery linac, a SRF photoinjector cavity has to be developed which delivers a small emittance, 1 mm*mr, high brightness beam while accelerating a high average current within given high power limitations. To achieve these goals the injector is being developed in a three stage approach. In the current design step a cavity shape was developed which fulfills the beam dynamics requirements, implements a high quantum efficiency normal conducting photocathode with the HZDR choke and insert design and allows for beam studies at currents up to 4 mA. This paper will describe the RF design process, higher order mode studies and final mechanical calculations prior to the cavity production.

MOPFI004

The Injector Layout of BERLinPro

emittance, cathode, linac, gun

288

B.C. Kuske, M. Abo-Bakr, V. Dürr, A. Jankowiak, T. Kamps, J. Knobloch, P. Kuske, S. Wesch
HZB, Berlin, Germany

Funding: The Bundesministerium für Bildung und Forschung (BMBF) and the state of Berlin, Germany.
BERLinPro is an Energy Recovery Linac Project running since 2011 at the HZB in Berlin. The key component of the project is the 100mA superconducting RF photocathode gun under development at the HZB since 2010. Starting in 2016 the injector will go into operation providing 6 MeV electrons with an emittance well below 1mm mrad and bunches shorter than 4ps. 2017 the 50MeV linac will be set up and full recirculation is planned for 2018. The injector design including a dogleg merger has been finalized and is described in detail in this paper. Emphasis is laid on the final layout including collimators and diagnostics and performance simulations of two different gun cavities and first tolerance studies.

MOPFI020

Cold Test of the Coaxial Cavity for Thermionic Triode Type RF Gun

gun, resonance, electron, FEL

324

T. Konstantin, Y.W. Choi, T. Kii, R. Kinjo, K. Masuda, M. Mishima, K. Nagasaki, H. Negm, H. Ohgaki, K. Okumura, M. Omer, S. Shibata, K. Shimahashi, K. Yoshida, H. Zen
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

A thermionic rf gun has several advantages as compared to photocathode gun. Such as low cost, high averaged current and simple operation. However a thermionic rf gun has a significant disadvantage in form of back bombardment effect. The KU-FEL facility is an oscillator type FEL, which uses a thermionic 4.5 cell S-band RF gun for electron beam generation. The back bombardment effect causes increasing current in macropulse, which limits the gain of the FEL. In order to mitigate the current increase we plan to modify thermionic rf gun to triode type rf gun. Therefore an additional rf cavity has been designed. This cavity has separate rf power supply with amplitude and phase control. By this means we can properly adjust the injection of electrons into the main gun body. According to simulations the triode type gun can reduce 80% of back streaming electron energy*. The cold tests of the first prototype have revealed deviation from designed values**. Based on the tests of the first prototype new prototype with integrated mechanism for resonance tuning has been designed and fabricated. In this work we report the cold test of the redesigned prototype of the coaxial rf cavity.
* K. Masuda et al. Proceedings of FEL 2006, BESSY Berlin.
** M. Takasaki et al. Proceedings of FEL 2010, Malbö

MOPFI033

Commissioning Results and Progress of a Helium Injector for Coupled RFQ and SFRFQ Project at Peking University

ion, rfq, ion-source, emittance

357

J. Chen, J.E. Chen, S.L. Gao, Z.Y. Guo, Y.T. Luo, S.X. Peng, H.T. Ren, Z. Wang, Z.H. Wang, W.L. Xia, Y. Xu, A.L. Zhang, T. Zhang, J. Zhao
PKU, Beijing, People's Republic of China

At Peking University (PKU) a new helium injector for coupled radio frequency quadrupole(RFQ) and separated function radio frequency quadrupole(SFRFQ) within one cavity, so called as coupled RFQ & SFRFQ, was designed recently*. It will provide a 30keV 20mA He⁺ beam whose emittance is less than 0.15 π.mm.mrad for the accelerator. It is a combination of a 2.45GHz PKU PMECRIS (Permanent Magnet ECRIS) and a 1.16 m long LEBT. Within the 1.16 m LEBT, 2 solenoids, 2 steering magnets, a kicker, a space charge compensation section, a collimator, two vacuum valves, a Faraday cup and an ACCT are installed. The manufacture has been completed and the commissioning is on the way. In this paper we will address the commissioning results and its progress.
* Haitao Ren, et al., A Helium Injector for Coupled RFQ and SFRFQ Cavity Project at Peking University. Proc. LINAC’12, Paper TUPB034, Israel, 2012

MOPFI044

VHF Gun Research at SINAP

gun, electron, FEL, vacuum

380

Q. Gu, L. Chen, W. Fang, G.Q. Lin
SINAP, Shanghai, People's Republic of China

The R&D work on the high power THz based on energy recovery linac (ERL) has been carried out in Shanghai Institute of Applied Physics (SINAP). One of the key components for the ERL is the high brightness electron source. The low frequency gun technology has been adopted, by comparing with the SRF gun and DC gun. In this paper, the design and cold test of a 250MHz gun will be presented.

MOPFI045

Studying of Multipacting in Micro-pulse Electron Gun

electron, gun, simulation, resonance

383

L. Liao, W. Fang, Q. Gu, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China

Depending on the complexity of multipacting phenomenon, more works are focused on the occurrence of multipacting in the micro-pulse electron gun. In this paper, the multipacting resonance condition is determined in a reentrant cavity model of the gun. The resonance parameters work as the input for VORPAL simulations in order to achieve a steady state saturation in the cavity. The simulation results showed that the gun can give rise to electrons beam with high currents and short pulses.

MOPFI068

High Repetition Rate Highly Stable S-band Photocathode Gun for the CLARA Project

gun, laser, electron, cathode

437

B.L. Militsyn, L.S. Cowie, P. Goudket, S.P. Jamison, J.W. McKenzie, K.J. Middleman, R. Valizadeh, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
V.V. Paramonov
RAS/INR, Moscow, Russia
M.D. Roper
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

Compact Linear Accelerator for Research and Applications (CLARA) is a 250 MeV electron facility which is under development at STFC ASTeC. The CLARA photo-injector is based on a RF photocathode gun operating with metal photocathodes and driven by a third harmonic of Ti: Sapphire laser (266 nm). The injector will be operated with laser pulses with an energy of up to 2 mJ, pulse durations down to 180 fs FWHM and a repetition rate of up to 400 Hz. In order to investigate performance of different photocathodes the gun is equipped with a load-lock system which would allow replacement of the photocathodes. Duration and emittance of electron bunches essentially depends on the mode of operation and vary from 0.1 ps at 20 pC to 5 ps at 200 pC and from 0.2 to 2 mm mrad respectively. Requirements for the stability of beam arrival time at the CLARA experimental area are extremely high and vary from hundreds down to tenths femtoseconds. In the presented article we analyse stability of the guns with 1.5 and 2.5 cell and the beam quality delivered by a gun with coaxial and waveguide coupler and analyse possibility of injection time stabilisation with low level RF and optical feedback system.

MOPME019

Alignment Detection Study using Beam Induced HOM at STF

HOM, dipole, alignment, cryomodule

509

A. Kuramoto
Sokendai, Ibaraki, Japan
H. Hayano
KEK, Ibaraki, Japan

STF accelerator using L-band photocathode RF Gun and two superconducting cavities is under operation for R&D of ILC. Electron beam extracted from the RF Gun is accelerated to 40 MeV by two superconducting cavities. Cavity alignment requirements for ILC are less than 300um offset and 300urad tilt with respect to cryomodule. It is necessary to measure their offset and tilt inside of cryomodule. Cavity offset has been already measured by using beam induced HOM at FLASH in DESY. Cavity deformation during assembly and by cooling contraction has not been examined yet. We measured HOM signals to detect their tilt and bending. TE111-6 which has high impedance is used to estimate cavity offset. To find cavity tilt and bending, we selected pi over nine mode in the first dipole passband (TE111-1) and beam pipe modes. From information of TE111-1 which has maximum radial electric field in the middle cell, we can get electrical center of middle cell. At beam pipes, electrical center can be found by using beam pipe modes. Combinations of these electrical centers tell us cavity tilt and bending. We will present results of these TE111-1 and beam pipe mode together with beam trajectory information.

MOPME026

Beam Monitor Layout for Future ACS Section in J-PARC Linac

linac, DTL, beam-transport, monitoring

529

A. Miura, M. Ikegami, H. Oguri
JAEA/J-PARC, Tokai-mura, Japan

In J-PARC Linac, an energy and intensity upgrade project has started since 2009 using Annular Coupled Structure (ACS) cavities. With this upgrade, the design peak current will be increased from the present 30 mA to 50 mA, and the energy from 181 MeV to 400 MeV. Along with these significant upgrades of the beam parameters, beam monitors should be followed. Also, the bunch shape monitor and new beam loss monitoring system will be employed for the new beam line. Newly fabricated devices will be delivered in the ACS beam line. And beam monitor layout of the upstream and downstream of ACS beam line will be modified. In this paper, we introduce the development of the beam diagnostic devices for the project and the new designed beam monitor layout.

MOPME040

Cavity-based Multi-parameter Beam Diagnostics at HLS

quadrupole, emittance, diagnostics, gun

559

Q. Luo, B.G. Sun
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Natural Science Foundation of China (11005106)
Recent developments of the fourth generation light sources needs precious control of beam parameters, such as beam position, transverse emittance, beam density, bunch length, etc.. Non-destructive on-line beam diagnostic methods are then required. As an example, the cavity beam multi-parameter monitor system designed for the HLS photocathode RF electron gun consists of a beam position monitor, a beam quadrupole moment monitor and a beam density and bunch length monitor. 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. Beam quadrupole moment monitor system consists of a square pill-box quadrupole moment cavity, a cylindrical pill-box reference cavity and a waveguide coupling network. TM0n0 modes of cavity can be used to work out beam density and bunch length simultaneously. To simplify the design and suppress the whole system here, we use the reference cavity of beam position monitor as beam density and bunch length signal pick-up.

MOPME051

Development of Cavity Beam Position Monitor System

FEL, simulation, coupling, electron

586

B.P. Wang, Y.B. Leng, Y.B. Yan, L.Y. Yu, R.X. Yuan, W.M. Zhou
SINAP, Shanghai, People's Republic of China

Shanghai soft X-ray free electron laser (SXFEL) facility requires beam position resolution better than 1 μm in the undulator sections. Cavity BPM system, feasible in obtaining sub micron position resolution, has been developed to achieve the goal. Two cavity prototypes with high Q and low Q were designed and fabricated. The relevant dedicated electronic, which could cover the two types of cavity BPMs, also have been developed. Fast fourier transform (FFT) and digital down converted based algorithms were implemented. The beam test of the whole system has been scheduled on the Shanghai deep ultraviolet (SDUV) FEL facility. The cavity design, electronic architecture, achieved performance during beam test will be presented.

MOPME058

DEVELOPMENT OF A CAVITY-TYPE BEAM POSITION MONITORS WITH HIGH RESOLUTION FOR ATF2

dipole, simulation, electron, extraction

604

S.W. Jang, E.-S. Kim
KNU, Deagu, Republic of Korea
Y. Honda, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan

We have developed a high resolution beam position monitors for ATF2 at KEK, which is an accelerator test facility for International Linear Collider(ILC). The main goals of ATF2 are achievement of 37nm beam size and 2nm beam position resolution for beam stabilization. For these goals, low-Q IP-BPM(Interaction Point Beam Position Monitor) with latency of 20 ns are being developed. In this paper, we will describe about design of Low-Q IP-BPM, the basics test results as RF test and BPM sensitivity test. Electronics for Low-Q IP-BPM will be also described.

MOPME073

Measurement of Schottky-like Signals from Linac Bunched Hadron Beams for Momentum Spread Evaluation

linac, synchrotron, pick-up, bunching

649

P. Kowina, P. Forck, R. Singh
GSI, Darmstadt, Germany
F. Caspers
CERN, Geneva, Switzerland
R. Singh
TEMF, TU Darmstadt, Darmstadt, Germany

We present a novel method for the measurement of Linac beam parameters in the longitudinal phase space. The longitudinal momentum spread can be evaluated by means of Schottky type signal analysis of bunched beams. There is a close similarity between a repetitive Linac bunch train and a circulating beam with a single short batch in a large machine like the LHC. A dedicated longitudinal cavity pick-up was used in the Linac where resonance frequency and Q-value were carefully selected in order to get an optimum compromise between the unavoidable coherent signal and the desired incoherent part of the beam spectrum. A time domain gating similar to the 4.8 GHz LHC Schottky front-end is applied. As a cross-check of the validity of the interpretation in terms of momentum spread, the Linac beam is analyzed in the downstream synchrotron using standard Schottky methods. In principle, this approach can be understood as an extension of Schottky analysis for circular machines with a perfect “mixing” between subsequent bunch trains. This contribution describes the test set-up and discusses the results of the measurements with a heavy ion beam.

MOPWA052

Short Range Wakefield Measurements of High Resolution RF Cavity Beam Position Monitors at ATF2

wakefield, quadrupole, simulation, extraction

792

J. Snuverink, S.T. Boogert, F.J. Cullinan, Y.I. Kim, A. Lyapin
JAI, Egham, Surrey, United Kingdom
K. Kubo, T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
G.R. White
SLAC, Menlo Park, California, USA

Cavity beam position monitors (CBPM) have been used in several accelerator facilities and are planned to be used in future accelerators and light sources. High position resolution up to tens of nanometres has been achieved, but short range wakefields are a concern, especially for small beam emittances. This paper presents the wakefield calculations as well as the first measurements of the CBPM-generated short range wakefields performed at the Accelerator Test Facility (ATF2).

MOPWA055

Status of Higher Order Mode Beam Position Monitors in 3.9 GHz Superconducting Accelerating Cavities at FLASH

HOM, wakefield, dipole, diagnostics

798

P. Zhang, R.M. Jones, I.R.R. Shinton
UMAN, Manchester, United Kingdom
N. Baboi, P. Zhang
DESY, Hamburg, Germany
T. Flisgen, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: This work was partially funded by the European Commission under the FP7 Research Infrastructures grant agreement No.227579.
Higher order mode (HOM) beam position monitors (BPM) are being developed for the 3.9GHz third harmonic superconducting accelerating cavities at FLASH. The transverse beam position in a cavity can be determined utilizing beam-excited HOMs based on dipole components. The existing couplers used for HOM suppression provide the necessary signals. The diagnostics principle is similar to a cavity BPM, but requires no additional vacuum instruments on the linac. The challenges lie in the dense HOM spectrum arising from couplings of the majority HOMs amongst the four cavities in the cryo-module. HOMs with particularly promising diagnostics features were evaluated using various devices with various analysis methods. After careful theoretical and experimental assessment of HOMs, multi-cavity modes at ~5GHz were chosen to provide a global position over the complete module with superior resolution (~20μm) while trapped modes at ~9GHz provide local position in each cavity with comparable resolution (~50μm). A similar HOM-BPM system is planned for the European XFEL 3.9GHz module with 8 cavities. This paper reviews both the current status and the future prospects of HOM-BPMs in 3.9GHz cavities.

MOPWA058

Cavity Beam Position Monitor at Interaction Point Region of Accelerator Test Facility 2

feedback, quadrupole, optics, focusing

807

Y.I. Kim, D.R. Bett, N. Blaskovic Kraljevic, P. Burrows, G.B. Christian, M.R. Davis, A. Lyapin
JAI, Oxford, United Kingdom
S.T. Boogert
Royal Holloway, University of London, Surrey, United Kingdom
J.C. Frisch, D.J. McCormick, J. Nelson, G.R. White
SLAC, Menlo Park, California, USA
Y. Honda, T. Tauchi, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Nanometre resolution cavity beam position monitors (BPMs) have been developed to measure the beam position and linked to a feedback system control the beam position stability within few nanometres in the vertical direction at the focus, or interaction point (IP), of Accelerator Test Facility 2 (ATF2). In addition, for feedback applications a lower-Q and hence faster decay time system is desirable. Two IPBPMs have been installed inside of IP chamber at the ATF2 focus area. To measure the resolution of IPBPMs two additional C-band cavity BPMs have been installed one upstream and one downstream of the IP. One cavity BPM has been installed at an upstream image point of IP. The performance of the BPMs is discussed and the correlation between IP and image point positions is presented along with a discussion of using these BPMs for position stabilisation at the IP.

MOPWA064

Microwave Resonator Diagnostics of Electron Cloud Density Profile in High Intensity Proton Beam

electron, proton, vacuum, simulation

825

Y.-M. Shin, J. Ruan, C.-Y. Tan, J.C.T. Thangaraj, R.M. Zwaska
Fermilab, Batavia, USA

We have developed an novel technique to accurately estimate the density of dilute electron clouds emitted from high intensity proton beams. The strong phase shift enhancement from multiple reflections of standing microwaves in a resonating beam pipe cavity has been demonstrated with numerical modeling using dielectric approximation and e S-parameter measurements. The equivalent dielectric simulation showed a ~ 10 times phase shift enhancement (Pi-mode, 1.516 GHz) with the cavity beam pipe compared to the waveguide model. The position-dependence of the technique is investigated by overlapping the field distributions of harmonic resonances. The simulation with various positions of dielectric insertions confirmed that resonance peaks in phase-shift spectra corresponding to the relative distance between field-nodes and electron cloud position, which allows for one-dimensional mapping. Preliminary experimental studies based on a bench-top setup confirm the results of the simulation showing that thicker reflectors enhance the phase-shift measurement of the electron cloud density.

MOPWA070

Beam Position Monitor within the Cornell Energy Recovery Linac Cavity Assembly

HOM, coupling, pick-up, RF-structure

840

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

In an energy recovery Linac (ERL) the low energy beam is very sensitive to deflections due to the RF fields as it passes through the accelerator cavities. Therefore, to avoid the possible effects of beam breakup, it will be important to determine the optimum transverse position for the beam within the first several sets of cavity cells in the cryostat assembly and to maintain this position over long periods. As a result a beam position monitor (BPM) has been designed to be located between the higher-order modes (HOM) loads and the seven-cell RF structures. This BPM’s design reduces the coupling of RF power from the fundamental mode and HOMs into the BPM, while maintaining acceptable position sensitivity and resolution. We analyzed the coupling of the probe to the HOMs of realistically shaped cavities by generating geometries for hundreds of cavities having small shape variations from the nominal dimensions consistent with present machining tolerances, and solved for their monopole and dipole spectra. Our results show that the peak, dissipated power within BPM cables, which pass through the cryostat, is well within the permissible levels.

MOPWO002

PTCC: New Beam Dynamics Design Code for Linear Accelerators

linac, space-charge, simulation, plasma

882

Y. N. Nour El-Din, T.M. Abuelfadl
Cairo University, Giza, Egypt

Funding: Work supported by the Egyptian Science and Technology Development Fund (STDF) No. 953.
A fast and accurate beam dynamics design code, named PTCC (Particle Tracking Code in C) is developed to simulate particles dynamic in linear accelerators. PTCC solves the relativistic equations of motion for the macro-particles when subjected to electromagnetic fields excited in RF cavities. The self-fields of the particles are also part of the electromagnetic fields through which the particles are tracked. Self-fields are calculated using a modified 2D cylindrically symmetric mesh based method, making use of beam and field symmetry to provide fast simulation. The code has been benchmarked with the well known code ASTRA which is used mainly in simulations of next generation FEL linacs. PTCC provides a new tool for designing buncher section of linear accelerators that convert DC beam into bunches. New buncher design tool and benchmark results of PTCC with ASTRA are presented.

MOPWO003

Multibunch Tracking Code Development to Account for Passive Landau Cavities

electron, damping, impedance, radiation

885

M. Klein, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

The MAX IV 3 GeV storage ring will achieve an ultra-low horizontal emittance of 0.24 nm rad by using a multibend achromat lattice. Passive harmonic cavities are introduced to relax the Touschek-lifetime and intrabeam scattering issues as well as fight collective beam instabilities via Landau damping. Since instabilities occur during injection, when the passive harmonic cavity potential is also time varying, it became important to simulate this transient process. The most promising approach was considered to be multibunch tracking which also allows for an arbitrary filling pattern. Since every bunch is represented by numerous macroparticles, internal motions as well as microstructures in the charge distribution can be followed.

MOPWO006

Eigenmode Computation for the GSI SIS18 Ferrite Cavity

resonance, heavy-ion, ion, synchrotron

894

K. Klopfer, W. Ackermann, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Supported by GSI
At the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt the heavy-ion synchrotron SIS18 is operated to further accelerate stable nuclei of elements with different atomic numbers. Two ferrite-loaded cavity resonators are installed within this ring. During the acceleration phase their resonance frequency has to be adjusted to the revolution frequency of the heavy-ions to reflect their increasing speed. To this end, dedicated biased ferrite-ring cores are installed inside the cavities for a broad frequency tuning. By properly choosing a suited bias current, the differential permeability of the ferrite material is modified, which finally enables to adjust the eigenfrequency of the resonator system. Consequently, the actual resonance frequency strongly depends on the magnetic properties of the ferrites. The goal of the current study is to numerically determine the lowest eigensolutions of the GSI SIS18 ferrite-loaded cavity. For this purpose, a new solver based on the Finite Integration Technique has been developed.

MOPWO007

Numerical Calculation of Electromagnetic Fields in Acceleration Cavities Under Precise Consideration of Coupler Structures

dipole, electromagnetic-fields, impedance, resonance

897

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

Funding: Work supported by BMBF under contract 05H12RD5
The acceleration with superconducting radio frequency cavities requires dedicated couplers to transfer energy from the radio frequency source to the beam. Simultaneously, higher order mode couplers are installed to effectively suppress parasitic modes. Therefore, the numerical eigenmode analysis based on real-valued variables is no longer suitable to describe the dissipative acceleration structure. At the Computational Electromagnetics Laboratory (TEMF) a robust parallel eigenmode solver to calculate the eigenmodes in the lossy acceleration structure is available. This eigenmode solver is based on complex-valued finite element analysis and utilizes basis functions up to the second order on curved tetrahedral elements to enable the high precision elliptical cavity simulations. The eigenmode solver has been applied to the TESLA 1.3 GHz accelerating cavity to determine the resonance frequency, the quality factor and the corresponding field distribution for all 192 eigenmodes up to the 5th dipole passband (3.12 GHz).

MOPWO008

Eigenmode Computation for Elliptical Cavities Subject to Geometric Variation using Perturbative Methods

simulation, factory, higher-order-mode, SRF

900

K. Brackebusch, 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 05K10H.
Parametric studies of geometric variations are an essential part of the performance optimization and error estimation in the design of accelerator cavities. Using common eigenmode solvers the analysis of intentional and undesired geometric perturbations tend to be very extensive since any geometric variation involves an entire eigenmode recomputation. Perturbative methods constitute an efficient alternative for the computation of a multitude of moderately varying geometries. They require a common eigenmode computation of solely one (so called unperturbed) geometry and allow for deriving the eigenmodes of similar but modified (so called perturbed) geometries from these unperturbed eigenmodes. In [*],[**] the practicability of perturbative methods was already proven by means of simple cavity geometries. In this paper we investigate the applicability and efficiency for practically relevant cavities. For this, basic geometric parameters of elliptical cavities are varied and the respective eigenmodes are computed by using perturbative as well as common methods. The accuracy of the results and the computational effort of the different methods are compared.
*K. Brackebusch, H.-W. Glock, U. van Rienen, WEPPC096, IPAC 2011
**K. Brackebusch, U. van Rienen, MOPPC062, IPAC 2012

MOPWO010

Machine Protection Studies for a Crab Cavity in the LHC

simulation, beam-losses, luminosity, collimation

906

B. Yee-Rendon, R. Lopez-Fernandez
CINVESTAV, Mexico City, Mexico
T. Baer, J. Barranco, R. Calaga, A. Marsili, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland

Funding: US-LARP and CONACYT
Crab cavities (CCs) apply a transverse kick that rotate the bunches so as to have a head-on collision at the interaction point (IP). Such cavities were successfully used to improve the luminosity of KEKB. They are also a key ingredient of the HL-LHC project to increase the luminosity of the LHC. As CCs can rapidly change the particle trajectories, machine protection studies are required to assess the beam losses due to fast CC failures. In this paper, we discuss the effect of rapid voltage or phase changes in a CC for the HL-LHC layout using measured beam distributions from the present LHC.

MOPWO053

Evolution of the Tracking Code PLACET

wakefield, simulation, linac, collider

1014

A. Latina, Y.I. Levinsen, D. Schulte
CERN, Geneva, Switzerland
J. Snuverink
JAI, Egham, Surrey, United Kingdom

The tracking code PLACET simulates beam transport and orbit corrections in linear accelerators. It incorporates single- and multi-bunch effects, static and dynamic imperfections. A major restructuring of its core has resulted in an improvement in its modularity, with some immediate advantages: its tracking core, which is one of the fastest available for this kind of simulations, is now interfaced toward three different scripting languages to offer great simulation capabilities: Tcl/Tk, Octave and Python. These three languages provide access to a vast library of scientific tools, mechanisms for parallel computing, and access to Java interfaces for control systems (such as that of CTF3). Also, new functionalities have been added: parallel tracking to exploit modern multicore CPUs, the possibility to track through the interaction region in presence of external magnetic fields (detector solenoid) and higher order imperfections in magnets. PLACET is currently used to simulate the CLIC Drive Beam, the CLIC Main Beam, CTF3, FACET at SLAC, and ATF2 at KEK.

TUYB102

Summary of the ILC R&D and Design

positron, electron, linac, damping

1101

B.C. Barish
CALTECH, Pasadena, California, USA

This talk should provide a summary of the main activities of ILC-GDE since 2005, and an overview of the Technical Design Report with prospects for the next steps for the future.

Slides TUYB102 [6.544 MB]

TUOCB103

Quasi Traveling Wave Side Couple RF Gun for SuperKEKB

gun, emittance, focusing, cathode

1117

T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou
KEK, Ibaraki, Japan

We are developing a new RF gun for SuperKEKB. High charge low emittance electron and positron beams are required for SuperKEKB. We will generate 7.0 GeV electron beam at 5 nC 20 mm-mrad by J-linac. In this linac, a photo cathode S-band RF gun will be used as the electron beam source. For this reason, we are developing an advanced RF gun. We have tested a Disk and Washer (DAW) type RF gun. Additionally, another new RF gun which has two side coupled standing wave field is developed. We call it quasi traveling wave side couple RF gun. This gun has a strong focusing field at the cathode and the acceleration field distribution also has a focusing effect. The design of RF gun and experimental results will be shown.

Slides TUOCB103 [2.959 MB]

TUODB101

Studies on An S-band Bunching System with Hybrid Buncher

bunching, linac, electron, gun

1120

S. Pei, O. Xiao
IHEP, Beijing, People's Republic of China

Generally, a standard bunching system is composed by a SW pre-buncher, a TW buncher and a standard accelerating section. However, there is one way to simplify the whole system to some extent by using the hybrid buncher, which is a combined structure of the SW pre-buncher and the TW buncher. Here the beam dynamics studies on an S-band bunching system with hybrid buncher is presented, simulation results shows that similar beam performance can be obtained at the linac exit by using this kind of bunching system rather than the standard one. In the meantime, the structure design of the hybrid buncher is also described. Furthermore, the standard accelerating section can also be integrated with the hybrid buncher, this can further simplify the bunching system and lower the construction cost.

Slides TUODB101 [22.120 MB]

TUOAB202

ILSF, A Third Generation Light Source Laboratory in Iran

storage-ring, synchrotron, dipole, quadrupole

1137

J. Rahighi, M.R. Khabazi
IPM, Tehran, Iran
E. Ahmadi, H. Ajam, M. Akbari, S. Amiri, A. Babaei, J. Dehghani, R. Eghbali, J. Etemad Moghadam, S. Fatehi, M. Fereidani, H. Ghasem, A. Gholampour, A. Iraji, M. Jafarzadeh, B. Kamkari, S. Kashani, P. Khodadoost, H. Khosroabadi, M. Moradi, H. Oveisi, S. Pirani, M. Rahimi, M. Razazian, A. Sadeghipanah, F. Saeidi, R. Safian, E. Salimi, Kh.S. Sarhadi, O. Seify, M.Sh. Shafiee, A. Shahveh, A. Shahverdi, D. Shirangi, E.H. Yousefi
ILSF, Tehran, Iran
D. Einfeld
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

The Iranian Light Source Facility (ILSF) project is a first large scale accelerator facility which is currently under planning in Iran. The circumference of the storage ring is 297.6 m with the energy of 3 GeV. The facility will be built on a land of 100 hectares area in the city of Qazvin, located 150 km West of Tehran. The city is surrounded by many universities, research centers and industrial companies. The design and construction of prototype items such as radio frequency solid state amplifier, dipole magnets, highly stable magnet power supplies and girders have already begun. A low field H-type dipole magnet with the central field of 0.5T at the gap of 34mm and length of 500mm was built and tested in site. Also a prototype storage ring quadrupole with a 18 T/m gradient and 233 iron length is in now in fabrication process. Site selection studies, including geotechnical and seismological measurements are being performed. Conceptual Design Report, CDR, as the first milestone of the project has been published on October 2012.

Slides TUOAB202 [5.173 MB]

TUODB201

Recent Progress on the Development of a High Gradient RF System using High Impedance Magnetic Alloy, FT3L

impedance, acceleration, synchrotron, controls

1152

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

An upgrade project of J-PARC MR (Main Ring) includes developments of high gradient RF cavities and magnet power supplies for high repetition rate. A dedicated production system for high impedance magnetic alloy (FT3L) cores was assembled in J-PARC. This setup demonstrated that we can produce material with two times higher muQf product compared to the cores used for present cavities. And, the new results also show up to 20% higher impedance than the 2011 production with the former setup. In this summer, the system will be used for mass production of 200 FT3L cores for J-PARC MR. The cores produced in 2011 are already used for standard machine operation. The operation experience shows that the power loss in the cores was reduced significantly as expected. The scenario describing the upgrade plan of MR and the cavity replacements is reported. By the replacement plan, the total acceleration voltage will be almost doubled, while the number of RF stations remains the same.

Slides TUODB201 [5.105 MB]

TUODB202

Experiment and Numerical Simulation Results of Plasma Window

plasma, simulation, vacuum, cathode

1155

K. Zhu, S. Huang, Y.R. Lu, B.L. Shi
PKU, Beijing, People's Republic of China

Funding: Supported by NSFC 91026012
A windowless vacuum seal technique has been widely researched and designed, which can connect high pressure cavity to a vacuum condition with rather little thickness of material. As a result, it will reduce most interaction with the particle beam penetrating through comparing to that of foil window. It is desired extensively in experiments using high-intensity heavy ion beams which will break foil window in a short time or in experiments which require the injecting beams with mono-energy and high purity for example. In this work, we study the plasma window in argon which is used as a windowless vacuum sealing device. A numerical 2D FLUENT-based magneto-hydrodynamic model has been developed to investigate the physical reasons of high pressure difference in plasma window. Further, preliminary experimental results are presented and discussed.

Slides TUODB202 [2.180 MB]

TUPEA003

Components for CW and LP Operation of the XFEL Linac

cryomodule, linac, HOM, cathode

1164

J.K. Sekutowicz
DESY, Hamburg, Germany

The European XFEL will use superconducting TESLA cavities operating with 650 μs long bunch trains. With 220 ns bunch spacing and 10 Hz RF-pulse repetition rate, up to 27000 high quality bunches/s will be delivered to insertion devices generating unprecedented high average brilliance photon beams at very short wavelength. While many experiments can take advantage of full bunch trains, others prefer an increased intra-pulse distance of several μ-seconds between bunches, or short bursts with a kHz repetition rate. In this contribution, we discuss progress in the R&D program for a future upgrade of the European XFEL linac, to operation in the continuous wave (cw) and long pulse (lp) mode, which will allow for much more flexibility in the electron and photon beam time structure. Modifications and cw tests of XFEL cryomodules, recent tests result of the SRF injector, test of the second prototype of 120 kW IOT are presented. In addition, computer modeling of the cw-operating TESLA-like cavity with modified HOM couplers is briefly discussed.

TUPEA013

Present Status of Mid-infrared Free Electron Laser Facility in Kyoto University

FEL, gun, electron, undulator

1190

H. Zen, Y.W. Choi, H. Imon, M. Inukai, T. Kii, R. Kinjo, T. Konstantin, K. Masuda, K. Mishima, H. Negm, H. Ohgaki, K. Okumura, M. Omer, S. Shibata, K. Shimahashi, K. Yoshida
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

A Mid-Infrared Free Electron Laser (MIR-FEL) facility named as KU-FEL has been constructed for energy science in Institute of Advanced Energy, Kyoto University*. The accelerator of KU-FEL consists of an S-band 4.5-cell thermionic RF gun, a Dog-leg section for energy filtering, a 3-m traveling-wave type accelerator tube, 180-degree arc section for bunch compression and a hybrid undulator. We have already succeeded in lasing of the FEL from 5.5 to 14.5 micro-meter. Present status and recent activity for the FEL development will be presented in the conference.
*H. Zen, et al., Infrared Physics & Technology, vol.51, 382-385.

TUPEA030

High Brightness and Fully Coherent X-ray Pulses from XFELO Seeded High-gain FEL Schemes

FEL, radiation, electron, undulator

1214

H.X. Deng, C. Feng
SINAP, Shanghai, People's Republic of China

The successful operation of the hard x-ray self-seeding experiment at the LCLS opens the era of fully coherent hard x-ray free electron lasers (FELs). However, the shot-to-shot radiation fluctuation is still a serious issue. In this paper, high-gain, single-pass x-ray FEL schemes seeded by the narrow bandwidth radiation signal from an x-ray FEL oscillator were proposed and investigated, which are expected to generate high brightness, fully coherent and stable x-ray pulse. A simple model has been developed to figure out the temporal and the spectral structures of the output pulses in x-ray FEL oscillator. And options using two synchronized accelerators and using one accelerator were considered, respectively.

TUPEA043

Linac Design for Nuclear Data Measurement Facility

linac, neutron, electron, target

1229

M. Zhang, W. Fang, Q. Gu, X. Li
SINAP, Shanghai, People's Republic of China

Pulsed neutrons based on an electron linear accelerator (linac) are effective for measuring energy dependent cross-sections with high resolution by using the time-of-flight (TOF) technique. In this paper, we describe the 15-MeV linac design for the Nuclear Data project in Shanghai Institute of Applied Physics (SINAP). The linac has three operating modes and the maximum average power is 7.5kW. We describe the characteristics of the linac and the study of the beam dynamics is also presented.

TUPEA044

The Design of Control System for the Optical Cavity Adjuster of a FEL-THz Source

controls, FEL, electron, undulator

1232

X. Liu, Q. Fu, B. Qin, P. Tan, C. Wang, Y.Q. Xiong, J. Yang, H. Zeng
HUST, Wuhan, People's Republic of China

The optical cavity adjuster is an important sub-system in a FEL-THz source, which is used to adjust the position and angle of the optical cavity with a high precision. In view of the requirements of the optical cavity adjuster of the FEL-THz source, this paper presents the design of the control system of the optical cavity adjuster. The design of the control system based on a PC and a motion controller is adopted. The motion controller controls high-precision linear stage to adjust linear direction and picomotors are controlled to enable the adjustment of roll and yaw. According to relevant calculation, the range of linear direction and the accuracy can be reached at ±3mm and 0.2~0.5μm; the range of the adjustment of roll and yaw and the accuracy can be reached at ±2° and 20″. In summing up it can be stated that the design meets the requirements and it also lays the foundation for engineering on developing the optical cavity adjuster.

TUPEA068

Wake-field Reduction in Hybrid Photonic Crystal Accelerator Cavities

wakefield, lattice, dipole, simulation

1289

D. A. Rehn
Colorado University at Boulder, Boulder, Colorado, USA
C.A. Bauer, J.R. Cary, G.R. Werner
CIPS, Boulder, Colorado, USA
J.R. Cary, C.D. Zhou
Tech-X, Boulder, Colorado, USA

Funding: This work is supported by the U.S. Dept. of Energy, grant DE-FG02-04ER41317.
Photonic crystals (PhCs) have attractive properties for manipulating electromagnetic radiation. In one application, PhCs are composed of a number of dielectric rods that can be arranged to make an accelerator cavity. These structures trap an accelerating mode and allow higher order modes to propagate out. Previous work showed that PhC structures allow excitation of unwanted transverse wake-fields that can disrupt the beam and limit luminosity levels. This work focuses on optimizing PhC cavities to reduce transverse wake-fields by minimizing the Q-factor of unwanted modes, while keeping the Q-factor of the accelerating mode high. The transverse wake-fields in the new optimized structures are compared with previously optimized structures and the CLIC cavity with HOM damping.

TUPFI001

High Luminosity LHC Matching Section Layout vs Crab Cavity Voltage

optics, injection, luminosity, quadrupole

1328

B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
A. Chancé, J. Payet
CEA/DSM/IRFU, France
R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland

Funding: The research leading to these results has received funding from the European Commission under the FP7 project HiLumi LHC, GA no. 284404, co-funded by the DoE, USA and KEK, Japan.
In the framework of the HL-LHC Upgrade project we present a new possible variant for the layout of the LHC matching section located in the high luminosity insertions. This layout is optimized to reduce the demand on the voltage of the crab cavities, while substantially improving the optics squeeze-ability, both in ATS [1] and non-ATS mode. These new layout will be described in details together with its performance figures in terms of mechanical acceptance, chromatic properties and optics flexibility. [1] S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI023

Optics Design and Lattice Optimisation for the HL-LHC

optics, luminosity, quadrupole, lattice

1385

B.J. Holzer, R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland
R. Appleby, S. Kelly, M.B. Thomas, L.N.S. Thompson
UMAN, Manchester, United Kingdom
A.V. Bogomyagkov
BINP SB RAS, Novosibirsk, Russia
A. Chancé
CEA, Gif-sur-Yvette, France
B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
A. Faus-Golfe, J. Resta
IFIC, Valencia, Spain
K.M. Hock, M. Korostelev, L.N.S. Thompson, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C. Milardi
INFN/LNF, Frascati (Roma), Italy
J. Payet
CEA/DSM/IRFU, France
A. Wolski
The University of Liverpool, Liverpool, United Kingdom

Funding: The HiLumi LHC Design Study is included in the High Luminosity LHC project and is partly funded by the European Commission within the Framework Programme 7 Cap. Spec. Progr, Grant Agreement 284404.
The luminosity upgrade project of the LHC collider at CERN is based on a strong focusing scheme to reach smallest beam sizes at the collision points. Depending on the available magnet technology (Nb3Sn or NbTi) a number of beam optics has been developed to define the specifications for the new super conducting quadrupoles. In the context of the optics matching new issues have been addressed and new concepts have been used: Quadrupole strength flexibility and chromatic corrections have been studied, as well as the influence of quadrupole fringe fields. The lattice has been optimised including the needs of the foreseen crab cavities and the transition between injection and low β optics had to guarantee smooth gradient changes over a wide range of β* values. Tolerances on misalignments and power converter ripple have been re-evaluated. Finally the combination of the quadrupole strengths in the high luminosity matching sections with those in the neighboring sectors is explained, a key concept of the ATS to reach smallest β* values. This paper presents the results obtained within the HiLumi collaboration Task 2.2 and summarises the main parameters of the project.

TUPFI053

Transient Beam Loading Effects in Gas-filled RF Cavities for a Muon Collider

plasma, ion, beam-loading, electron

1463

M. Chung, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, USA
B.T. Freemire
IIT, Chicago, Illinois, USA

Funding: Research supported by the U.S. Department of Energy.
A gas-filled RF cavity can be an effective solution for the development of a compact muon ionization cooling channel. One possible problem expected in this type of cavity is the dissipation of significant RF power through the beam-induced plasmas accumulated inside the cavity (plasma loading). In addition, for the higher muon beam intensity, the effects of the beam itself on the cavity fields in the accelerating mode are non-negligible (beam loading). These beam-cavity interactions induce a transient phase which may be very harmful to the beam quality. In this study, we estimate the transient voltage in a gas-filled RF cavity with both the plasma and conventional beam loading and discuss their compensation methods.

TUPFI064

Beam Induced Plasma Dynamics in a High Pressure Gas-Filled RF Test Cell for use in a Muon Cooling Channel

electron, ion, plasma, proton

1496

B.T. Freemire, P.M. Hanlet, Y. Torun
IIT, Chicago, Illinois, USA
M. Chung, M.R. Jana, M.A. Leonova, A. Moretti, T.A. Schwarz, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, USA
M.G. Collura
Politecnico di Torino, Torino, Italy
R.P. Johnson
Muons. Inc., USA

Filling an RF cavity with a high pressure gas prevents breakdown when the cavity is place in a multi-Tesla external magnetic field. The choice of hydrogen gas provides the additional benefit of cooling a beam of muons. A beam of particles traversing the cavity, be it muons or protons, ionizes the gas, creating an electron-ion plasma which absorbs energy from the cavity. The ionization rate can be calculated from a beam intensity measurement. Energy loss measurements indicate the loading per RF cycle per electron-ion pair range from 10^-18 to 10^-16 Joules in pure hydrogen, and 10^-20 to 10^-18 Joules when hydrogen is doped with dry air. The addition of an electronegative gas (oxygen) has been observed to reduce the lifetime of ionization electrons in the cavity to below 1 nanosecond. Additionally, the recombination rate of electrons and hydrogen ions has been measured to be on the order of 10^-6 cubic centimeters per second. The recombination mechanism and hydrogen ion species, along with the three-body attachment process of electrons to oxygen, will be discussed.

TUPFI065

Muon Ionization Cooling Experiment Step VI

coupling, emittance, vacuum, status

1499

D. Rajaram
Illinois Institute of Technology, Chicago, Illinois, USA
P. Snopok
IIT, Chicago, Illinois, USA

The Muon Ionization Cooling Experiment (MICE) is a demonstration experiment to prove the viability of cooling a beam of muons for use in a Neutrino Factory and Muon Collider. The ultimate Step VI configuration of the MICE cooling channel, a section of the one proposed in the Neutrino Factory Study II, will demonstrate a 10% reduction in transverse beam emittance measured at the level of 1%. This requires measuring emittance to 0.1%. This measurement will be made using all beam line elements present in the MICE Step IV configuration with the addition of two low-Z absorber modules and two RF-Coupling Coil (RFCC) modules. The RFCC modules each contain four normal-conducting low frequency (201 MHz) RF cavities with a guiding magnetic field provided by a large diameter coupling coil. Each of these cavities will require approximately 1 MW of RF power in a 1 ms pulse at a rate of 1 Hz. The experiment can explore a variety of combinations of momentum, beta function, magnetic field flip or non-flip configurations that will prove precious in the design of future cooling channels. The current status and progress toward Step VI are discussed.

TUPFI068

High Power Tests of Alumina in High Pressure RF Cavities for Muon Ionization Cooling Channel

pick-up, collider, resonance, klystron

1508

L.M. Nash
University of Chicago, Chicago, Illinois, USA
G. Flanagan, R.P. Johnson, F. Marhauser, J.H. Nipper
Muons. Inc., USA
M.A. Leonova, A. Moretti, M. Popovic, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, USA
Y. Torun
IIT, Chicago, Illinois, USA

It is important to make a compact muon ionization cooling channel to increase the cooling efficiency (muon survival rate, cooling decrement, etc). A proposed scheme to reduce the radial size of RF cavities at a given resonance frequency is to insert a dielectric material into the RF cavity. In vacuum cavities, however, dielectric materials are extremely susceptible to breakdown in high power conditions. High-pressure hydrogen gas has been shown to inhibit breakdown events in RF cavities in strong magnetic fields. An experiment has been designed to test surface breakdown of alumina in RF cavities. A structure has been designed to maximize the parallel field parallel to the surface while bringing the cavity into a desired frequency range (800-810MHz). Alumina is tested in this configuration under high power conditions. The experimental result will be shown in this presentation.

TUPFI081

Progress with Coherent Electron Cooling Proof-Of-Principle Experiment

electron, gun, ion, undulator

1535

I. Pinayev, S.A. Belomestnykh, I. Ben-Zvi, K.A. Brown, J.C. Brutus, L. DeSanto, A. Elizarov, C. Folz, D.M. Gassner, Y. Hao, R.L. Hulsart, Y.C. Jing, D. Kayran, R.F. Lambiase, V. Litvinenko, G.J. Mahler, M. Mapes, W. Meng, R.J. Michnoff, T.A. Miller, M.G. Minty, P. Orfin, A. Pendzick, F. Randazzo, T. Rao, T. Roser, J. Sandberg, B. Sheehy, J. Skaritka, K.S. Smith, L. Snydstrup, R. Than, R.J. Todd, J.E. Tuozzolo, G. Wang, D. Weiss, M. Wilinski, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA
G.I. Bell, J.R. Cary, K. Paul, B.T. Schwartz, S.D. Webb
Tech-X, Boulder, Colorado, USA
C.H. Boulware, T.L. Grimm, R. Jecks, N. Miller
Niowave, Inc., Lansing, Michigan, USA
M.A. Kholopov, P. Vobly
BINP SB RAS, Novosibirsk, Russia
M. Poelker
JLAB, Newport News, Virginia, USA

We conduct proof-of-the-principle experiment of coherent electron cooling (CEC), which has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. In this paper, we present the progress with experimental equipment including the first tests of the electron gun and the magnetic measurements of the wiggler prototype. We describe current design status as well as near future plans.

TUPFI087

Alternative Muon Cooling Options based on Particle-Matter-Interaction for a Neutrino Factory

lattice, focusing, solenoid, proton

1550

D. Stratakis
BNL, Upton, Long Island, New York, USA
A. Alekou
CERN, Geneva, Switzerland
D.V. Neuffer, P. Snopok
Fermilab, Batavia, USA
J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
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
P. Snopok
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: This work is funded by US Dept. of Energy grant numbers DE AC02-98CH10886
An ionization cooling channel is a tightly spaced lattice containing absorbers for reducing the momentum of the muon beam, rf cavities for restoring the momentum and strong solenoids for focusing the beam. Such a lattice is an essential feature of most designs for Neutrino Factories and Muon Colliders. Here, we explore three different approaches for designing ionization cooling channels with periodic solenoidal focusing. Key parameters such as the engineering constraints that are arising from the length and separation between the solenoidal coils are systematically examined. In addition, we propose novel approaches for reducing the peak magnetic field inside the rf cavities by using either a magnetic shield system or a bucked coils configuration. Our lattice designs are numerically examined against two independent codes: The ICOOL and G4BL code. The feasibility of our proposed cooling channels to muon accelerators is examined by applying the proposed lattices to the front-end of a Neutrino Factory.

TUPME015

Proposal of Polarized Gamma-ray Source for ILC Based on CSR Inverse Compton Scattering

electron, positron, scattering, laser

1598

M. Shimada, K. Yokoya
KEK, Ibaraki, Japan
R. Hajima
JAEA, Ibaraki-ken, Japan
M. Tecimer
University of Hawaii at Manoa, Honolulu, USA

The positron source of International Linear Collider (ILC) requires a circular polarized gamma-ray with a flux more than 10¹⁶ phs./s and a helical undulator-based gamma-ray source is proposed in the baseline design. Although the undulator scheme is technically feasible, it is not easy for a stand-alone operation because of the required electron energy, ~ 150GeV. In this paper, we propose an alternative method, the inverse Compton scattering with a high-power mid-infrared optical pulse generated from coherent synchrotron radiation (CSR). To achieve the high flux gamma-ray, CSR with a few MHz is stacked in a high-finesse optical cavity made of a photonic crystal. In the proposed scheme, a stand-alone operation is feasible because the electron energy is less than 10GeV.

TUPME026

Optimization on RF parameters of a Choke-Mode Structure for the Clic Main LINAC

wakefield, simulation, linac, accelerating-gradient

1628

H. Zha, H.B. Chen, J. Shi
TUB, Beijing, People's Republic of China

Funding: This work was support by the National Natural Science Foundation of China (Grant No. 11135004).
A tapered choke-mode structure for the main linac of Compact Linear Collider (CLIC) had been designed. Wakefield suppression of this structure fits the beam dynamic requirements. But it has a lower RF performance compared to the baseline design of CLIC main linac. A genetic algorithm is used in the procedure to find the optimum solution. A new choke-mode structure with 24 regular cells working on 100MV/m has been design, which fits beam dynamic constraints and has higher RF efficiency and lower surface field.

TUPME065

Experimental Study of Horizontal-Longitudinal Coupling at CesrTA

coupling, lattice, simulation, scattering

1715

M. P. Ehrlichman, A. Chatterjee, W. Hartung, D.P. Peterson, N.T. Rider, D. L. Rubin, J.P. Shanks, S. Wang
CLASSE, Ithaca, New York, USA

Funding: This research was supported by NSF and DOE contracts PHY-0734867, PHY-1002467, PHYS-1068662, DE-FC02-08ER41538, DE-SC0006505.
In storage rings, the presence of horizontal dispersion in the RF cavities introduces x-z coupling. The result is that the beam is skewed in the horizontal-longitudinal plane. The skew angle is proportional to the V15 term of the 6X6 coupling matrix which is proportional to the RF cavity voltage and the horizontal dispersion in the cavity. Here we report experiments at CesrTA where x-z coupling was explored using three distinct lattice configurations with different V15 coupling terms. We explore x-z coupling for each of these lattices by measuring the horizontal projection of the beam with a beam size monitor, as the RF voltage is varied. The first lattice has about 1 m dispersion in the RF cavities, resulting in a V15 term at the beam size monitor source point corresponding to 16 mrad x-z tilt. In the second, the V15 generated in one pair of cavities is compensated at the second pair by adjusting the horizontal betatron phase advance between the cavity pairs. In the third, the optics are adjusted so that the RF cavity region is dispersion-free, eliminating the coupling entirely. Additionally, intra-beam scattering is evident in our measurements of beam size vs. RF voltage.

TUPWA018

Local Compensation-Rematch for Element Failures in the Low Energy Section of C-Ads Accelerator

solenoid, emittance, linac, focusing

1760

B. Sun, Z. Li, J.Y. Tang, F. Yan
IHEP, Beijing, People's Republic of China

Due to the requirement of high reliability and availability for the C-ADS accelerators, a fault tolerance design is pursued. The effects of transverse focusing element failures in different locations have been studied and the schemes of compensation by means of local compensation have been investigated. After one transverse element failure especially in the low energy section happens, some new methods have been purposed by which the new settings of the neighbouring solenoids and the cavities can be set, and the Twiss parameters and energy can be approximately recovered to that of the nominal ones at the matching point. We find that the normalized RMS emittance in transverse and longitudinal planes have no obvious growth after applying the compensation in each section of the main linac. When we make study on the compensation-rematch for the RF cavity failures, the TraceWin code has been used that doesn’t consider the phase change during the cavity resetting, so a code named LOCCOM, which is based on MATLAB, is developed and used to compensate the error on arrival-time at the matching point.

TUPWA021

Multi-Pass, Multi-Bunch Beam Breakup of ERLs with 9-cell Tesla Cavities

HOM, betatron, dipole, simulation

1769

S. Chen, J.E. Chen, L.W. Feng, S. Huang, Y.M. Li, K.X. Liu, S.W. Quan, F. Zhu
PKU, Beijing, People's Republic of China

Funding: Supported by the Major State Basic Research Development Program of China under Grant No. 2011CB808303 and No. 2011CB808304
In this paper, multi-pass, multi-bunch beam break-up of some small-scale Energy Recovery Linac(ERL) configuration using 9-cell Tesla cavity is discussed. The threshold currents of different cases are investigated and some factors that influence the threshold currents are discussed.

TUPWA022

Beam Dynamics Design of a 325 MHz RFQ

rfq, emittance, proton, simulation

1772

F.J. Jia, J.E. Chen, G. Liu, Y.R. Lu, X.Q. Yan
PKU, Beijing, People's Republic of China
B.Q. Cui, J.H. Li, G.H. Wei
CIAE, Beijing, People's Republic of China

The beam dynamic design of a 325 MHz Radio Frequency Quadrupole (RFQ) is presented in this paper. This 4-vane RFQ will accelerate pulsed proton beam from 30 keV to 3 MeV with repetition frequency of 1 MHz. A 1 MHz chopper and a 5 MHz buncher are arranged in the Low-Energy-Beam-Transport (LEBT) to produce the injected beam. The beam length at the RFQ entrance is about 3 ns, and the energy-spread is about 10%. The code of PARMTEQM is used to simulate RFQ structure. The design should realize high transmission for very high intensity beam meanwhile low emittance growth and relatively short length should be kept.

TUPWA023

Design of the Tuning System for the He⁺ Coupled RFQ-SFRFQ Cavity

rfq, simulation, linac, impedance

1775

W.L. Xia, J.E. Chen, S.L. Gao, Z.Y. Guo, Y.R. Lu, S.X. Peng, Z. Wang, X.Q. Yan, J. Zhao, K. Zhu
PKU, Beijing, People's Republic of China

Funding: Supported by NSFC 10905003, 11079001, 91026012 Corresponding author: wangzhi@pku.edu.cn
The CRS (coupled RFQ-SFRFQ) cavity is a new type linac that couples traditional RFQ (radio frequency quadrupole) and SFRFQ (separated function RFQ) electrodes into a single cavity. The overall design of the CRS cavity has been completed and the linac is being manufactured currently. In this paper, we aimed to design a frequency tuning system for the CRS cavity, which will be used to explore the electromagnetic field distribution between RFQ and SFRFQ sections in the cavity. The frequency range, variation of Q value, power consumption and electric field distribution were investigated. Based on the beam dynamic program SFRFQDYNv1.0, we analysed the beam transmission properties of the cavity under the unbalanced electric field distribution. The optimized parameters of the tuning system were obtained.

TUPWA038

Equilibrium Bunch Density Distribution with Passive Harmonic Cavities in the MAX IV 3 GeV Storage Ring

impedance, storage-ring, emittance, damping

1790

P.F. Tavares, Å. Andersson, A. Hansson
MAX-lab, Lund, Sweden

The MAX IV storage rings will use third harmonic cavities operated passively to lengthen the bunches and alleviate collective instabilities. These cavities are an essential ingredient in the MAX IV design concept and are required for achieving the final design goals in terms of stored current, beam emittance and beam lifetime. This paper reports on fully self-consistent calculations of the longitudinal bunch density distribution in the MAX IV 3 GeV storage ring, which indicate that up to a factor 5 increase in RMS bunch length is achievable with a purely passive system.

TUPWA044

Longitudinal Coupled-Bunch Oscillation Studies in the CERN PS

damping, feedback, kicker, emittance

1808

H. Damerau, S. Hancock, M.M. Paoluzzi
CERN, Geneva, Switzerland
M. Migliorati, L. Ventura
Rome University La Sapienza, Roma, Italy

Longitudinal coupled-bunch oscillations are an important limitation for the high-brightness beams accelerated in the CERN PS. Up to the present intensities they are suppressed by a dedicated feedback system limited to the two dominant oscillation modes. In view of the proposed installation of a wide-band feedback kicker cavity within the framework of the LHC Injectors Upgrade project (LIU), measurements have been performed with the existing damping system with the aim of dimensioning the new one. Following the excitation of well-defined oscillation modes, damping times and corresponding longitudinal kick strength are analysed. The paper summarizes the results of the observations and gives an outlook on the expected performance with the new coupled-bunch feedback.

TUPWO005

Survey of Beam Optics Solutions for the MLS Lattice

optics, emittance, quadrupole, lattice

1883

M. Ries, J. Feikes, T. Goetsch, G. Wüstefeld
HZB, Berlin, Germany

The Metrology Light Source (MLS) is an electron storage ring containing 24 quadrupole magnets which can be powered individually. Fully exploring the capabilities of the machine optics by tracking or experiment would be very time consuming. Therefore the quadrupoles were combined in five families and a numerical brute force approach was used to scan for areas of stable solutions in the scope of linear beam optics. In order to get information on the expected beam lifetimes for each generated optics, a model for the Touschek lifetime was implemented. Simulation results as well as experimental tests of selected optics will be presented.

TUPWO016

Beam Dynamics Design of 3 MeV Medium Energy Beam Transport for Beam Intensity Upgrade of J-PARC Linac

emittance, DTL, simulation, linac

1916

T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

The J-PARC linac has a plan to upgrade its beam power in the summer 2013. This plan includes the replacement of the front-end components (ion source and 3 MeV RFQ) to increase the peak current from present 30 mA to 50 mA. Since it results in the different injection beam profile to medium energy beam transport (MEBT), which locates the RFQ downstream, we designed the beam dynamics of MEBT. In this presentation, we disscuss the new design of beam dynamics in MEBT.

TUPWO019

A Local Achromatic Design of C-ADS MEBT2

emittance, linac, bunching, controls

1922

H. Geng, Z. Guo, Z. Li, C. Meng, S. Pei, J.Y. Tang
IHEP, Beijing, People's Republic of China

The accelerator of China Accelerator Driven Sub-critical system consists of two injectors to ensure its high reliability. The Medium Energy Beam Transport line-2 is an essential part of the accelerator to transport and match the beam from either injector to the main linac. This paper presents a local achromatic design, which uses four bending magnets, for CADS MEBT2. It is found that both transverse and longitudinal emittance growths can be well controlled below 15% from MEBT2 entrance to the exit of the following superconducting spoke-021 section. The beam dynamics of MEBT2 will be discussed and the multi-particle tracking results will also be shown.

TUPWO020

Error Analysis for C-ADS MEBT2

emittance, linac, beam-transport, solenoid

1925

H. Geng, Z. Guo, Z. Li, C. Meng, S. Pei, J.Y. Tang
IHEP, Beijing, People's Republic of China

A local achromatic scheme has been developed for C-ADS MEBT2. This paper presents the error analysis results for this MEBT2 scheme. The effects of magnet and cavity misalignment, static and dynamic errors of electric and magnetic field, the displacement of the input beam as well as the initial mismatches of the incoming beam will be studied. Beam trajectory correction scheme will also be discussed.

TUPWO029

Beam Line Design at the CAEP THz Free Electron Laser

electron, emittance, laser, FEL

1937

P. Li, W. Bai, H. Wang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China
X. Li
TUB, Beijing, People's Republic of China

China Academy of Physics (CAEP) is currently building a THz Free Electron Laser (THz-FEL) which serves as a radiation light sourse used for research in a variety of experimental fields. In this paper, we present the design of the beam line, which was accomplished using PARMELA and TRANSPORT code simulations. The accelerator consists of a 350 kV photocathode DC gun in conjunction with one cryomodule containing two 4-cell superconductiong RF cavities. The energy of the elctron beam is 7~8 MeV, and the maximum of the average beam current is 5 mA. A transverse emittance typically below 10 pi mm.mrad can be achieved.

TUPWO046

The ESS Linac Simulator: A First Benchmark with TraceWin

space-charge, linac, simulation, multipole

1970

E. Laface, M. Eshraqi, R. Miyamoto
ESS, Lund, Sweden

The ESS Linac Simulator, ELS, will be the core of the online model used in the normal operations of the ESS linac. ESS Linac Simulator will operate through the eXtensible Accelerator Language, XAL, in order to provide an effective interface capable to simulate and predict the beam dynamics of the accelerator. The ELS is capable of simulating the dynamics of the beam envelope in both transverse and longitudinal planes in real time. In order to validate the effectiveness of the physics implemented, the ELS calculations are here benchmarked with TraceWin: the simulation code used for the design of the accelerator.

WEOAB101

Single Particle Tracking for Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring

HOM, simulation, synchrotron, optics

2038

M. Ruprecht, A. Jankowiak, A. Neumann, M. Ries, G. Wüstefeld
HZB, Berlin, Germany
T. Weis
DELTA, Dortmund, Germany

A scheme where 1.5 ps and 15 ps long bunches (rms) can be stored simultaneously in the BESSY II storage ring has recently been proposed (BESSY^VSR*). This paper presents simulations of single particle beam dynamics influenced by superconducting cavities used for the strong longitudinal beam focusing. The effect of RF jitter on (very short) bunches is investigated and results are discussed. Furthermore, possible effects on beam dynamics during ramp up and ramp down of the high gradient fields in the cavities are studied. The primary goal is to reveal preliminary design specifications for RF jitter on the basis of single particle dynamics.
* G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries, Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring, Proceedings of IPAC2011, San Sebastián, Spain

Slides WEOAB101 [3.955 MB]

WEYB101

Power Upgrade of J-PARC Linac

rfq, ion, linac, ion-source

2047

H. Oguri
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

A linac power upgrade program is now in progress after a successful recovery from the earthquake disaster. The power upgrade includes an ion source, an RFQ and a 400 MeV Annular-ring Coupled Structure (ACS) linac. We started a full-scale development of a cesium seeded RF-driven negative hydrogen ion source. The ion source extracted the beam of more than 60 mA with a duty factor of 2.5 %, which is satisfied with the requirement of the program. A new RFQ for 50 mA acceleration is under construction on the basis of a RFQ fabrication process, which was built as a backup for the present RFQ. Mass production of the ACS modules have almost completed. There is a plan to install these components and schedule the beam test in 2013. This presentation will cover the power upgrade status of the J-PARC linac.

Slides WEYB101 [4.205 MB]

WEIB202

Industrialization of the ILC Project

SRF, linac, linear-collider, collider

2105

M.C. Ross
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
The International Linear Collider Global Design Effort (GDE) team completed the Technical Design Report (TDR) in early 2013. The TDR consists of a description of the machine design, a summary of the R&D program carried out in support of the design, a cost estimate and a project plan. The number of high technology components to be fabricated for ILC is large, similar to that built for the Large Hadron Collider*, and industrial partners have had an important role throughout the technical development and design period. It is recognized that transfer of new technology to industrial partners and subsequent collaborative development can be difficult**. To counter this, the ILC Technical Design Phase (TDP) team arranged a series of vendor visits, component development contracts, workshop satellite meetings and industrial production study contracts. The GDE collaboration provided the framework for development through an agreed-upon performance parameter set and project implementation scheme. The latter includes a ‘plug-compatibility’ policy that promotes innovation as long as specified interface conditions are met. In this paper we show the evolution of the technology from the labs where it was developed to the companies where high performance cavities are now routinely produced.
* The longest journey: the LHC dipoles arrive on time.
http://cerncourier.com/cws/article/cern/29723
** Office of High Energy Physics Accelerator R&D Task Force Report
http://www.acceleratorsamerica.org/report/accelerator_task_force_report.pdf

Slides WEIB202 [5.181 MB]

WEIB203

Industrialization of ILC from a View Point of Industry

HOM, target, vacuum, status

2110

K. Sennyu, H. Hara, F. Inoue, K. Kanaoka, K. Okihira
MHI, Hiroshima, Japan

Cavity performance has been improved by various efforts to meet the ILC spec stably in these days. For industrialization, not only Quality but also Cost and Delivery time, that is, QCD are important. We report our activities for stable quality and cost reduction in this report.

Slides WEIB203 [5.789 MB]

WEPWA009

RF Bunch Compression Studies for FLUTE

linac, simulation, gun, space-charge

2144

M. Schuh, E. Huttel, S. Marsching, A.-S. Müller, S. Naknaimueang, M.J. Nasse, R. Rossmanith, R. Ruprecht, M. Schreck, M. Schwarz, M. Weber, P. Wesolowski
KIT, Karlsruhe, Germany
R.W. Aßmann, K. Flöttmann, H. Schlarb
DESY, Hamburg, Germany

FLUTE is a planned 40 to 50 MeV accelerator test facility consisting, in the first phase, of an electron gun with an output energy of about 7 MeV, a traveling wave linac and a magnet chicane bunch compressor. The machine will serve as a source of intense THz radiation using coherent synchrotron radiation (CSR), coherent transition radiation (CTR), and coherent edge radiation (CER) as generation mechanisms. It is planned to operate the machine in the charge regime from a few pC up to several nC in order to study bunch compression schemes as well as the THz radiation generation. In this contribution the effect of velocity bunching by using a dedicated buncher cavity at low energy and operating the linac off-crest is studied in order to deliver RMS bunch lengths in the femtosecond range at low charge.

WEPWA017

Development of Laser-Compton X-ray Source using Optical Storage Cavity

laser, electron, booster, linac

2165

K. Sakaue, M. Washio
Waseda University, Tokyo, Japan
M.K. Fukuda, Y. Honda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Funding: Work supported by the Quantum Beam Technology Program of MEXT and JSPS Grant-in-Aid for Young Scientists (B) 23740203
We have been developing a pulsed-laser storage technique in a super-cavity for a compact x-ray sources. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. We already obtained a pulse-train x-rays through the laser-Compton scattering between a multi-bunch electron beam and an optical super-cavity. And also, we performed a X-ray imaging via laser-Compton X-ray. On these successful results, we decided to upgrade our system for increasing X-ray flux by 3-order of magnitudes for practical use. For an optical cavity, we designed 4-mirrors bow-tie cavity in order to increase the power. On the other hand, electron accelerator was also upgraded to increase the bunch number in the train. We use 3.6cells rf-gun and 12cell standing wave booster linac. As a result, 2-order increase of X-ray flux was achieved. Design of upgraded our laser-Compton X-ray source, the results of X-ray experiments and future prospective will be presented at the conference.

WEPWA020

Laser Electron Storage Ring for TTX

laser, electron, storage-ring, quadrupole

2171

H.S. Xu, W.-H. Huang, C.-X. Tang, L.X. Yan, Y. You
TUB, Beijing, People's Republic of China
D. Jehanno, Z.F. Zomer
LAL, Orsay, France
S.-Y. Lee
IUCEEM, Bloomington, Indiana, USA

Tsinghua Thomson scattering X-ray (TTX) source, proposed by Tsinghua University, is a hard x-ray source with multi-application in condensed matter physics, etc. The TTX is composed of an S-band photocathode RF gun and a SLAC type 3m travelling wave Linac, and a femto-second tera-watt laser system drives the photocathode. The TTX source is in operation. To extend the capability of TTX, we plan to design a ring based system to increase the photon flux. In this paper, we report the design of the compact electron storage ring and optical cavity, expected performance, and future prospects.

WEPWA037

Effect of Ground Vibration on the Out-coupled Power in a Terahertz FEL Oscillator

FEL, simulation, alignment, laser

2211

Q. Fu, L.Z. Deng, B. Qin, P. Tan, Y.Q. Xiong, Y.B. Yibin, H. Zeng
HUST, Wuhan, People's Republic of China

To acquire high power out-coupled, we must ensure the co-axis of electron orbit, optical beam and magnetic field. The propagation of ground vibration through the optical platform will lead to misalignment of the optical axis in the FEL optical cavity. Based on measurement results of the ground vibration, simulations of misalignment are studied with GENESIS+OPC. The tolerance of mirror tilt and offset is also discussed.

WEPWA047

Longitudinal Stability of Multiturn ERL with Split Accelerating Structure

linac, electron, simulation, resonance

2226

Ya.V. Getmanov, O.A. Shevchenko, N. Vinokurov
BINP SB RAS, Novosibirsk, Russia
T. Atkinson
HZB, Berlin, Germany
N. Vinokurov
KAERI, Daejon, Republic of Korea

Some modern projects of the new generation light sources use the conception of multipass energy recovery linac with split (CEBAF-like) accelerating structures. One of the advantages of these light sources is the possibility to obtain a small longitudinal beam size. To help reduce it, the longitudinal dispersion should be non-zero in some arcs of the accelerator. However small deviations in voltages of the accelerating structures can be enhanced by induced fields from circulating bunches due to the dependence of the flight time on the energy spread and the high quality factor of the superconducting radio-frequency cavities. Therefore, instabilities related with interactions of the electron bunches and longitudinal modes of the cavities can develop in the installation. Stability conditions for the interactions with fundamental accelerating mode of the split accelerating system are discussed. Numerical simulations are made for two projects - MARS and FSF.

WEPWA058

Operation of the NSRRC 2998 MHz Photo-cathode RF Gun

gun, laser, electron, cathode

2247

A.P. Lee, M.C. Chou, J.-Y. Hwang, W.K. Lau
NSRRC, Hsinchu, Taiwan
P. Chiu, N.Y. Huang, P. Wang
NTHU, Hsinchu, Taiwan

We are developing the photoinjector technology for single pass high gain FEL research at NSRRC. A gun test facility(GTF) equipped with a 35 MW, S-band high power pulsed klystron as well as a 300 uJ, UV driver laser has been constructed for testing photo-cathode rf guns. Recently, a 2998 MHz, 1.6-cell photo-cathode rf gun has been fabricated in house and is being tested at the NSRRC GTF. Details of this setup will be described and the operational performance of this electron gun will be reported.

WEPWA068

Design Concepts for the NGLS Linac

linac, cryomodule, cryogenics, HOM

2271

A. Ratti, J.M. Byrd, J.N. Corlett, L.R. Doolittle, P. Emma, J. Qiang, M. Venturini, R.P. Wells
LBNL, Berkeley, California, USA
C. Adolphsen, C.D. Nantista
SLAC, Menlo Park, California, USA
D. Arenius, S.V. Benson, D. Douglas, A. Hutton, G. Neil, W. Oren, G.P. Williams
JLAB, Newport News, Virginia, USA
C.M. Ginsburg, R.D. Kephart, T.J. Peterson, A.I. Sukhanov
Fermilab, Batavia, USA

The Next Generation Light Source (NGLS) is a design concept for a multibeamline soft x-ray FEL array powered by a ~2.4 GeV CW superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. This paper describes the concepts under development for a linac operating at 1.3 GHZ and based on minimal modifications to the design of ILC cryomodules in order to leverage the extensive R&D that resulted in the ILC design. Due to the different nature of the two applications, particular attention is given here to high loaded Q operation andμphonics control, as well as high reliability and expected up time.

WEPWA069

Design Concepts for an RF Deflecting Cavity-Based Beam Spreader for a Next Generation FEL

dipole, FEL, gun, septum

2274

M. Placidi, L.R. Doolittle, P. Emma, J.-Y. Jung, J. Qiang, A. Ratti, C. Sun
LBNL, Berkeley, California, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
The Lawrence Berkeley National Laboratory (LBNL) is developing design concepts for a multi-beamline soft x-ray FEL array powered by a superconducting linear accelerator, operating with a high bunch repetition rate of approximately one MHz. Electron bunches supplied by a high-brightness, high-repetition-rate photocathode electron gun are distributed by a beam spreader, designed to deliver individual bunches from a CW linac to an array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. We describe recent developments in the technical choices, design and parameters of the spreader system and its main components.

WEPWA078

Compact Accelerator Design for a Compton Light Source

electron, gun, emittance, photon

2292

T. Satogata, K.E. Deitrick, J.R. Delayen, B.R.P. Gamage, K.G. Hernández-Chahín, C.S. Hopper, G.A. Krafft, R.G. Olave
ODU, Norfolk, Virginia, USA
K.G. Hernández-Chahín
DCI-UG, León, Mexico
G.A. Krafft, T. Satogata
JLAB, Newport News, Virginia, USA

Funding: Partially authored by Jefferson Science Associates, LLC under U.S. DOE contract NO. DE-AC05-06OR23177.
A compact electron accelerator suitable for Compton source applications is in design at the Center for Accelerator Science at Old Dominion University and Jefferson Lab. The design includes a KE=1.55 MeV low-emittance, optimized superconducting electron gun; a 23.45 MeV linac with multi-spoke 4.2 K superconducting cavities; and transport that combines magnetic longitudinal bunch compressor and transverse final focus. We report on the initial designs of each element, including end to end simulations with ASTRA and elegant, and expected beam parameters.

WEPWO002

RF Measurements of the 1.6 Cell Lead/Niobium Photoinjector in HoBiCaT

gun, cathode, vacuum, SRF

2313

A. Burrill, W. Anders, T. Kamps, J. Knobloch, O. Kugeler, P. Lauinger, A. Neumann
HZB, Berlin, Germany
P. Kneisel
JLAB, Newport News, Virginia, USA
R. Nietubyć
NCBJ, Świerk/Otwock, Poland
J.K. Sekutowicz
DESY, Hamburg, Germany

The development of a simple and robust SRF photoinjector capable of delivering up to 1 mA average current in c.w. operation continues to progress with the horizontal RF testing of the 1.6 cell Pb/Nb hybrid photoinjector. This injector utilizes a sputtered lead coating on a removable Nb cathode plug as the photoelectron source and has recently been tested in the horizontal test cryostat facility, HoBiCaT, at HZB. In this paper we will report on the status of these RF measurements and compare the performance to previous vertical RF tests performed at JLab. We will also report on the experience operating this cavity with a TTF-III high power RF input coupler, as well as provide a summary of the microphonics susceptibility now that it has been installed into a helium vessel and equipped with a Saclay style tuner.

WEPWO004

Studies of Systematic Flux Expulsion in Superconducting Niobium

niobium, simulation, lattice, controls

2316

J.M. Vogt, J. Knobloch, O. Kugeler
HZB, Berlin, Germany

The quality factor Q0 that can be obtained in a superconducting cavity is known to depend on various factors like niobium material properties, treatment history and magnetic shielding. We believe that cooling conditions have an additional impact, as they appear to influence the amount of trapped flux and hence the residual resistance. We have constructed a test stand using niobium rods to study flux trapping. Here we can precisely control the temperature and approach Tc from below in the superconducting state. Although the sample remains in the superconducting state, a change in the amount of trapped flux is visible. The procedure can be applied repeatedly resulting in a significantly lowered level of trapped flux in the sample. Furthermore, simulations using the Radia software package for Mathematica developed by the ESR were used to better unterstand the measured changes in magnetic flux around the Sample. Applying a similar procedure for minimization of trapped magnetic flux to a superconducting cavity could allow for reduction of the magnetic contribution to the surface resistance and result in a significant improvement of Q0.

WEPWO005

Microphonics Analysis of the SC 325 MHz CH-Cavity

simulation, resonance, vacuum, status

2319

M. Amberg, M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Amberg, K. Aulenbacher
HIM, Mainz, Germany
K. Aulenbacher
IKP, Mainz, Germany

Since the walls of superconducting (sc) cavities are kept very thin to support the cooling process, even small mechanical disturbances can detune the cavity. One of the main sources of detuning a cavity is microphonics. These low-frequent vibrations caused by vacuum pumps or underground noise are transferred to the cryostat and excite mechanical resonances of the cavity which may lead to frequency shifts larger than the bandwidth. To determine the mechanical resonance frequencies of the sc 325 MHz CH-cavity (Crossbar-H-Mode) simulations with ANSYS Workbench have been performed in a first step. Additionally, microphonics measurements were taken at room temperature as well as in a vertical cryostat at 4K in the cryo-lab of the IAP, Frankfurt University. Furthermore, the contraction of the cavity walls and the resulting frequency shift due to the cavity cool-down has been measured. A comparison between simulation results and the measured values is presented in this paper.

WEPWO007

Shape Optimization of a SRF Injector Cavity

emittance, solenoid, cathode, electron

2322

J.K. Sekutowicz
DESY, Hamburg, Germany
W.C. Grabowski, R. Nietubyć, T. Wasiewicz
NCBJ, Świerk/Otwock, Poland

In this contribution we present studies on the shape optimization of 1.6-cell cavity with solenoid for a 1-mA class photo injector, meant as an electron source for FEL facilities. The main criterion for the optimization was the lowest slice emittance. Inclination angle of the cavity back wall, solenoid position and magnetic field, amplitude of the accelerating field, and emission phase were varied in these studies in order to find the minimum of slice emittance at the distance of 1 m from a photocathode, located in center of the cavity back wall

WEPWO008

SRF Conical Half-wave Resonator Tuning Developments

simulation, target, resonance, cryomodule

2325

E.N. Zaplatin
FZJ, Jülich, Germany
A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302.
A conical Half-Wave Resonator is considered as an option for a first accelerating cavity for β=v/c=0.11 with the resonance frequency 162.5 MHz for a high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory (Project X). We present results of different options of the cavity mechanical tuning. The "standard" tuning method of beam port deformations is an effective tuning method still requiring a relatively high tuning pressure. The side tuning is considered as a novel option for the resonance frequency adjustment featuring lower tuning force and an option of the structure design for the resonator frequency shift self compensation.

WEPWO009

Numerical Coupling Analyses of BERLinPro SRF Gun

gun, simulation, SRF, cathode

2328

E.N. Zaplatin
FZJ, Jülich, Germany
W. Anders, A. Burrill, T. Kamps, J. Knobloch, O. Kugeler, A. Neumann
HZB, Berlin, Germany

BERLinPro is an approved ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity (1300 MHz, β=1) for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.8 MeV kinetic energy while limited by fundamental power coupler performance to about 230 kW forward power. The RF and beam dynamics gun cavity features 1.4 λ/2 cell resonator. We present results of mechanical structure developments of SRF gun. The main purpose of the whole structure optimization was the design of the gun helium vessel together with the tuner and stiffening rings to provide the simple construction for structure tuning with minimization of the cavity frequency dependence on external pressure. During the resonator tuning and external load structure deformations the cavity field profile variation along the beam path should stay within 5%.

WEPWO010

BERLinPro Seven-cell SRF Cavity Optimization and HOMs External Quality Factors Estimation

HOM, factory, SRF, simulation

2331

T. Galek, K. Brackebusch, T. Flisgen, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
J. Knobloch, A. Neumann
HZB, Berlin, Germany
B. Riemann, T. Weis
DELTA, Dortmund, Germany

Funding: Work funded by EU FP7 Research Infrastructure Grant No. 227579 and by German Federal Ministry of Research and Education, Project: 05K10HRC.
The main scope of this work is the optimization of the superconducting radio frequency (SRF) accelerating cavity design for the Berlin Energy Recovery Linac Project (BERLinPro)*. BERLinPro shall serve as a demonstrator for 100-mA-class ERLs with CW LINAC technology. High-current operation requires an effective damping of higher-order modes (HOMs) of the 1.3 GHz main-linac cavities. Consequently it is important, at the SRF cavity design optimization stage, to calculate the external quality factors of HOMs to avoid beam break up (BBU) instabilities. The optimization of the SRF cavity design consists of two steps. In the first step the cavities' end half-cells are tuned with respect to field flatness, effective shunt impedance and geometrical factor of the fundamental accelerating mode using robust eigenmode simulations. The second step involves frequency domain simulations and the extraction of external quality factors of HOMs from transmission S-parameter spectra using vector fitting procedure and an automated scheme to remove non-static poles **. The eigenmode,as well as the frequency domain simulations are performed using CST Microwave Studio ***.
* A. Neumann et al., Proc. of ICAP2012, pp. 278–280.
** T. Galek et al., Proc. of ICAP2012, pp. 152–154.
*** CST AG, http://www.cst.com

WEPWO011

In-vacuum Temperature Measurement of Niobium Components using Infrared Pyrometry during Electron Beam Welding Procedure

vacuum, electron, controls, shielding

2334

L. Monaco, P. Michelato, C. Pagani, D. Sertore
INFN/LASA, Segrate (MI), Italy
V. Battista, G. Corniani, M. Festa
Ettore Zanon S.p.A., Schio, Italy

Electron beam welding (EBW) is widely used in the construction of Niobium Superconducting RF cavities. The welding sequence of such a complex structure, foresees many welding operations. The welding parameters depend on many variables as the material thickness, but also on the component temperature before each weld. This paper presents a technique to measure the temperature of Nb components in vacuum during the EBW operation using an IR pyrometer placed outside the vacuum chamber through an appropriate vacuum viewport. With the current configuration the system can measure temperatures up to 350°C in the vacuum conditions of the EBW vacuum chamber (10-5-10^-6 mbar). The technique was used to optimize the time interval between each subsequent equatorial weld operation during Nb cavities production at Ettore Zanon, increasing the welding procedure reliability and decreasing the waiting time by control of the temperatures in the weld region. Moreover this technique can be generally used for in vacuum measurements of components from room temperature up to about 350 °C. Future developments are under way to make this technique compatible with UHV and increasing the measurement range.

WEPWO012

XFEL 3.9 GHz Prototype Cavities Tests

HOM, pick-up, status, diagnostics

2337

P. Pierini, M. Bertucci, A. Bosotti, C. Maiano, P. Michelato, L. Monaco, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
E.R. Harms
Fermilab, Batavia, USA
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy
E. Vogel
DESY, Hamburg, Germany

In preparation for the XFEL components production, three prototype cavities have been manufactured and vertically tested at INFN-LASA. Several tests, with and without HOM antennas and in a double cavity test configuration, have been performed. Further tests of one of the prototypes took place at FNAL, to validate results between the two test facilities. Results were consistent with those obtained at INFN-LASA.

WEPWO013

High Power Tests of Injector Cryomodule for Compact-ERL

cryomodule, HOM, radiation, accelerating-gradient

2340

E. Kako, D.A. Arakawa, K. Hara, T. Honma, H. Katagiri, Y. Kojima, Y. Kondo, S. Michizono, T. Miura, H. Nakai, H. Nakajima, K. Nakanishi, S. Noguchi, T. Shishido, T. Takenaka, K. Watanabe, Y. Yamamoto
KEK, Ibaraki, Japan
H. Hara, H. Hitomi, K. Sennyu
MHI, Kobe, Japan

In the cERL injector cryomodule, electron beams of 10 mA are accelerated from the beam energy of 500 keV to 5 MeV. A three 2-cell cavity system was chosen for the cERL injector. Each cavity is driven by two input couplers to reduce a required RF power handling capacity and also to compensate a coupler kick. In the cERL injector cryomodule, critical hardware components are not superconducting cavities but RF input couplers operating in CW mode. Six input couplers for the installation in the cryomodule were fabricated, and three pairs of input couplers were carefully conditioned. Costruction status, cool-down tests and high power RF test results on injector cryomodule for compact-ERL at KEK will be discussed in this paper.

WEPWO014

Rf Field-Attenuation Formulae for the Multilayer Coating Model

vacuum, coupling, electromagnetic-fields

2343

T. Kubo, T. Saeki
KEK, Ibaraki, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan

Formulae that describe the RF electromagnetic field attenuation in the multilayer coating model with a single superconductor layer and a single insulator layer deposited on a bulk superconductor are derived with a rigorous calculation based on the Maxwell equations and the London equation.

WEPWO015

Electron Beam Welding for High Gradient Superconducting Cavity

electron, superconducting-cavity, linear-collider, collider

2346

T. Kubo, Y. Ajima, H. Hayano, H. Inoue, S. Kato, T. Saeki, M. Sawabe, K. Umemori, Y. Watanabe, S. Yamaguchi, M. Yamanaka
KEK, Ibaraki, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
T. Nagata
ULVAC, Inc., Tsukuba, Japan

Relations between electron beam welding parameters and appearances of weld beads are studied. It was found that a beam generator position and a welding direction affect a geometry of weld bead dramatically. Carbon including contaminants found after the chemistry are also commented.

WEPWO016

Construction of Main Linac Cryomodule for Compact ERL Project

HOM, cryomodule, linac, radiation

2349

K. Umemori, K. Enami, T. Furuya, H. Sakai, M. Satoh, K. Shinoe
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
M. Sawamura
JAEA, Ibaraki-ken, Japan

Compact ERL (cERL), which is a test facility of ERL, is under construction at KEK, in Japan. At the first stage of cERL project, electron beam will be accelerated by 30 MV at main linac region. We have developed a main linac cryomodule, which contains two L-band 9-cell superconducting cavities. Cavity assembly work was carefully done at a class-10 clean room and HOM absorbers and cold windows of input couplers were successfully mounted on the cavities. Next, the frequency tuners, thermal anchors, magnetic shields and temperature sensors and so on were assembled to the cryomodule. Then, using a clean-booth, warm windows of the input couplers are connected to the cold windows and gate valves were also attached to the both ends of the cryomodule. Finally, the cryomodule was installed into the beamline of cERL and connected to a 2K cryogenic system. Target of alignment precision of the cavities, after cooling down to 2K, are set to be within 1 mm against the beamline. The first cool-down test, followed by low power and high power measurements, is scheduled within the year 2012.

WEPWO017

Efforts on Nondestructive Inspections for SC Cavities

target, laser, SRF, cryogenics

2352

Y. Iwashita, Y. Fuwa, M. Hashida, S. Sakabe, S. Tokita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
H. Hayano, K. Watanabe, Y. Yamamoto
KEK, Ibaraki, Japan
K. Otani
INRS-EMT, Varennes (Québec), Canada

The high resolution camera, so-called Kyoto Camera, inspecting the Sc cavity inner surface showed the importance of nondestructive inspections to improve yield in production of high performance SC Cavities. Further efforts have been continued for the inspection and the high resolution T-map, X-map and eddy current scanner have been developed. A radiography to detect small voids inside the Nb EBW seam with the target resolution of 0.1 mm is under investigation. We have carried out radiography tests with X-rays induced from an ultra short pulse intense laser.

WEPWO018

Status of the IHEP 1.3 GHz Superconducting RF Program for the ILC

cryomodule, SRF, vacuum, HOM

2355

J. Gao, Y.L. Chi, J.P. Dai, R. Ge, T.M. Huang, S. Jin, C. H. Li, S.P. Li, Z.Q. Li, H.Y. Lin, Y. Liu, Z.C. Liu, Q. Ma, Z.H. Mi, W.M. Pan, Y. Sun, J.Y. Zhai, T.X. Zhao, H.J. Zheng
IHEP, Beijing, People's Republic of China

The 1.3 GHz superconducting radio-frequency (SRF) technology is one of the key technologies for the ILC. IHEP is building an SRF Accelerating Unit, named the IHEP ILC Test Cryomodule (IHEP ILC-TC1), for the ILC SRF system integration study, high power horizontal test and possible beam test in the future. In this paper, we report the components test results and the assembly preparation of this cryomodule. Processing and vertical test of the large grain low-loss shape 9-cell cavity is done. Performance of the in-house made high power input coupler and tuner at room temperature reaches the ILC specification.

WEPWO019

Development of Frequency Measurement Setup for ADS 650MHz and 1.3GHz Superconducting RF Cavities at IHEP

SRF, linac, simulation, controls

2358

S. Jin, J. Gao, Y. Liu, Z.C. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng
IHEP, Beijing, People's Republic of China

The Accelerator Driven Sub-critical System (ADS) is under development in China, and the 650MHz β=0.82 superconducting RF cavity (SRF) has been chosen as a possible candidate to accelerate the proton bunches in the medium energy section from 360MeV to 1.5GeV [1]. In order to obtain quality management and quality assurance during fabrication, radio frequency measurements on parts and subassemblies of SRF cavities become a proper method [2]. In this paper, study on developing a new frequency measurement setup mainly for half cells, dumb-bells and end groups of ADS650MHz cavities at IHEP was reported. A digital pressure sense was assembled in the setup. Together with the simulation on the structural and frequency by ANSYS Workbench, a quantitative standard for the frequency measurement was built for the cavity fabrication. Since a 9-cell TESLA-Like cavity is also under study in the meantime, via a slight modification, the setup can be also used for it.

WEPWO021

ADS 650MHz β=0.82 Supercongducting Cavity Research Status

superconducting-cavity, proton, linac, status

2361

Z.C. Liu, J. Gao, S. Jin, Y. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng
IHEP, Beijing, People's Republic of China
J.X. Wang, H. Yu, H. Yuan
BIAM, Beijing, People's Republic of China

IHEP is developing a 650MHz β=0.82 supercongducting cavity for the China ADS project. The cavity is for the energy range of from 367MeV to 1500Mev. We have chosen a five cell cavity and optimized the cavity with Epk/Eacc and Bpk/Eacc to reach high gradient. Two cavity parts were fabricated and the EB welding is in process. This paper will show the fabrication status and measurement results.

WEPWO022

IHEP03 Fabrication and Testing Status

niobium, HOM, cryomodule, status

2364

Z.C. Liu, J. Gao, S. Jin, Y. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng
IHEP, Beijing, People's Republic of China
J.X. Wang, H. Yu, H. Yuan
BIAM, Beijing, People's Republic of China

IHEP is developing RF superconducting technology with different type of superconducting cavities. Tesla-like cavity which is designed by KEK is one of them. We have fabricated all the parts of the cavity using Nb material from Ningxia and cavity welding will be started soon. This paper will show the cavity fabrication procedures and measurement results.

WEPWO023

High Current Superconducting Cavity Study and Design

superconducting-cavity, linac, accelerating-gradient, electron

2366

Z.C. Liu, J. Gao, S. Jin, Y. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng
IHEP, Beijing, People's Republic of China
F. Wang
PKU, Beijing, People's Republic of China

Funding: Project 11275226 supported by NSFC
IHEP is developing a new type of high current superconducting cavity called slotted cavity proposed in 2010. The cavity is suitable for accelerating high beam current in Energy Recovery Linac (ERL). The cavity can extremely dump high order modes (HOMs) in the cavity to keep a high beam current threshold in the linac. We have studied and designed a three cell cavity and the fabrication is under going.

WEPWO025

Preliminary Design of 325 MHz Half-Wave Resonator

simulation, proton, controls, heavy-ion

2369

X.Y. Zhang, X. Chen, Z.Q. Li, Q. Ma, W.M. Pan, Y. Sun, G.W. Wang, Q.Y. Wang, B. Xu, G.Y. Zhao
IHEP, Beijing, People's Republic of China

Funding: This work is supported by the "Strategic Priority Research Program" of CAS.
The Half-Wave Resonator (HWR) has been widely used in proton and heavy ion accelerators, for it has particular advantages of accelerating low energy charged particles. Preliminary design of a 325 MHz β=0.12 superconducting HWR cavity has been proposed at Institute of High Energy Physics (IHEP). The basic geometric parameters choices of the cavity are based upon theoretical model and numerical calculation, and then the RF performances are optimized by extensive electromagnetic simulations. In this paper, the detailed mechanical analysis, frequency control, and the considerations for fabrication of the 325 MHz HWR cavity are also presented.

WEPWO026

HOM Parameters Simulation and Measurement Result of the IHEP02 Low-loss Cavity

HOM, dipole, damping, wakefield

2372

H.J. Zheng, J. Gao, S. Jin, Y. Liu, Z.C. Liu, Z.H. Mi, J.Y. Zhai, T.X. Zhao
IHEP, Beijing, People's Republic of China
H. Yuan
BIAM, Beijing, People's Republic of China

In cavities , there exists not only the fundamental mode which is used to accelerate the beam but also higher order modes(HOMs). The higher order modes excited by beam can seriously affect beam quality, especially for the higher R/Q mode. This paper reports on recent measurements of higher order modes in the IHEP-2 low-loss SRF cavity. Using different methods, the Qext of the dangerous modes passband are got. This result is compared with TESLA result. R/Q of the first three passbands are also got by CST and compared with the results of TESLA cavity and STFBaseline cavity.

WEPWO028

10×10mm2 MgB2 Film Fabricated by HPCVD as a Candidate Material for SRF Cavit

SRF, superconductivity, radio-frequency, heavy-ion

2375

F. He, K.X. Liu, Z. Ni, D. Xie
PKU, Beijing, People's Republic of China
Q. Feng
Peking University, Beijing, People's Republic of China

Magnesium diboride (MgB2) is one of candidate material for superconducting radio frequency cavities because of its good features: high transition temperature of ~39K and absence of weak links between grains which prevents other high-Tc superconducting materials, such as YBCO. Previous study of MgB2 are mainly focused on the films’ superconducting properties which are fabricated on Al2O3, SiC or some metal substrates with small scale less than 10×10 mm2. In this work we explore a technique to deposit clean and large-scale MgB2 films on Mo substrate, which is expected to provide a probable way to fabricate MgB2 thin-film cavities.. The measurement results show that its superconducting properties and mechanical behaviors are as good as those fabricated on small-scale metal substrates.

WEPWO029

Design of a SRF Quarter Wave Electron Gun at Peking University

electron, gun, simulation, SRF

2378

P.L. Fan, K.X. Liu, S.W. Quan, F. Zhu
PKU, Beijing, People's Republic of China

Funding: Work supported by National Basic Research Project (No. 2011CB808302) and National Natural Science Funds (No. 11075007)
Superconducting RF electron guns hold out the promise of very bright beams for use in electron injectors, particularly in future high average power free-electron lasers (FELs) and energy recovery linacs (ERLs). Peking University is designing a new SRF gun which is composed of a quarter wave resonator (QWR) and an elliptical cavity. Comparing to the elliptical cavity, the QWR is sufficiently compact at the same frequency and its electric field is quasi-DC. We have finished the preliminary design of the QWR cavity. The simulation shows that multipacting is not a critical issue for our cavity structure. Beam dynamic simulation of the QWR cavity is also presented.
contact author : zhufeng7726@pku.edu.cn

WEPWO036

Conceptual Design of a Superfluid Superconducting Third Harmonic RF System for the SSRF Storage Ring

superconducting-cavity, cryogenics, controls, synchrotron

2381

H.T. Hou, J.F. Liu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
J.F. Liu
Shanghai KEY Laboratory of Cryogenics & Superconducting RF Technology, Shanghai, People's Republic of China

Harmonic cavity can improve the beam quality through bunch size lengthening which includes providing Landau damping, suppressing coupled bunch instability and microwave instability, enhancing the beam current per bunch besides the beam lifetime improvement. A passive third harmonic superconducting cavity operating at super fluid liquid helium has been proposed for the SSRF storage ring with compromise on the required harmonic voltage, limited installation space and dissipated cryogenic power. This paper will mainly present the conceptual design of the harmonic rf system including the requirement of SSRF, a brief review on beam dynamics of harmonic rf system and the harmonic cavity choice.

WEPWO039

Prototyping of TEM-like Mode Resonators in the RAON

multipactoring, niobium, electron, simulation

2384

H.C. Jung, M.O. Hyun, D. Jeon, H.J. Kim
IBS, Daejeon, Republic of Korea

Preliminary electric-magnetic designs of TEM-like mode resonators(a quarter wave resonator, a half wave resonator, two single spoke resonators) are accomplished for the superconducting linear accelerator in the RAON. Resonant cavities are numerically optimized using a CST MWS code to obtain higher E-field gradient along the beam line in conditions of the peak E-field and B-field is less than 30MV/m, 60mT respectively. Prototyping test of a quater wave resonator of optimum beta 0.047 using OFC(Oxygen Free Cupper)is in progress to analyze resonant frequency shifting by tolerances in fabrication process and external perturbations. It is compared with expected one using compuational codes.

WEPWO040

Design of HWR at RISP

simulation, quadrupole, electromagnetic-fields, niobium

2387

G.-T. Park, H.J. Cha, H.C. Jung
IBS, Daejeon, Republic of Korea

At RISP, superconducting cavity resonators to accelerate the various ions in high current are being developed. In particular, hal-wave resonator (HWR) will be used for β=0.12, f=162.5 MHz. Here we present the structural analysis of HWR, which includes the prediction of resonant frequency shift during the manufacturing and testing process, stiffening measures to minimize the shift, and the tuning mechanism. The processes of welding, polishing, vacuuming, cooling (to crygenic temperature)as well as Lorentz force, helium pressure fluctuation, microphonics, and interaction with the helium vessel and tuning system will be simulated optimizing the frequency shift.

WEPWO041

Beam Commissioning Superconducting RF Cavities for PLS-II Upgrade

SRF, vacuum, storage-ring, LLRF

2390

Y.U. Sohn, M.-H. Chun, J.Y. Huang, Y.D. Joo, S.H. Nam, C.D. Park, H.J. Park, I.S. Park, I.H. Yu
PAL, Pohang, Kyungbuk, Republic of Korea

Two superconducting RF cavities were commissioned with electron beam at PLS-II, which is upgraded machine from PLS with 3 GeV, 20 insertion devices, and now on user service. These srf cavities have been prepared during last 3 years. Each cavity was tested with higher than 2 MV rf voltage and 125 kW standing wave power at CW mode after installation at storage ring. PLS-II is on user operation with 200 mA beam current now, and on the way of beam current improvement upto 400mA, by synchrotron conditioning for beam chamber and in-vacuum udulators. Upto 200 mA beam current no beam instability from the higher order modes is observed. With top-up mode operation, the errors of amplitude of rf field and phase are recorded as 0.3% and 0.3 degree peak to peak, respectively during one day. Successful PLS-II upgrade with hardware and its designed performance will be declared at the end of 1st half user run in 2013.

WEPWO042

Dubna-Minsk SRF Technology Development Status Report

cryogenics, niobium, coupling, electron

2393

N.S. Azaryan, Ju. Boudagov, D.L. Demin, V.V. Glagolev, G. Shirkov, G.V. Trubnikov
JINR, Dubna, Moscow Region, Russia
M.A. Baturitsky, N.M. Shumeiko
NC PHEP BSU, Minsk, Belarus
S.E. Demyanov, E.Yu. Kaniukov
Scientific-Practical Materials Research Centre of the National Academy of Sciences of Belarus, Minsk, Belarus
A. Ermakov, W. Singer, X. Singer
DESY, Hamburg, Germany
V.A. Karpovich, N.V. Liubetsky
BSU, Minsk, Belarus
S.V. Kolosov, A.A. Kurayev, A.O. Rak, A.K. Sinitsyn
Belarus State University of Informatics and Radioelectronics (BSUIR), Minsk, Belarus
S.I. Maximov, V.N. Rodionova
Belarussian State University, Scientific Research Institute of Nuclear Problems, Minsk, Belarus
A. Parshuto, V.S. Petrakovsky, I.L. Pobol, A.I. Pokrovsky, S.V. Yurevich, A.Yu. Zhuravsky
Physical-Technical Institute of the National Academy of Sciences of Belarus, Minsk, Belarus

In 2011 Dubna-Minsk collaboration started an activity on the development and manufacture the series of 1.3 GHz superconducting Nb cavities in the enterprises in Belarus. The current status of this work is presented in this report. Main EM characteristics of the cavity were calculated and the shop drawings for cavity fabrication were developed. Two test-benches were assembled for RF-tests of the cavities at room temperature and at liquid helium temperature. The measured SWR was about 1.01 due to special matching device developed for that. This measurement technique was applied to the single-cell cavity from FNAL at power level nearby 10 mW. Measured resonant frequency was about 1.27 GHz, while the measured Q-factor was 2.8·10⁴ at room temperature and more than 10⁸ at liquid helium temperature. To evaluate mechanical properties of sheet Nb and of model materials (Cu and Al), a number of tests were made. Series of half-cells were fabricated of Al to test the technique of hydraulic deep-drawing that will be used in production of Nb cavities. The modes for electron-beam welding of sheet Nb were explored and the first welding seams were tested. The method of chemical treatment of cavities was also elaborated.

Poster WEPWO042 [0.897 MB]

WEPWO045

RF Multipolar Characterization of the Latest LHC Deflecting Cavities

multipole, dipole, luminosity, extraction

2402

M. Navarro-Tapia, R. Calaga, A. Grudiev
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study (a sub-system of HL-LHC) is cofunded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
Deflecting cavity geometries considered for the Large Hadron Collider (LHC)crab scheme lack axial symmetry resulting in non-zero higher-order components of the deflecting field. A formalism to express the higher-order multipoles was developed and applied on previous cavity designs to characterize their influence on the beam stability. In this paper, the radio frequency (RF) multipoles are numerically estimated for the latest cavity geometries and compared to the older versions. A sensitivity study is carried to understand the numerical error levels and define mechanical tolerances.

WEPWO046

First Test Results of the 4-rod Crab Cavity

vacuum, niobium, pick-up, coupling

2405

R. Calaga, L.S. Alberty Vieira, S. Calatroni, O. Capatina, E. Ciapala, L.M.A. Ferreira, E. Jensen, P. Maesen, A. Mongelluzzo, T. Renaglia, M. Therasse
CERN, Geneva, Switzerland
P.K. Ambattu, D. Doherty, B.D.S. Hall, C. Lingwood
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
G. Burt
Lancaster University, Lancaster, United Kingdom

Funding: The HiLumi LHC Design Study (a sub-system of HL-LHC) is cofunded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The first prototype crab cavity with the 4-rod geometry has undergone surface treatment and cold testing. Due to the complex geometry and unique fabrication procedure, RF validation of the field at beyond the nominal operating voltage at a sufficiently high Q0 is an important pre-requiste. Preliminary results of the first cold tests are presented along with cavity performance at different stages of the cavity processing is described.

WEPWO047

A Double Quarter-Wave Deflecting Cavity for the LHC

HOM, multipole, higher-order-mode, simulation

2408

R. Calaga
CERN, Geneva, Switzerland
S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, Q. Wu, B. P. Xiao
BNL, Upton, Long Island, New York, USA

Funding: The HiLumi LHC Design Study (a sub-system of HL-LHC) is cofunded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404
An asymmetric quarter wave deflecting cavity at 400 MHz for crab crossing in the LHC was already proposed in 2011. Due to improved cancellation of on-axis longitudinal field and the higher order components of the deflecting field, a symmetric version is now considered as the baseline for the quarter wave geometry. Relevant RF properties of the symmetric cavity are compared to the original asymmetric cavity. Some aspects of input coupler design, higher order modes, multipacting and frequency tuning are also addressed.

WEPWO048

Investigation of a Ridge-loaded Waveguide Structure for CLIC X-band Crab Cavity

damping, HOM, beam-loading, impedance

2411

V.F. Khan, R. Calaga, A. Grudiev
CERN, Geneva, Switzerland

In conventional crab cavities the TM11 mode is used to deflect the beam. In a linear collider such as CLIC, it is necessary to damp all the other modes, namely the accelerating i.e. lower order mode (LOM), same order mode (SOM) and higher order modes (HOMs). In addition to this, as the TM11 mode is not the fundamental mode, it is generally not excited with the highest shunt impedance. This necessitates damping of the high shunt impedance modes to acceptable level. Here we report on the investigation of an alternative design of the X-band crab cavity for CLIC based on ridge-loaded waveguide. In this type of cavity, the deflecting mode is the fundamental mode and has the maximum shunt impedance. However, the geometry of the cavity is chosen to optimise the ratio of group velocity to shunt impedance to minimise the effect of beam loading. The other modes are excited above the crabbing mode and are damped using wave-guides. Another advantage of this type of cavity is, unlike the conventional TM11 mode cavities, the e.m. surface fields do not peak at the iris. This provides ample margin to optimise the cavity geometry and reach the desired field distribution.

WEPWO049

A Proposal for an ERL Test Facility at CERN

linac, electron, HOM, SRF

2414

R. Calaga, E. Jensen
CERN, Geneva, Switzerland

An energy recovery linac at 300-400 MeV is proposed as a test facility using a two-pass two-cryomodule concept as a proof of principle for a future ERL based electron-ion collider. This facility will enable both the development and validation of the required SRF technology performance and ERL specific beam dynamics essential for the future collider. Furthermore, the test facility can be used as the injector to the main linac in future. The test facility proposal, its potential uses and some aspects of the RF system are presented.

WEPWO050

Mechanical Study of 400 MHz Double Quarter Wave Crab Cavity for LHC Luminosity Upgrade

simulation, luminosity, vacuum, electron

2417

B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, Q. Wu
BNL, Upton, Long Island, New York, USA
L. Alberty Vieira, R. Calaga
CERN, Geneva, Switzerland
T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA

A prototype double quarter wave crab cavity was designed for the Large Hadron Collider luminosity upgrade. A finite element model is used to simulate the mechanical properties of the crab cavity. The results are presented and a reinforcement concept is proposed to meet the safety requirements. The reinforcement components, as well as the cavity, are presently being fabricated at Niowave Inc.

WEPWO051

Manufacture of a Compact Prototype 4R Crab Cavity for HL-LHC

niobium, luminosity, vacuum, electron

2420

G. Burt, B.D.S. Hall, C. Lingwood
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
L. Alberty Vieira, R. Calaga, O. Capatina
CERN, Geneva, Switzerland
C.H. Boulware, D. Gorelov, T.L. Grimm, C. Krizmanich, T.S. Lamie
Niowave, Inc., Lansing, Michigan, USA
C. Hill, P.A. McIntosh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.A. Rimmer, H. Wang
JLAB, Newport News, Virginia, USA

Funding: This work has been funded by the EU through EUCARD and HiLumi and by STFC via the Cockcroft Institute.
A prototype compact SRF deflecting cavity has been manufactured for LHC. The base of the cavity has been machined out of large grain niobium ingot to allow the manufacture of the complex rod profile. Stiffening rods have been used to increase the mechanical strength of the outer can. Details of the cavity design and manufacture will be discussed.

WEPWO053

SRF Development for a MW Proton Source at Fermi National Accelerator Laboratory

cryomodule, linac, SRF, HOM

2423

T.T. Arkan, C.M. Ginsburg, A. Grassellino, S. Kazakov, T.N. Khabiboulline, T.H. Nicol, Y. Orlov, T.J. Peterson, L. Ristori, A. Romanenko, A.M. Rowe, N. Solyak, A.I. Sukhanov, V.P. Yakovlev
Fermilab, Batavia, USA

Funding: Work supported by the US Department of Energy
Fermilab is planning a megawatt-level proton beam facility utilizing niobium superconducting RF (SRF) cavities. Project X at Fermilab will eventually provide high-intensity beams for research into the nature of matter at the "intensity frontier". Research and development in several areas will bring the SRF technology to the level needed for this application. Among developments in SRF being pursued with our national and international collaborators are 162.5 MHz half-wave resonators, 325 MHz single-spoke resonators, and two types of elliptical multi-cell 650 MHz cavities. Performance requirements for these cavities and cryomodules in continuous wave (CW) operation are extremely stringent in order to provide high accelerating gradients with acceptable total cryogenic load and overall accelerator capital and operating costs. This paper presents some highlights of the SRF R&D program and proton linac development work at Fermilab.

WEPWO054

Multistep Mechanical Analyses of Centrifugal Barrel Polishing Barrel and Cavity

simulation, SRF, acceleration, niobium

2426

M. Chen, C.A. Cooper, L. Ristori
Fermilab, Batavia, USA

Funding: US Department of Energy
Fermilab has successfully demonstrated the ability to improve the performance of damaged 1.3 GHz single cell and 9-cell Tesla–type cavities by using a modified centrifugal barrel polishing (CBP) process that leaves a mirror finish on the inside of the cavity. Fermilab now is developing and constructing a new CBP machine which can handle both 650 MHz and 1.3 GHz cavities. The new machine will have a larger moment arm and therefore impart more force on the cavity and machine. Because of these increased forces the effects on cavity supports and machine design were examined. This paper will document the multistep mechanical analyses for the CBP barrel and cavity, calculations of the fatigue life and the requirements for the structural welds.

WEPWO055

Fabrication and Testing of SSR1 Resonators for PXIE

cryomodule, linac, vacuum, beam-transport

2429

L. Ristori, M.H. Awida, P. Berrutti, T.N. Khabiboulline, M. Merio, D. Passarelli, A.M. Rowe, D.A. Sergatskov, A.I. Sukhanov
Fermilab, Batavia, USA

Fermilab is in the process of constructing a proton linac to accelerate a 1 mA CW beam up to 30 MeV. It will be a test for the front end of Project X and known as the Project X Injector Experiment (PXIE). The major goal of PXIE is the validation of the Project X concept and mitigation of technical risks. It is expected to be constructed in the period of 2012-2016. The PXIE linac consists of a Ion source and LEBT, a 162.5 MHz RFQ, a MEBT, a 162.5 MHz HWR cryomodule (designed and built at ANL) and a 325 MHZ SSR1 cryomodule (designed and built at FNAL). In this paper we present the recent advances in the development of the SSR1 resonators at Fermilab. Several bare SSR1 resonators have been processed, heat-treated and tested successfully in the Fermilab Vertical Test Stand. The outfitting of helium vessels is in process and the coarse-fine frequency tuning system has been designed and is currently being procured and tested. Details of the power coupler are also discussed.

WEPWO056

Update of the Mechanical Design of the 650 MHZ β=0.9 Cavities for Project X

simulation, resonance, niobium, linac

2432

I.V. Gonin, M.H. Awida, M.H. Foley, C.J. Grimm, T.N. Khabiboulline, Y.M. Pischalnikov, V.P. Yakovlev
Fermilab, Batavia, USA

Five-cell elliptical 650 MHz β=0.9 cavities to accelerate 1 mA of average H⁻ beam current in the range 520-3000 MeV of the Project X Linac are currently planned. We will present the results of optimization of mechanical design of cavities with their Helium Vessel. We discuss the efforts to optimize the mechanical stability of the cavity versus the Helium bath pressure fluctuations, cavity tunability. We present also modal and thermal analysis; discuss tuner options and other issues.

WEPWO057

Update of SSR2 Cavities Design for Project X and RISP

linac, cryomodule, simulation, heavy-ion

2435

M. Merio, M.H. Awida, P. Berrutti, I.V. Gonin, T.N. Khabiboulline, D. Passarelli, Y.M. Pischalnikov, L. Ristori, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Single spoke resonators SSR2 (f=325 MHz) are under development at Fermilab. These cavities can meet requirements of Project X (FNAL) and RISP (Korea). The initial design of SSR2 cavities has been modified and optimized in order to satisfy the necessities of both projects. This paper will discuss the RF optimization for a single spoke resonator with a 50 mm beam pipe aperture and an optimal beta of 0.51. Further, the approach to the mechanical design of the cavity will be presented together with the proposed helium vessel. The latter is intended to guarantee a low He pressure sensitivity df/dp of the entire jacketed SSR2 and actively control the microphonics.

WEPWO058

Recent Progress at Fermilab Controlling Lorentz Force Detuning and Microphonics in Superconducting Cavities

resonance, controls, cryomodule, SRF

2438

W. Schappert, Y.M. Pischalnikov
Fermilab, Batavia, USA

Funding: Work is supported by U.S. Department of Energy
SRF cavities are susceptible to detuning by mechanical deformations induced by the Lorentz force and microphonics. Providing the RF overhead required to maintain the accelerating gradient in detuned cavities can increase both the capital and operating costs of superconducting accelerators. Recent work at Fermilab has shown that active vibration control using a piezo actuator can reduce both Lorentz Force detuning and microphonics to the point where negligible RF overhead is required to maintain the accelerating gradient.

WEPWO059

Cornell's HOM Beamline Absorbers

HOM, linac, damping, cryomodule

2441

R. Eichhorn, J.V. Conway, Y. He, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, P. Quigley, J. Sears, V.D. Shemelin, N.R.A. Valles
CLASSE, Ithaca, New York, USA

The proposed energy recovery linac at Cornell aims for high beam currents and short bunch lengths, the combination of which requires efficient damping of the higher order modes (HOMs) being present in the superconducting cavities. Numerical simulations show that the expected HOM power could be as high as 200 W per cavity with frequencies ranging to 40 GHz. Consequently, a beam line absorber approach was chosen. We will review the design, report on first results from a prototype and discuss further improvements.

WEPWO060

The CW Linac Cryo-module for Cornell’s ERL

linac, HOM, damping, status

2444

R. Eichhorn, Y. He, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich
CLASSE, Ithaca, New York, USA

Cornell University has proposed an energy-recovery linac (ERL) based synchrotron-light facility which can provide greatly improved X-ray beams due to the high electron-beam quality that is available from a linac. As part of the phase 1 R&D program, critical challenges in the design were addressed, one of them being a full linac cryo-module. It houses 6 superconducting cavities- operated at 1.8 K in cw mode- HOM absorbers and a magnet/ BPM section. We will present the design being finalized recently and report on the fabrication status that started in late 2012.

WEPWO061

Readiness for the Cornell ERL

emittance, cathode, linac, laser

2447

G.H. Hoffstaetter, A.C. Bartnik, I.V. Bazarov, D.H. Bilderback, M.G. Billing, J.D. Brock, J.A. Crittenden, L. Cultrera, D.S. Dale, J. Dobbins, B.M. Dunham, R.D. Ehrlich, M. P. Ehrlichman, R. Eichhorn, K. Finkelstein, E. Fontes, M.J. Forster, S.J. Full, F. Furuta, D. Gonnella, S.W. Gray, S.M. Gruner, C.M. Gulliford, D.L. Hartill, Y. He, R.G. Helmke, K.M.V. Ho, R.P.K. Kaplan, S.S. Karkare, V.O. Kostroun, H. Lee, Y. Li, M. Liepe, X. Liu, J.M. Maxson, C.E. Mayes, A.A. Mikhailichenko, H. Padamsee, J.R. Patterson, S.B. Peck, S. Posen, P. Quigley, P. Revesz, D.H. Rice, D. Sagan, J. Sears, V.D. Shemelin, D.M. Smilgies, E.N. Smith, K.W. Smolenski, A.B. Temnykh, M. Tigner, N.R.A. Valles, V. Veshcherevich, A.R. Woll, Y. Xie, Z. Zhao
CLASSE, Ithaca, New York, USA

Funding: Supported by NSF award DMR-0807731 and NY State
Energy-Recovery Linacs (ERLs) are proposed as drivers for hard x-ray sources because of their ability to produce electron bunches with small, flexible cross sections and short lengths at high repetition rates. Cornell University has pioneered the design and hardware for ERL lightsources. This preparatory research for ERL-lightsource construction will be discussed. Important milestones have been achieved in Cornell's prototype ERL injector, including the production of a prototype SRF cavity that exceeds design specifications, the regular production of long-lived and low emittance cathodes, the acceleration of ultra-low emittance bunches, and the world-record of 65 mA current from a photoemission DC gun. We believe that demonstration of the practical feasibility of these technologies have progressed sufficiently to allow the construction of an ERL-based lightsource like that described in [erl.chess.cornell.edu/PDDR].

WEPWO065

Optimization of Elliptical SRF Cavities for β <1

SRF, HOM, niobium, simulation

2450

V.D. Shemelin
CLASSE, Ithaca, New York, USA
J. Newbolt
Rochester University, Rochester, New York, USA

Funding: NSF award DMR-0807731
A systematic approach to optimization of SRF cavities which was done earlier for β=1 is extended to β<1 Some improvements for earlier developed designs are proposed.

WEPWO066

Frequency Control in the Cornell-ERL Main-Linac Cavity Production

niobium, target, controls, LabView

2453

V.D. Shemelin, B. Bullock, P.R. Carriere, B. Clasby, R. Eichhorn, B. Elmore, J.J. Kaufman, J. Sears
CLASSE, Ithaca, New York, USA

Funding: NSF award DMR-0807731
Cavity fabrication can be broken down into three main stages: deep-drawing cups, welding the cups in pairs to obtain “dumbbells” and end groups, and, finally, welding the obtained components into a completed cavity. Frequency measurements and precise machining were implemented after the second stage. A custom RF fixture and data acquisition system were used for this purpose. The system comprised of a mechanical press with RF contacts, a network analyzer, a load cell and custom LabVIEW and MATLAB scripts. To extract the individual frequencies of the cups from these measurements, algorithm of calculations was developed. Corrections for the ambient environment were also incorporated into the measurement protocol. Two 7-cell 1.3 GHz cavities were produced with high field flatness immediately after fabrication.

WEPWO067

Conditions for the Existence of 1- and 2-point Multipactor in SRF Cavities

electron, simulation, multipactoring, superconductivity

2456

V.D. Shemelin
CLASSE, Ithaca, New York, USA

Funding: NSF award DMR-0807731
One- and two-point multipactor (MP) in RF cavities are well-known phenomena. However, conditions when this or the other type of discharge develops were not clearly defined up to now. Here, an explicit description of these two types of the MP is presented, geometrical parameters, or figures of merit, responsible for initiation of the MP defined, and areas of their existence delineated. Small sizes of trajectories in the MP require a very precise calculation of fields for simulations. On the other hand, due to these small sizes, fields can be presented as the Taylor expansions and trajectories can be found solving ordinary differential equations of motion. Conditions of motion stability and influence of the Miller force are also accounted.

WEPWO068

Cornell ERL Main Linac 7-cell Cavity Performance in Horizontal Test Cryomodule Qualifications

linac, cryomodule, higher-order-mode, HOM

2459

N.R.A. Valles, R. Eichhorn, F. Furuta, G.M. Ge, D. Gonnella, Y. He, K.M.V. Ho, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, S. Posen, P. Quigley, J. Sears, V. Veshcherevich
CLASSE, Ithaca, New York, USA

Funding: NSF DMR-0807731
Cornell has recently ﬁnished producing and testing the ﬁrst prototype 7-cell main linac cavity for the Cornell Energy Recovery Linac, and completed the prototype cavity qualification program. This paper presents quality factor results from the horizontal test cryomodule (HTC) measurements, from the HTC-1 through HTC-3 experiments, reaching Q's up to 6 x 10¹⁰ at 1.6 K. We investigate the effect of thermal cycling on cavity quality factor and show that high quality factors can be preserved from initial mounting to fully outfitting the cavity with side-mounted input coupler and beam line absorbers. We also discuss the production of six additional main-linac cavities as we progress toward constructing a full 6-cavity cryomodule.

WEPWO069

HOM Studies of the Cornell ERL Main Linac Cavity: HTC-1 Through HTC-3

HOM, cryomodule, linac, higher-order-mode

2462

N.R.A. Valles, R. Eichhorn, G.H. Hoffstaetter, M. Liepe
CLASSE, Ithaca, New York, USA

Funding: Supported by NSF grant DMR-0807731
The Cornell energy recovery linac is designed to run a high energy (5 GeV), high current (100 mA), very low emittance beam (30 pm at 77 pC bunch charge). A major challenge to running such a large current continuously through the machine is the effect of strong higher-order modes(HOMs) that can lead to beam breakup. This paper presents the results of HOM studies for the prototype 7-cell cavity installed in a horizontal test cryomodule (HTC) from initial RF test, to being fully outfitted with side-mounted input coupler and beam line absorbers. We compare the simulated results of the optimized cavity geometry with measurements from all three HTC experiments.

WEPWO071

Quench and High Field Q-SLOP Studies using a Single Cell Cavity with Artificial Pits

SRF, niobium, feedback, factory

2465

Y. Xie, G.H. Hoffstaetter, M. Liepe
CLASSE, Ithaca, New York, USA

Surface defects such as pits have been identified as some of the main sources of limitations of srf cavity performance. A single cell cavity was made with 30 artificial pits in the high magnetic field region to gain new insight in how pits limit the cavity performance. The test of the pit cavity showed clear evidence that the edges of two of the largest radius pits transitioned into the normal conducting state at field just below the quench field of the cavity, and that the quench was indeed induced by these two pits. Insights about quench and non-linear rf resistances will be presented.

WEPWO072

HOM Damping Coupler Design for the 400-MHz RF Dipole Compact Crab Cavity for the LHC HiLumi Upgrade

HOM, dipole, damping, coupling

2468

Z. Li, L. Ge
SLAC, Menlo Park, California, USA
S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA

Funding: Work partially supported by the US DOE through the US LHC Accelerator Research Program (LARP), and by US DOE under contract number DE-AC02-76SF00515.
Crab cavities are adapted as the baseline design for the LHC HiLumi upgrade to achieve head-on beam-beam collisions for further improvement in luminosity. A 400-MHz compact RF dipole crab cavity design was developed by a joint effort between Old Dominion University and SLAC under the support of US LARP program. This design has shown very favorable RF parameters and can fit into the available beamline spacing for either vertical and horizontal crabbing schemes. A niobium prototype cavity based on such a design has been manufactured for vertical test. In addition, there are stringent wakefield requirements that needed to be met for such a cavity in order to preserve the quality of the circulating beams. In this paper, we will discuss different damping schemes for such a compact design and present the HOM coupler designs to meet the damping requirements.

WEPWO073

RF Design Optimization for New Injector Cryounit at CEBAF

coupling, cryomodule, SRF, injection

2471

H. Wang, G. Cheng, F.E. Hannon, A.S. Hofler, R. Kazimi, J.P. Preble, R.A. Rimmer
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A new injector superconducting RF (SRF) cryounit with one new 2-cell, β=0.6 cavity plus one refurbished 7-cell, β=0.97, C100 style cavity has been re-designed and optimized for the engineering compatibility of existing module for CEBAF operation. The optimization of 2-cell cavity shape for longitudinal beam dynamic of acceleration from 200keV to 533keV and the minimization of transverse kick due to the waveguide couplers to less than 1 mrad have been considered. Operating at 1497MHz, two cavities has been designed into a same footprint of CEBAF original quarter cryomodule to deliver an injection beam energy of 5MeV in less than 0.27o rms bench length and a maximum energy spread of 5keV.

WEPWO076

Development of Ultra High Gradient and High Q0 Superconducting Radio Frequency Cavities

niobium, SRF, acceleration, cryogenics

2474

R.L. Geng, W.A. Clemens, J. Follkie, T. Harris, D. Machie, R. Martin, A.D. Palczewski, E. Perry, G. Slack, R.S. Williams
JLAB, Newport News, Virginia, USA
C. Adolphsen, Z. Li
SLAC, Menlo Park, California, USA
J.K. Hao, Y.M. Li, K.X. Liu
PKU, Beijing, People's Republic of China
P. Kushnick
JLab, Newport News, Virginia, USA

Funding: Work supported by DOE. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We report on the recent progress at Jefferson Lab in developing ultra high gradient and high Q0 superconducting radio frequency (SRF) cavities for future SRF based machines. A new 1300 MHz 9-cell prototype cavity is being fabricated. This cavity has an optimized shape in terms of the ratio of the peak surface field (both magnetic and electric) to the acceleration gradient, hence the name low surface field (LSF) shape. The goal of the effort is to demonstrate an acceleration gradient of 50 MV/m with Q0 of 10¹⁰ at 2 K in a 9-cell SRF cavity. Fine-grain niobium material is used. Conventional forming, machining and electron beam welding method are used for cavity fabrication. New techniques are adopted to ensure repeatable, accurate and inexpensive fabrication of components and the full assembly. The completed cavity is to be first mechanically polished to a mirror-finish, a newly acquired in-house capability at JLab, followed by the proven ILC-style processing recipe established already at JLab. In parallel, new single-cell cavities made from large-grain niobium material are made to further advance the cavity treatment and processing procedures, aiming for the demonstration of an acceleration gradient of 50 MV/m with Q0 of 2·10¹⁰ at 2K.
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.

WEPWO077

Rf System Requirements for JLab’s MEIC Collider Ring

ion, electron, impedance, SRF

2477

S. Wang, R. Li, R.A. Rimmer, H. Wang, Y. Zhang
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The Medium-energy Electron Ion Collider (MEIC), proposed by Jefferson Lab, consists of a series of accelerators [1]. At the top energy are the electron and ion collider rings. For the ion ring, it accelerates five long ion bunches to colliding energy and rebunches ions into a train of very short bunches before colliding. A set of low frequency RF system is needed for the long ion bunch energy ramping. Another set of high frequency RF cavities is needed to rebunch ions. For the electron ring, superconducting RF (SRF) cavities are needed to compensate the synchrotron radiation energy loss. The impedance of the SRF cavities must be low enough to keep the high current electron beam stable. The preliminary design requirements of these RF cavities are presented.
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.

WEPWO079

Superconducting Single-spoke Cavities for High-velocity Applications

multipole, electron, higher-order-mode, linac

2480

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

Spoke cavities have been investigated for particle acceleration in the high-velocity regime. As part of these efforts, single-spoke cavities for particles traveling at the speed of light are being designed and built for proof-of-principle demonstration. We report here on the results of electromagnetic properties, design optimization, multipacting analysis, field non-linearities and higher order mode spectrum for a single-spoke cavity operating at 325 MHz.

WEPWO080

Compact Superconducting RF-dipole Cavity Designs for Deflecting and Crabbing Applications

dipole, multipole, HOM, higher-order-mode

2483

S.U. De Silva, A. Castilla, J.R. Delayen
ODU, Norfolk, Virginia, USA
A. Castilla
DCI-UG, León, Mexico

Over the years the superconducting parallel-bar design has evolved into an rf-dipole cavity with improved properties. The new rf-dipole design is considered for number of deflecting and crabbing applications. Some of those applications are the 499 MHz rf separator system for the Jefferson Lab 12 GeV upgrade, 400 MHz crabbing cavity system for the proposed LHC high luminosity upgrade, and 750 MHz crabbing cavity for the medium energy electron-ion collider in Jefferson Lab. In this paper we present the optimized rf design in terms of rf performance including rf properties, higher order mode properties, multipacting, multipole expansion for the above mentioned applications.

WEPWO082

Ferroelectric Based High Power Tuner for L-band Accelerator Applications

controls, linac, vacuum, simulation

2486

A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
S. Kazakov, V.P. Yakovlev
Fermilab, Batavia, USA
A.B. Kozyrev
LETI, Saint-Petersburg, Russia
E. Nenasheva
Ceramics Ltd., St. Petersburg, Russia

Funding: US Department of Energy
With this paper, we present our recent breakthrough with a new fast ferroelectric tuner development. The tuner is based on BST(M) ferroelectric elements (ε~150), which are designed to be used as the basis for L-band accelerator components intended for ERL, ILC, Project X and other applications. These new ferroelectric elements are to be fabricated for the new fast active tuner for SC cavities that can operate in air at low biasing DC fields. Note there were no reliable results on the long-term piezo actuators operations in CW regime. Specific features of ERL, ILC and Project X accelerator technology and challenges of the designs are high magnitude and phase stability of its operations. Mechanical vibrations, or microphonics affect the SRF resonator, while the ferroelectric tuners have shown extremely high tuning speed. We have demonstrated successful mitigation of the residual effects on the ferroelectric-metal interface along with the acceptable level of the overall loss factor of the tuner element. A new concepts of a tuning element based on low dielectric constant ferroelectrics along with fabrication technology of these new BST(M) ferroelectric elements will be presented.

WEPWO084

Improvement of the Q-factor Measurement in RF Cavities

dipole, coupling, pick-up, HOM

2489

W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi
Stony Brook University, Stony Brook, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S.
The Q values of Higher-order-modes (HOMs) in RF cavities are measured at room temperature with the 3 dB bandwidth reading by a network analyzer. The resonant curve distortion is created by the resonance splitting due to the ellipticity caused by manufacture tolerance and RF ports. Therefore, the measured Q values are usually lower than the simulated or theoretical Q values. In some cases, even only one mode’s Q can be measured with the 3 dB method. There may be two reasons for this happening. One is that only one mode was excited and the neighbor splitmode was close to 90° polarized; the other reason is that the resonant curve of one mode was distorted by the other mode too much to measure the 3dB range. In this paper, we resolve this issue by looking into the RF measurement setup, including cavity, input coupler and pick-up coupler, from the equivalent circuit and wave point of view. Based on the BNL3 copper prototype cavity, we compared these results from measurement and simulation.

WEPWO085

Commissioning SRF Gun for the R&D ERL at BNL

gun, SRF, HOM, simulation

2492

W. Xu, Z. Altinbas, S.A. Belomestnykh, I. Ben-Zvi, S. Deonarine, D.M. Gassner, H. Hahn, J.P. Jamilkowski, P. Kankiya, D. Kayran, N. Laloudakis, L. Masi, G.T. McIntyre, D. Pate, D. Phillips, T. Seda, K.S. Smith, A.N. Steszyn, T.N. Tallerico, R. Than, R.J. Todd, D. Weiss, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi, J. Dai
Stony Brook University, Stony Brook, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S.
The R&D ERL project at BNL aims to demonstrate a high charge, high current energy recovery linac. One of the key SRF system is the 704 MHz half-cell SRF gun. The SRF gun is designed to deliver up to 0.5 A beam at 2 MeV with 1 MW of CW RF power. The gun commissioning started in November 2012. The first photoemission beam from the SRF gun is expected in early 2013. This presentation will discuss the results of the SRF gun commissioning, and the performance of the high-power RF system.

WEPWO086

Split Higher Order Modes in Superconducting Cavities

resonance, dipole, HOM, higher-order-mode

2495

H. Hahn, S.A. Belomestnykh, W. Xu
BNL, Upton, Long Island, New York, USA

Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE and award no. DE-SC0002496 to Stony Brook University with the US DOE.
Split resonances are a common appearance in superconducting cavities and were studied here on the specific example of the TE11 dipole resonance in five-cell copper models of the ERL and BNL3. The BNL3 cavity was designed to be suitable for the envisioned electron-hadron collider eRHIC. Achieving the required high-current performance depends on avoiding beam break-up instabilities by minimizing the Higher Order Modes (HOM) Q-values. This was attempted in the design phase and will be done with appropriate mode dampers in operation. The availability of a copper model provided a convenient opportunity to confirm the design and to study potentially nefarious high-Q resonances. The appearance of split resonances impeded the HOM identification and the theoretical interpretation as elipticity deformation is presented in this report.

WEPWO087

Parameter Optimization for Laser Polishing of Niobium for SRF Applications

laser, niobium, SRF, target

2498

L. Zhao, M.J. Kelley
The College of William and Mary, Williamsburg, USA
M.J. Kelley, J.M. Klopf, C.E. Reece
JLAB, Newport News, Virginia, USA

Surface smoothness is critical to the performance of SRF cavities. As laser technology has been widely applied to metal machining and surface treatment, we are encouraged to use it on niobium as an alternative to the traditional wet polishing process where aggressive chemicals are involved. In this study, we describe progress toward smoothing by optimizing laser parameters on BCP treated niobium surfaces. Results show that microsmoothing of the surface without ablation is achievable.

Poster WEPWO087 [1.683 MB]

WEPEA019

Status of the J-PARC MA Loaded RF Systems

impedance, injection, proton, bunching

2537

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

Japan proton accelerator complex operates two cascaded synchrotrons, 3GeV RCS and 50GeV MR. The high electric field gradient magnetic alloy (MA) loaded cavities are used in both synchrotrons. The RF systems have no tuning control loop and the direct digital synthesis based fully digital low level RF guarantees the stable and reproducible proton acceleration. The feed-forward systems using the circulating beam current signals works efficiently to compensate the heavy beam induced voltage. In RCS, 11 RF systems are operating in a dual harmonic mode since December 2008. The longitudinal RF control based on the particle tracking performed effectively and the equivalent beam power of 530 kW was successfully demonstrated. The 260kW operation for the neutron users started in October 2012. In MR synchrotron, the 9th RF system was newly installed and became available as a 2nd harmonic RF system in November 2012. A 30 GeV proton of 200 kW beam power has been delivered to the T2K neutrino beam experiment with 2.48 sec repetition cycle. This paper summarizes the operation details and the status and features of the J-PARC RF systems.

WEPEA020

Commissioning of Beam Loading Compensation System in the J-PARC MR

impedance, beam-loading, injection, extraction

2540

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

Beam loading compensation is indispensable to accelerate high intensity proton beams in the J-PARC MR. The MA-loaded rf cavities in the MR are driven by the single harmonic (h=9) rf signals, while the cavity frequency response covers also the neighbor harmonics (h=8, 10). The wake voltage induced by the beam consists of the three harmonics (h=8, 9, 10). We employ the rf feedforward method to compensate the beam loading of these harmonics. The full-digital feedforward system was developed for the MR. We have successfully commissioned the feedforward patterns for all of eight cavities by using high intensity beams with 1.0·10¹⁴ ppp. We present the commissioning results. The impedance seen by the beam is reduced and the longitudinal oscillations due to the beam loading are reduced. By the beam loading compensation, high power beam operation at the beam power of 200 kW has been achieved.

WEPEA030

Simulation of Beam Capture Process in HIRFL-CSRm

simulation, acceleration, extraction, injection

2564

P. Li, P. Jiang, J.W. Xia, J.C. Yang, Y.J. Yuan
IMP, Lanzhou, People's Republic of China

In this paper, the beam capture processes are simulated in CSRm with the real RF cavity curves. By now, CSRm can accelerate all ions from protons up to the heaviest element, uranium, with variable energies and different efficiency. During the beam capture processes, the capture voltage and capture time must be cheese properly to avoid the beam loss. Moreover, the mismatch between the actual and the setting beam energy and space charge effect are investigated for high beam capture efficiency. The evolution of longitudinal phase space during the capture processes is presented in this simulation too.

WEPEA032

Estimation and Correction of the Uncontrolled Beam Loss due to the Alignment Error in the Low-energy Linear Accelerator of RAON

alignment, ion, linac, quadrupole

2570

J.G. Hwang, E.-S. Kim
Kyungpook National University, Daegu, Republic of Korea
D. Jeon, H.J. Kim
IBS, Daejeon, Republic of Korea

RAON(Rare isotope Accelerator Of Newness) mainly consists of the front-end system, ISOL system , re-accelerator for ISOL system, charge stripper section and main linear accelerator(Linac) for ECR ion source. Since the beam energy at the down-stream of the front-end system is low, 0.3~0.5 MeV/u, the trajectories of the beam is very sensitive the alignment error of the magnets and cavities at the entrance of the main Linac. It can be caused the uncontrolled beam loss due to the large amplitude of the trajectory. The effect of the alignment errors of the magnets and cavities is estimated and corrected by using analytical model which is based on analytical model and code TRACK. The calculation result based on the analytical model agrees very well with the simulation by using the TRACK code. Using the analytical model, the position and number of the corrector and Beam Position Monitor(BPM) in low energy Linac was determined to compensate the amplification of the beam trajectory under 400 um. We will present the result of the estimation of the alignment error and the correction using steering magnet with strip-line Beam Position Monitor (BPM) in a low energy section.

WEPEA040

Space Charge and Cavity Modeling for the ESS Linac Simulator

space-charge, linac, proton, simulation

2588

E. Laface, M. Eshraqi, R. Miyamoto
ESS, Lund, Sweden

The proton linac of the European Spallation Source will operate at unprecedented beam power of 5 MW. Such power requires a precise modeling of the beam dynamics in order to protect its components from losses. The high peak current of 62.5 mA produces a space charge force that dominates the dynamics at low energy, while the high gradient required to accelerate up to 2 GeV in the 500 m of linac length is challenging for the dynamics in the RF cavities. This paper presents modelings of the space charge force and RF cavities used in the ESS Linac Simulator. The simulator is under development as part of the XAL on-line model, and it will be adopted for the ESS linac operations.

WEPEA065

Beam Tests and Plans for the CERN PS Booster Wideband RF System Prototype

feedback, controls, LLRF, booster

2660

M.M. Paoluzzi, M. E. Angoletta, A. Findlay, M. Haase, M. Jaussi
CERN, Geneva, Switzerland

In the framework of the LHC Injectors Upgrade project (LIU) and in view of a complete replacement of the existing CERN PS Booster (PSB) RF systems, a prototype cavity has been installed beginning of 2012 in the machine. This modular, wideband (0.5 / 4 MHz), Finemet® loaded system uses solid-state power stages and includes fast RF feedback for beam loading compensation. In depth studies have been performed during 2012 to evaluate the system interaction with the new low-level digital electronics, its ability to accelerate the beam and cope with high beam intensity. The encouraging results suggest that this innovative approach can indeed be used to replace all the existing PSB RF systems but additional testing with a full scale prototype is required. This paper reports about the project status, the achieved results, the encountered difficulties and the foreseen prototype completion in preparation during 2013.

WEPEA076

Comparison of Taylor Maps with Radio Frequency Multipoles in a Thin Lens 6D Tracking Code

multipole, luminosity, collider, hadron

2687

D.R. Brett, R. Appleby
UMAN, Manchester, United Kingdom
J. Barranco, R. De Maria, R. Tomás
CERN, Geneva, Switzerland

Funding: HiLumi LHC Design Study is part of the High Luminosity LHC project and is part funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
SixTrack is a general purpose 6D thin lens tracking code used for dynamic aperture studies. In the high luminosity LHC upgrade it is proposed that crab cavities are used to enhance the luminosity. In this study, for the current proposed optics, we consider the use of RF multipoles and Taylor maps as methods to simulate crab cavity elements in the lattice.

WEPFI002

Acceptance Tests for the Spiral2 SC Linac RF Power Systems

linac, impedance, insertion, controls

2702

M. Di Giacomo
GANIL, Caen, France

Funding: This activity received founds from the EuCard RF Tech program
The Spiral2 SC linac uses solid state amplifiers ranging from 2,5 to 19 kW and external circulators to drive normal and superconducting cavities at 88.0525 MHz. The project has no manpower for in house development and all power devices are ordered to commercial companies. Robust acceptance tests have therefore been defined to check reliability with respect to our application. The papers describes the tests procedure and results on our first units.

WEPFI004

Commissioning of First 352.2 MHz - 150 kW Solid State Amplifiers at the ESRF and Status of R&D

booster, storage-ring, HOM, status

2708

J. Jacob, L. Farvacque, G. Gautier, M.L. Langlois, J.M. Mercier
ESRF, Grenoble, France

Funding: This work receives funding from the EU as work package WP7 in the FP7/CRISP project.
Four 352.2 MHz - 150 kW Solid State Amplifiers (SSA), based on the SOLEIL design and supplied by ELTA/AREVA, are in operation on the ESRF booster since April 2012. A number of interesting effects were observed during commissioning that are inherent to the combination of many RF amplifier modules at high power. While it has only little impact on the booster SSA operated in pulsed regime, some modifications were necessary for the three SSAs that will be delivered by ELTA for an operation in CW on the storage ring. In parallel, the ESRF is developing a more compact SSA using cavity combiners *) instead of the widely adopted coaxial combiner trees. The status of this R&D project will also be reported.

WEPFI005

Simulations and RF Measurements of the Fundamental and Higher Order Modes of the ThomX 500 MHz Cavity

HOM, impedance, feedback, controls

2711

M. El Khaldi, I.V. Drebot, P. Lepercq, R. Marie, B. Mercier, T. Roulet, A. Variola, F. Wicek
LAL, Orsay, France
H.D. Dias, M.D. Diop, M.E. El Ajjouri, R. Lopes, A. Loulergue, P. Marchand, F. Ribeiro, R. Sreedharan
SOLEIL, Gif-sur-Yvette, France

The RF system of the ThomX* storage ring consists in a 500 MHz single cell copper cavity of the ELETTRA type, powered with a 50 kW CW solid state amplifier, and the associated Low Level RF feedback and control loops. The low operating energy of 50 – 70 MeV makes the impedances of the cavity higher order modes (HOMs) particularly critical for the beam stability. Their parasitic effects on the beam can be cured by HOM frequency shifting techniques, based on a fine temperature tuning and a dedicated plunger. A typical cavity temperature stability of ± 0.05°C within a range from 35 up to 80 °C can be achieved by a precise control of its water cooling temperature. On the other hand, the tuning of the cavity fundamental mode is achieved by changing its axial length by means of a mechanical tuner. In order to insure a fine control of the HOM frequencies, a good knowledge of their characteristics is mandatory. The main parameters of the fundamental and of the HOMs up to 4 GHz have been calculated using the HFSS and CST MWS codes. Preliminary measurements results have been obtained and show a good agreement with the simulations.
* A.Variola, “The ThomX Project”, Proceedings of IPAC2011, San Sebastián, Spain

WEPFI006

Broad and Narrow Band Feedback Systems at ELSA

feedback, kicker, HOM, damping

2714

M. Schedler, F. Frommberger, P. Hänisch, W. Hillert, C. Reinsch
ELSA, Bonn, Germany

At the Electron Stretcher Facility ELSA of Bonn University, an upgrade of the maximum stored beam current from 20 mA to 200 mA is planned. The storage ring operates applying a fast energy ramp of 6 GeV/s from 1.2 GeV to 3.5 GeV. The intended upgrade is mainly limited due to the excitation of multibunch instabilities. As a countermeasure, we succesfully commissioned state-of-the-art bunch by bunch feedback systems in the longitudinal and the two transverse dimensions. In addition, a narrow band cavity based feedback system for damping the most harmful longitudinal multi bunch mode caused by a HOM of the accelerating cavities is under construction.

WEPFI007

Amplitude, Phase and Temperature Stabilization of the ELSA RF System

LLRF, controls, HOM, feedback

2717

D. Sauerland, W. Hillert, A. Roth, M. Schedler
ELSA, Bonn, Germany
D. Teytelman
Dimtel, San Jose, USA

In the stretcher ring of the accelerator facility ELSA electrons are accelerated to a maximum energy of 3.2 GeV applying a fast energy ramp of up to 6 GeV/s. In order to be able to offer higher external beam currents one has to increase the current of the internal beam in ELSA accordingly. The beam current is limited due to excitation of multi bunch instabilities which are mainly caused by higher order modes of the two PETRA cavities used for particle acceleration in the stretcher ring. To control the resonance frequency of these modes, a variable bypass of the cavities' cooling system has been installed which allows a stabilization of their temperature. With this modification, it is possible to vary the temperature of the cavities between 26 °C and 65 °C and thus to shift the higher order modes by hundreds of kHz in frequency. Additionally, first operational studies with a prototype of a FPGA based LLRF system (Dimtel) have been performed which in future will be used to stabilize the amplitude and phase of the accelerating RF fields of the cavities.

WEPFI009

RF Measurement during CW Operation of an RFQ Prototype

rfq, simulation, proton, linac

2720

M. Vossberg, H.C. Lenz, H. Podlech, A. Schempp
IAP, Frankfurt am Main, Germany
A. Bechtold
NTG Neue Technologien GmbH & Co KG, Gelnhausen, Germany

A 17 MeV MHz proton linac is being developed as a front end of the driver accelerator for the MYRRHA facility in Mol. As a part of the MAX (MYRRHA Accelerator Experiment and Development) project a 4-rod Test-RFQ with a resonance frequency of 176 MHz has been designed and built for the MAX-Project. The RFQ has been modified to solve the cooling problem at cw-operation, the geometrical precision had to be improved as well as the rf-contacts. The developments led to a new layout and a sophisticated production procedure of the stems and the electrodes. Calculations show an improved Rp-value leading to power losses less than 30 kW/m, which is about 60 % of the power losses which could be achieved safely at cw-operation of the similar Saraf-RFQ. Thermal measurements and simulations with the single components has been completed. During cw-operation the temperature distribution will be measured and the rf-performance checked.

WEPFI012

Conceptual Design of ILSF RF System

HOM, LLRF, storage-ring, impedance

2723

Kh.S. Sarhadi, H. Ajam, H. Azizi, M. Fereidani, M. Jafarzadeh, S. Pirani, J. Rahighi, R. Safian, A. Shahverdi
ILSF, Tehran, Iran

The Iranian Light Source Facility (ILSF) RF system, consisting of RF cavities, power sources and low-level RF systems, is conceptually designed in accordance with the requirements of ILSF 3GeV storage ring. To achieve the desired 400mA beam current, utilization of the existing HOM-damped cavities is explored and RF system parameters are compared based on the usage of each cavity. Moreover, the choice of solid state amplifier as the RF power source is presented with its available power and structure. This paper, furthermore, explains the conceptual design and functionality of the selected digital LLRF system.

WEPFI016

Upgrade of Power Supply System for RF-Chopper At J-PARC Linac

pick-up, linac, LLRF, simulation

2735

K. Futatsukawa, Z. Fang, Y. Fukui, M. Ikegami, T. Miyao
KEK, Ibaraki, Japan
E. Chishiro, K. Hirano, Y. Ito, N. Kikuzawa, A. Miura, F. Sato, S. Shinozaki
JAEA/J-PARC, Tokai-mura, Japan
T. Hori
JAEA, Ibaraki-ken, Japan
Y. Liu, T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
T. Suzuki
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan

In the J-PARC Linac, the radio frequency deflector was adopted as a chopper to capture the particles into the RF-bucket in the next synchrotron. The chopper, consists of two deflectors, was installed on the medium-energy beam-transport line. In the operation of the RF-chopper, the fast rise/fall time of the pulse is a fundamental requirement to minimize the beam loss due to insufficient deflection to some beam bunches. In the previous system, the two series-connected chopper deflectors were driven by one solid- state amplifier. However, the fall time indicated a poor result to effect the ringing into each cavity. Therefore, the additional solid-state amplifier and low level RF system were installed in the summer 2012 and the connection changed to the parallel system from the series using two amplifiers. The rise/fall time of the chopped beam, is defined as the step height of 10% and 90%, was about 20 nsec in the beam current of 15 mA and the effect of the ringing was decreased. We would like to introduce the performance of the new chopper system.

WEPFI017

Performance of Cavity Phase Monitor at J-PARC Linac

linac, pick-up, DTL, LLRF

2738

K. Futatsukawa, S. Anami, Z. Fang, Y. Fukui, T. Kobayashi, S. Michizono
KEK, Ibaraki, Japan
F. Sato, S. Shinozaki
JAEA/J-PARC, Tokai-mura, Japan

The amplitude and the phase stabilities of the RF system play an important role for the cavity of a high intensity proton accelerator. For the J-PARC Linac, the accelerating field ambiguity must be maintained within ±1% in amplitude and ±1 degree in phase due to the momentum acceptance of the next synchrotron. To realize the requirement, a digital feedback (FB) control is used in the low level RF (LLRF) control system, and a feed-forward (FF) technique is combined with the FB control for the beam loading compensation. The stability of ±0.2% in amplitude and ±0.2 degree in phase of the cavity was achieved including the beam loading in a macro pulse. Additionally, the cavity phase monitors, which can measure the phase difference between any two cavities, were installed in summer, 2011. The monitor has the three different types, which are for the present 324-MHz RF system, the 972-MHz RF system and the combined system of 324-MHz RF and 972-MHz RF. The phase monitor for the 324-MHz RF has been in operated since Dec. 2011. We would like to introduce the phase monitor and indicate the phase stability at the J-PARC linac.

WEPFI019

High Power Test of Kanthal-coated L-band Lossy Cavity

vacuum, positron, klystron, solenoid

2744

F. Miyahara, Y. Arakida, Y. Higashi, T. Higo, K. Kakihara, S. Matsumoto
KEK, Ibaraki, Japan
K. Saito
Hitachi, Ltd., Energy and Environmental System Laboratory, Hitachi-shi, Japan
H. Sakurabata
Hitachi, Ltd., Power & Industrial Systems R&D Laboratory, Ibaraki-ken, Japan

We have been developing a Kanthal (Al-Cr-Fe)-coated collinear load as a possible candidate of the L-band acc. structure of SuperKEKB positron capture system. In order to achieve the higher capture efficiency comparing to that of KEKB, the upgrade of the e⁺ production and capture section is required. The system consists of a W target with a flux concentrator followed by acc. structures surrounded by solenoids. The increase of the e⁺ bunch charge and the reduction of satellite bunches are the main issues for this system. The frequency choice of L-band is based on the larger transverse and longitudinal acceptances than those of the S-band one. The load is preferable to compose the system with compact magnets and to minimize the dip in the solenoid field. The design of the load was reported in previous work*. We understand that the Kanthal-coated cell should be confirmed in high power to confirm the feasibility at our design field of 10 MV/m level. We are making a test cavity which consists of 3 cells and one of them is composed of Kanthal-coated disks to lower the intrinsic Q value from 20000 to the order of 1000. The cavity production and the experimental result will be reported.
*Development of L-band accelerating structure with Kanthal-coated collinear load for SuperKEKB, IPAC12, THLR04.

WEPFI021

Influence of Core Winding Tension and Ribbon Quality on the MA Core RF Characteristics

impedance, synchrotron, vacuum, factory

2747

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

J-PARC 3 GeV Rapid Cycling Synchrotron (RCS) and Main Ring (MR) employ RF cavities loaded with Magnetic Alloy (MA) cores to generate a high field gradient. To achieve the high field gradient, the core shunt impedance is a key parameter. We found during the development of MA cores for RCS RF cavities that the core shunt impedance was increased by lowering a core winding tension. We lowered the core winding tension in order to improve the electrical insulation between MA ribbon layers. The lower winding tension reduced the core filling factor that is defined as the volume ratio of MA ribbons and geometrical dimensions. The core shunt impedance might be reduced according to the core filling factor reduction. We discuss the reason why the lower winding tension increased the core shunt impedance. We also report the influence of the ribbon quality variation on the MA core RF characteristics.

WEPFI022

Inner Diameter Change over the Years of MA Cores of RF-cavities at the J-PARC 3 GeV Synchrotron

synchrotron, gun

2750

T. Shimada, M. Nomura, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan
K. Hara, K. Hasegawa, C. Ohmori, M. Toda, M. Yoshii
KEK, Tokai, Ibaraki, Japan
A. Schnase
GSI, Darmstadt, Germany
H. Suzuki
Japan Atomic Energy Agency (JAEA), International Fusion Energy Research Center (IFERC), Rokkasho, Kamikita, Aomori, Japan

The 11 RF cavities at the J-PARC 3 GeV synchrotron use 198 MA cores. Buckling occurred in some cores since the operation started in October 2007. We have measured the inner diameters of the cores as part of the investigation to determine the cause of buckling when the cavities were disassembled for maintenance. We obtained inner diameter change values of 36 cores over a longer than 2 years interval in the summer of 2012. We noticed deformations of the inner shapes of the cores related to the manufacturing process, and that inner diameter changes over this period were not detected in most of the cores without buckling. Furthermore, an effective core manufacturing process to avoid the buckling has been established. We are going to replace old type cores with new type cores in summer shutdown periods every year and will have finished the replacement work by the summer of 2013. We report the relation between inner shapes of the cores and the manufacturing process and inner shape changes over the years.

WEPFI023

Study on Two-cell RF-deflector Cavity for Ultra-short Electron Bunch Measurement

electron, gun, simulation, target

2753

Y. Nishimura, K. Sakaue, T. Takahashi, M. Washio
Waseda University, Tokyo, Japan
T. Takatomi, J. Urakawa
KEK, Ibaraki, Japan

Funding: Work supported by JSPS Grant-in-Aid for Scientific Research (A) 10001690 and the Quantum Beam Technology Program of MEXT.
We have been developing an S-band Cs-Te photocathode rf electron gun system for pulse radiolysis and laser Compton scattering experiment at Waseda University. These researches demand for high quality and well controlled electron beam. In order to measure the ultra-short electron bunch, we decided to use rf-deflector cavity, which can convert the longitudinal distribution to that of transverse. With this technique, the longitudinal bunch profile can be obtained as the transverse profile. We used the 3D electromagnetic simulation codes HFSS for designing rf deflector cavity and GPT for beam tracking. The cavity has 2 cell structures operating on π mode, standing wave, dipole (TM120) mode at 2856MHz. We have confirmed on HFSS that 2 cell rf-deflector cavity can produce 660G magnetic field per cell on beam line with 750kW input rf power. This field strength is enough for our target, which is 100fs bunch length measurement at 4.3MeV. In this conference, we will present the cavity structure design, the present progresses and future plan.

WEPFI026

Design and Commissioning of the RF System of CYCIAE 14 Cyclotron

cyclotron, controls, low-level-rf, resonance

2759

Z.G. Yin, B. Ji, Y. Lei, P.Z. Li, G.F. Song, C. Wang, T.J. Zhang, Z.L. Zhao
CIAE, Beijing, People's Republic of China

The RF system of CYCIAE-14 consists of a set of 20kW amplifier, two 1/4λ RF cavities connected in central region, the transmission line and a set of LLRF system. The LLRF system, based on DDS and DSP, has achieved the close-loop adjustment of accelerating voltage and the resonant frequency. The RF system design for CYCIAE-14 was started in 2010, and the fabrication of the major equipments was finished in 2011. The installation and commissioning was completed in early 2012, satisfying the design requirements. This article describes the design of the RF system, and summarizes the difficulties encountered in the process of manufacture, installation and commissioning. Some of the problems caused by the transmission line and the RF leakage are analyzed, followed by the measures taken to solve these problems.

WEPFI027

The Measurement of the Ferrite Rings for the Mass Production RF Cavity of CSNS RCS

impedance, LLRF, resonance, booster

2762

H. Shi, W.L. Huang, B. Jiang, X. Li, W. Long, W.Y. Song, H. Sun, J.Y. Tang, C.L. Xie, C.L. Zhang, W. Zhang
IHEP, Beijing, People's Republic of China

The Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) will install 8 ferrite-loaded coaxial resonant cavities. The construction and measurement of prototype cavity have been finished. Based on the existing experiences, the small inner diameter (ID) rings T500/250/25-4M2 (mm) have been adopted for the mass production RF cavity, and the test results have shown that such rings can bear more RF magnetic flux density and have lower power loss. The characteristics of 60 small ID rings have been measured with two-ring test system, and we figured out that the rings have good consistence and the shunt impedance of all rings is above 100 Ω.

WEPFI028

RF System of the CSNS Synchrotron

controls, LLRF, feedback, synchrotron

2765

H. Sun, W.L. Huang, X. Li, W. Long, H. Shi, C.L. Zhang, F.C. Zhao
IHEP, Beijing, People's Republic of China

The accelerator of China Spallation Neutron Source (CSNS) consists of a H− linac and a rapid cycling synchrotron (RCS). The protons injected into the RCS will be accelerated from 81MeV to 1.6GeV by the Ring RF system providing a maximum accelerating voltage of 165kV. The RF frequency sweeps from 1.02 MHz to 2.44 MHz. with a repetition rate of 25Hz. The ferrite-loaded RF cavities will be used in the ring RF system. Each cavity has own RF power tube amplifier, bias current supply and full digital LLRF control loops. The R&D of ring rf system have been completed, it compose of the prototypes of a full size ferrite loaded RF cavity, a high power tetrode amplifier, a switching type bias supply of 3000A and a full digital embedded controller of LLRF. CSNS ring RF system design and the results of the R&D will be described in this paper.

WEPFI031

Development of an X-Band Metallic Power Extractor for the Argonne Wakefield Accelerator

damping, impedance, extraction, simulation

2771

J. Shi, H.B. Chen, Q. Gao, X.W. Wu, Y. Yang, H. Zha
TUB, Beijing, People's Republic of China
W. Gai, C.-J. Jing
ANL, Argonne, USA

An X-band (11.7GHz) power extractor has been developed for RF power generation at Argonne Wakefield Accelerator (AWA). The structure is a 2pi/3-mode disk-loaded structure with group velocity of 22% of the speed of light and a total length of about 300mm. It is build with copper disks brazed together. This note presents the design and the fabrication of this structure, as well as the RF measurement results.

WEPFI032

New Calibration Method for Radial Line Experiment

wakefield, collider, damping, linear-collider

2774

X.W. Wu, H.B. Chen, J. Shi, H. Zha
TUB, Beijing, People's Republic of China

A radial line experiment is proposed to test the SiC load disks of the choke-mode structure. However, the general calibration cannot work out in this situation due to lack of matched load. A new calibration method named multi-offset short calibration is proposed. The principles of the method and the calibration steps involved are presented and the results of actual experimentation are used to validate the method. The results show multi-offset short calibration is a feasible method and that this method can provide a viable calibration scheme for radial line measurements.

WEPFI038

R&D of New C-band Accelerating Structure for SXFEL Facility

FEL, impedance, wakefield, linac

2785

W. Fang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
L. Chen, X. Sheng
BVERI, Beijing, People's Republic of China
D.C. Tong
TUB, Beijing, People's Republic of China

C-band high gradient accelerating structure is crucial technology for Shanghai Soft X-ray FEL facility. Based on the prototype, the optimized C-band accelerating structure is proposed, and the experimental model is ready for high power test. In this paper, optimization design and some experiment results are presented, also design, fabrication and cold test of experimental model are introduced.

WEPFI039

New X-band Deflecting Cavity Design for Ultra-short Bunch Length Measure of FEL at SINAP

simulation, electron, impedance, FEL

2788

J.H. Tan, W. Fang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

For the development of Free Electron Lasers (FEL) at SINAP, ultra-short bunch is the crucial requirement for excellent lasing performance. It’s big challenge for deflecting cavity to measure the length of ultra-short bunch, and higher deflecting gradient is required for higher measurement resolution. X-band travelling wave deflecting structure has features of higher deflecting voltage and compact structure, which is good performance at ultra-short bunch length measuring. In this paper, a new X-band deflecting structure was designed, operated at HEM11- 2π/3 mode. For suppressing the polarization of deflection plane of the HEM11 mode, two symmetrical caves are added on the cavity wall to separate two polarized modes. More details of design and simulation results are presented in this paper.

WEPFI040

R&D of C-band Pulse Compression for Soft X-ray FEL at SINAP

coupling, simulation, FEL, klystron

2791

C.P. Wang, W. Fang, Q. Gu, W.C. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

A compact Soft X-ray Free Electron Lasers facility is presently being constructed at SINAP, and 8 C-band accelerating structure unit are required for third-stage including 4 pulse compressors. The field mode of C-band SLED is TE0.1.15 with high quality factor Q, and the coupling coefficient is 8.5. Based on the design, the power pulse of klystron is compressed from 2.5μs to 0.5μs, and finally the power gain is about 3.1. In this paper, the details and simulation of 3-dB coupler, mode convertors and the resonant cavities are presented, meanwhile some cold test results of cavity are also analyzed at the end of this paper.

WEPFI041

Design of the RF System for the Accelerator Complex of Rare Isotope Science Project

LLRF, rfq, controls, rf-amplifier

2794

J. Han, O.R. Choi, J.-W. Kim
IBS, Daejeon, Republic of Korea
C.K. Hwang
KAERI, Daejon, Republic of Korea

The rare isotope beam facility planned in Korea utilizes superconducting linear accelerators and a cyclotron to accelerate heavy-ion and proton beams, in which an RFQ in the injection line and superconducting cavities are the main rf components. The RF systems to power the cavities and to control the system at the low level have been designed so as to acquire high-quality beam with precise controls of rf amplitude and phase. The superconducting cavity is sensitive to various perturbations like mechanical vibration and Lorentz force detuning due to narrow bandwidth. We plan to use the rf amplifier system based on solid state device for superconducting cavities, and a tetrode tube for the final stage of RF amplifier of the RFQ accelerator. An LLRF system to control the amplitude and phase, which was built and tested on a quarter-wave resonator, will be modified to control a superconducting cavity. We plan to test the LLRF system in the superconducting rf facility abroad.

WEPFI044

High Power Test of New SLED System with Biplanar 3-dB Power Divider and Dual Side-wall Coupling Irises for PAL XFEL

coupling, klystron, simulation, free-electron-laser

2803

Y.D. Joo, H. Heo, W.H. Hwang, H.-S. Lee, K.M. Oh, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

The new type of the Stanford Linear Accelerator Energy Doubler (SLED) system for the PAL (Pohang Accelerator Laboratory) XFEL (X-ray Free Electron Laser) is developed to be operated with an RF input power of 80 MW and a pulse width of 4 μs. To prevent the RF breakdown such a high power operation, a biplanar 3-dB power divider and dual side-wall coupling irises structure are used in the new SELD system. It is shown that the field gradient and surface current is reduced from that of the original SLED system using the the finite-difference time-domain (FDTD) simulation. The high power test result of the new SLED system in the PAL XFEL test facility will be presented.

WEPFI049

CoStub: A 6 1/8” Coaxial Short Circuit using Stubs

simulation, background, synchrotron, high-voltage

2809

B. Bravo, F. Mares, F. Pérez
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

ALBA is a 3Gev synchrotron light source located in Barcelona and operating with users since May 2012. The ALBA storage ring uses six room temperature cavities; each one fed by two 80kW IOTs amplifiers at 499.654 MHz. The power of the pair of transmitters is combined by a cavity combiner, CaCo. The two possible operation modes of CaCo at high power have been tested. The symmetrical mode (two IOTs feed the CaCo symmetrically) works properly and without presenting any problem. But in the asymmetrical mode (one IOT feeds the CaCo and the other is keeping passive) a standing wave is created between the passive IOT and Caco, provoking a large voltage in the gap of the passive IOT that broke the ceramic. A new device, CoStub (coaxial stub), to short circuit the coaxial waveguide of the passive arm and protects the passive IOT has been built and successfully tested. This paper presents the design details and the low level and high power test of this device.

WEPFI054

Enlargement of Tuning Range in a Ferrite-tuned Cavity through Superposed Orthogonal and Parallel Magnetic Bias

factory, resonance, radiation

2812

C. Vollinger, F. Caspers
CERN, Geneva, Switzerland

Conventional ferrite-tuned cavities operate either with bias fields that are orthogonal or parallel to the magnetic RF-field. For a cavity that tunes rapidly over an overall frequency range around 100-400 MHz with high Q, we use ferrite garnets exposed to an innovative new biasing method consisting of a superposition of perpendicular and parallel magnetic fields. This method leads to a significant enlargement of the high-Q cavity tuning range by defining an operation point close to the magnetic saturation and thus improving ferrite material behaviour. A further advantage of this technique is the fast tuning speed resulting from the fact that tuning is carried out either with pure parallel biasing, or together with a very small change of operating point from perpendicular bias. In this paper, several scaled test models of ferrite-filled resonators are shown; measurements on the set-ups are compared and discussed.

WEPFI059

C-band RF Pulse Compressor for SwissFEL

coupling, resonance, HOM, klystron

2827

R. Zennaro, M. Bopp, A. Citterio, R. Reiser, T. Stapf
PSI, Villigen PSI, Switzerland

The SwissFEL C-band (5.712 GHz) linac consists of 28 RF modules. Each module is composed of a single 50 MW klystron feeding a pulse compressor and four two meter long accelerating structures. The pulse compressor is based on a single Barrel Open Cavity (BOC). The BOC makes use of a “whispering gallery” mode which has an intrinsically high quality factor and operates in resonant rotating wave regime; moreover, and contrary to the conventional SLED scheme, a single cavity is sufficient to define the pulse compressor, without the need for two cavities and a 3-dB hybrid. A prototype has been manufactured and successfully tested. A short description of the BOC is presented, together with the prototype design, production, low level RF measurements, and high power test.

WEPFI061

Petra Cavity Vacuum RF Condition with Field Balance Mechanism for TPS Storage Ring in NSRRC

coupling, vacuum, controls, storage-ring

2833

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

In the first stage commissioning of TPS (Taiwan Photon source) storage ring in NSRRC, two room temperature Petra cavities will be used. At this commission stage, 100mA with 950keV beam loss is estimated to have 47.5kW beam loss for each cavity. In the meanwhile, the cavity loss at the specified 1.2MV of each cavity will be about 50kW. Therefore, coupling coefficient of 2 is required. However, the initial design specification of Petra cavity has only beta of about 1.7. Hence, the modification of the input coupler is done with the enhancement of its beta as well as advanced water cooling for some heat point. Besides, due to the two-tuner system of Petra cavity, special field-balance tuner control system is also developed. In RF condition for better vacuum up to 1.4MV, some modification of the tuner mechanical structure is also done to reach high vacuum condition (lower than 5*10^-9 Torr) for storage ring requirement.

WEPFI062

Precise Cavity Tuning System of a Low Output-impedance Second-harmonic Cavity at ISIS

impedance, resonance, cathode, beam-loading

2836

Y. Irie, S. Fukumoto, K. Muto, H. Nakanishi
KEK, Ibaraki, Japan
D.B. Allen, D. Bayley, N.E. Farthing, 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, M.E. Middendorf
ANL, Argonne, USA

A very low output-impedance (~35ohms) second-harmonic cavity system is being developed for high intensity proton accelerators. The final amplifier is comprised of a grounded cathode scheme with a feedback loop from anode to grid. Due to the Miller effect, the grid voltage waveform is seriously distorted even if only a few percent of sub-harmonic or higher harmonic are mixed in the generator current. Such distortion is much enhanced by the beam loading. In order to eliminate the effect of this distortion upon the phase detector used to achieve precise cavity tuning, a swept bandpass filter was applied to the grid voltage at the phase detector input. Filter design details and the result of high power tests are reported.

WEPFI063

Progress on the ISIS Synchrotron Low Power RF System Upgrade

controls, synchrotron, acceleration, proton

2839

A. Seville, D.B. Allen, D. Bayley, N.E. Farthing, I.S.K. Gardner, R.J. Mathieson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
W.L. Huang
IHEP, Beijing, People's Republic of China

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 operate two target stations simultaneously. To give more stable control 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. A new FPGA based master oscillator has been implemented using a National Instruments FlexRIO module. The replacement master oscillator has been tested with beam for the first time. This paper reports on the tests of the FlexRIO master oscillator and describes plans for the gradual replacement of the remaining parts of the LPRF system.

WEPFI064

Prototype Refinement of the VELA Transverse Deflecting Cavity Design

simulation, target, vacuum, emittance

2842

P. Goudket, S.R. Buckley, L.S. Cowie, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

The Versatile Linear Accelerator (VELA) at Daresbury Laboratory will deliver low energy (5/6 MeV) short bunches (~40 fs) to a number of industrial experimental stations and for scientific research. In order to measure the longitudinal profile of the bunch an S-band transverse deflecting cavity will be inserted into the beamline. A transverse kick of around 5 MV is required therefore a 9 cell design has been chosen. As part of the design iteration a three-cell prototype has been built. Frequency measurements have been performed on the prototype cavity as well as Coordinate Measuring Machine to confirm that the dimensions are to the required design tolerances. Subsequently, further modelling has been performed to improve and refine the design of the 9-cell cavity, to ensure that the frequency of the final design is within the tuning range of the water thermal control system and that the field flatness requirement can be obtained.

WEPFI065

The Commissioning of the EBTF S-band Photoinjector Gun at Daresbury Laboratory

klystron, electron, vacuum, laser

2845

A.E. Wheelhouse, R.K. Buckley, S.R. Buckley, P.A. Corlett, J.W. McKenzie, B.L. Militsyn, A.J. Moss
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The first stage of the installation of the Electron Beam Test Facility (EBTF) at Daresbury Laboratory has been completed and a commissioning phase is presently underway. At the heart of the machine is a photoinjector based on a two and a half cell S-band RF gun incorporating a metallic photocathode, which is capable of delivering 4-6 MeV, low emittance, short electron pulses (10 - 250 pC). The photoinjector is driven by a UV light at 266 nm wavelength delivered by a laser system and is powered by a RF system incorporating a Low Level RF system, a high power RF modulator and a klystron. This paper describes the commissioning and conditioning of the photoinjector.

WEPFI066

The RF System for the MICE Experiment

controls, LLRF, diagnostics, linac

2848

K. Ronald, A.J. Dick, C.G. Whyte
USTRAT/SUPA, Glasgow, United Kingdom
P.A. Corlett
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A.J. DeMello, D. Li, S.P. Virostek
LBNL, Berkeley, California, USA
A.F. Grant, A.J. Moss, C.J. White
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
P.M. Hanlet
IIT, Chicago, Illinois, USA
C. Hunt, K.R. Long, J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
A. Moretti, R.J. Pasquinelli, D.W. Peterson, R.P. Schultz, J.T. Volk
Fermilab, Batavia, USA
P.J. Smith
Sheffield University, Sheffield, United Kingdom
T. Stanley
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
Y. Torun
Illinois Institute of Technology, Chicago, IL, USA

The International Muon Ionisation Cooling Experiment (MICE) is designed to demonstrate the effectiveness of ionisation cooling to reduce the phase space footprint of a muon beam, principally to allow the subsequent acceleration of muons for next generation colliders and/or neutrino factories. The experiment (and indeed any subsequent accelerator cooling channel based on the same principles) poses certain unusual requirements on its RF system, whilst the precision measurement of the ionisation cooling process demands special diagnostics. This paper shall outline the key features of the RF system, including the LLRF control, the power amplifier chain, distribution network, cavities, tuners and couplers, all of which must operate in a high magnetic field environment. The RF diagnostics which, in conjunction with the other MICE diagnostics, shall allow detailed knowledge of the amplitude and phase of the acceleration field during the transit of each individual Muon shall also be outlined.

WEPFI070

Design of RFQ Coupler for PXIE Project

rfq, simulation, coupling, ion

2854

S. Kazakov, T.N. Khabiboulline, V. Poloubotko, O. Pronitchev, V.P. Yakovlev
Fermilab, Batavia, USA

Design of new coupler for PXIE RFQ is reported. Two couplers are supposed to deliver ~ 100 kW total CW RF power to RFQ at 162.5 MHz. Coupler has a magnetic loop coupling with the RFQ. Nevertheless it allows to apply a HV bias to suppress a multipactor due to original design of the coupling loop. Results of RF, multipactor and thermal simulations are presented.

WEPFI072

Analysis of Breakdown Damage in an 805 MHz Pillbox Cavity for Muon Ionization Cooling R&D

site, cathode, plasma, radiation

2857

D.L. Bowring, D. Li
LBNL, Berkeley, California, USA
A. Moretti, Y. Torun
Fermilab, Batavia, USA

When operating in multi-Tesla solenoidal magnetic fields, normal-conducting cavities exhibit RF breakdown at anomalously low gradients. This breakdown behavior may be due to field-emitted electrons, focused by the magnetic field into "beamlets" with relatively large current densities. These beamlets may then cause pulsed heating and cyclic fatigue damage on cavity interior surfaces. If this model is correct, materials with long radiation lengths (relative to copper) may alleviate the problem of RF breakdown in strong magnetic fields. To study this phenomenon, RF breakdown was induced on pairs of "buttons" in an 805 MHz pillbox cavity. The shape of the buttons creates a local enhancement of the surface electric field, such that breakdown occurs preferentially on the button surface. Beryllium and copper buttons were tested in order to evaluate the effect of radiation length on RF breakdown performance. This poster presents an analysis of the damage to these buttons and suggests a path forward for future materials R&D related to breakdown in strong magnetic fields.

WEPFI073

A Modular Cavity for Muon Ionization Cooling R&D

simulation, coupling, vacuum, solenoid

2860

D.L. Bowring, A.J. DeMello, A.R. Lambert, D. Li, S.P. Virostek, M.S. Zisman
LBNL, Berkeley, California, USA
C. Adolphsen, L. Ge, A.A. Haase, K.H. Lee, Z. Li, D.W. Martin
SLAC, Menlo Park, California, USA
D.M. Kaplan
Illinois Institute of Technology, Chicago, Illinois, USA
T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
A. Moretti, M.A. Palmer, R.J. Pasquinelli, Y. Torun
Fermilab, Batavia, USA
R.B. Palmer
BNL, Upton, Long Island, New York, USA

The Muon Accelerator Program (MAP) collaboration is developing an ionization cooling channel for muon beams. Ionization cooling channel designs call for the operation of high-gradient, normal-conducting RF cavities in multi-Tesla solenoidal magnetic fields. However, strong magnetic fields have been shown to limit the maximum achievable gradient in RF cavities. This gradient limit is characterized by RF breakdown and damage to the cavity surface. To study this issue, we have developed an experimental program based on a modular pillbox cavity operating at 805 MHz. The modular cavity design allows for the evaluation of different cavity materials - such as beryllium - which may ameliorate or circumvent RF breakdown triggers. Modular cavity components may furthermore be prepared with different surface treatments, such as high-temperature baking or chemical polishing. This poster presents the design and experimental status of the modular cavity, as well as future plans for the experimental program.

WEPFI074

RF Cavity Spark Localization Using Acoustic Measurement

diagnostics, background, LabView, collider

2863

P. Snopok
IIT, Chicago, Illinois, USA
A.D. Bross
Fermilab, Batavia, USA
P.G. Lane, Y. Torun
Illinois Institute of Technology, Chicago, Illinois, USA

Current designs for muon cooling channels require high-gradient RF cavities to be placed in solenoidal magnetic fields in order to contain muons with large transverse emittances. It has been found that doing so reduces the threshold at which RF cavity breakdown occurs. To aid the effort to study RF cavity breakdown in magnetic fields it would be helpful to have a diagnostic tool which can detect breakdown and localize the source of the breakdown inside the cavity. We report here on progress towards developing a diagnostic tool for detecting and localizing sparks in an RF cavity by using piezoelectric transducers.

WEPFI079

Electromagnetic Modeling of RF Drive in the LANSCE DTL

coupling, DTL, simulation, HOM

2878

S.S. Kurennoy
LANL, Los Alamos, New Mexico, USA

A 3D electromagnetic model of the RF drive module in the LANSCE DTL tank 4 has been developed with the CST MicroWave Studio. The model is explored both with eigensolver and in time domain to evaluate maximal fields in the drive module and RF coupling. Here we describe the model and present simulation results.

WEPFI080

Waveguide Component R&D for the ILC

klystron, linac, coupling, linear-collider

2881

C.D. Nantista, C. Adolphsen, G.B. Bowden, A.A. Haase, B.D. McKee, F.Y. Wang
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.
Several years of effort have gone into refining the design of the International Linear Collider. The direction the design has evolved in response to driving considerations has resulted in a more sophisticated waveguide system for delivering RF power to the cavities. In particular, the desire to eliminate parallel service tunnels along the main linacs led to the proposal of the Klystron Cluster Scheme (KCS)*, involving plumbing the combined power from groups of klystrons down from the surface at several locations in overmoded waveguide. Additionally, to increase superconducting cavity yield, the acceptance criteria were relaxed to encompass a ±20% range in sustainable operating gradient, which must be accommodated by tailoring of the RF power distribution. Designs and prototype testing of some of the novel waveguide components developed to allow these changes are described here.
* Christopher Nantista and Chris Adolphsen, “Klystron Cluster Scheme for ILC High Power RF Distribution,” presented at the 2009 Particle Accel. Conf., Vancouver, B.C., Canada, May 2009.

WEPFI082

Double-tip Magnetic Field Enhancement

simulation, vacuum, electron, cathode

2887

F.Y. Wang, L. Xiao
SLAC, Menlo Park, California, USA

The local electric field enhancement factor β in an rf accelerator cavity has been studied experimentally for decades and found to be in the range from few tens up to few hundreds for various rf frequencies and materials. A large field enhancement factor is usually thought to come from sharp tips whose β is roughly the ratio of their height to their tip radius. For a β of few hundred, the corresponding tip height would need to be more than 10 microns, which should be visible in a scanning electron microscope (SEM). However, the estimated β from SEM images of cavity surfaces is around 10. Therefore, the physics of such large β values is still not clear. In this paper, we have studied differentμstructures and found that the magnetic field could be enhanced many times in the presence of two nearby tips with β of 10. The large local magnetic field enhancement could lead to large enhanced pulsed heating and thus could melt surface in a very short time and form a liquid Taylor cone.

WEPFI085

Source and Extraction for Simultaneous Four-hall Beam Delivery System at CEBAF

laser, extraction, cathode, electron

2896

R. Kazimi, J. Hansknecht, M. Spata, H. Wang
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A new design for simultaneous delivery of the electron beam to all four 12 GeV CEBAF experimental halls* requires a new 750 MHz RF separator system in the 5th pass extraction region, a 250 MHz repetition rate for its beams, and addition of a fourth laser at the photo-cathode gun. The proposed system works in tandem with the existing 500 MHz RF separators and beam repetition rate on the lower passes. The new 5th pass RF separators will have the same basic design but modified to run at 750 MHz. The change to the beam repetition rate will be at the photo-cathode gun through an innovative upgrade of the seed laser driver system using electro-optic modulators. The new laser system also allows addition of the fourth laser. The new RF separators, the new laser system and other hardware changes required to implement the Four-Hall operation delivery system will be discussed in this paper.
* Simultaneous Four-Hall Operation for 12 GeV CEBAF, Proceedings of this conference.

WEPFI086

Normal Conducting Radio Frequency X-band Deflecting Cavity Fabrication, Validation and Tuning

electron, vacuum, linear-collider, collider

2899

R.B. Agustsson, L. Faillace, A.Y. Murokh, E. Spranza, S. Storms
RadiaBeam, Santa Monica, USA
D. Alesini
INFN/LNF, Frascati (Roma), Italy
V.A. Dolgashev, J.R. Lewandowski
SLAC, Menlo Park, California, USA
J.B. Rosenzweig
UCLA, Los Angeles, California, USA
V. Yakimenko
BNL, Upton, Long Island, New York, USA

An X-band Traveling wave Deflector mode cavity (XTD) has been developed, fabricated, tuned and characterized by Radiabeam Technologies to perform longitudinal measurement of the sub-picosecond ultra-relativistic electron beams. The device is optimized for the 100 MeV electron beam parameters at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory, and is scalable to higher energies. The XTD is designed to operate at 11.424 GHz, and features short filling time, femtosecond resolution, and a small footprint. RF design, structure fabrication, cold testing and tuning results are presented.

WEPFI091

Design of a Normal-conducting RF-dipole Deflecting Cavity

dipole, simulation, luminosity, extraction

2911

T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
D. Li
LBNL, Berkeley, California, USA

In this paper we present a novel design of a CW normal conducting RF deflecting cavity. The cavity is designed into a dipole-like structure, resulting a high (R/Q)_transverse. The geometry at high H field is optimized to lower the surface peak power. We will show the design of a 325 MHz and 163 MHz cavity based on this structure and compare their performances with their superconducting counterparts.

WEPFI092

Multipacting Simulation of the MICE 201 MHz RF Cavity

solenoid, electron, simulation, coupling

2914

T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
D.L. Bowring, A.J. DeMello, D. Li, P. Pan, S.P. Virostek
LBNL, Berkeley, California, USA
L. Ge
SLAC, Menlo Park, California, USA

The international Muon Ionization Cooling Experiment (MICE) aims to demonstrate transverse cooling of muon beams by ionization. The MICE ionization cooling channel requires eight 201-MHz normal conducting RF cavities to compensate for the longitudinal beam energy loss in the cooling channel. Multipacting is a resonant electron discharge produced by the synchronization of emitted electrons with the RF fields, which can cause breakdown at high power RF operation. In this paper, we present the study of the multipacting effect in the MICE 201 MHz cavities with the SLAC ACE3P code. The simulation is carried out in the cavity body, the RF coupler region, and the coaxial waveguide, with the external magnetic field from the Coupling Coil. We will identify potential RF breakdowns due to multipacting and propose a solution to suppress them.

WEPME004

A Digital Beam-Phase Control System for a Heavy-Ion Synchrotron with a Double-Harmonic Cavity System

controls, synchrotron, feedback, dipole

2926

J. Grieser, D.E.M. Lens
TU Darmstadt, RTR, Darmstadt, Germany
U. Hartel
TEMF, TU Darmstadt, Darmstadt, Germany
H. Klingbeil, U. Laier, K.-P. Ningel, S. Schäfer, B. Zipfel
GSI, Darmstadt, Germany

Funding: Funded by GSI Helmholtzzentrum für Schwerionenforschung GmbH
For the new Facility for Antiproton and Ion Research (FAIR) at GSI Helmholtzzentrum für Schwerionenforschung GmbH, the heavy-ion synchrotron SIS18 will be operated with a double-harmonic cavity system*. The second cavity, running at twice the fundamental RF frequency, is used to lengthen the bucket which introduces nonlinearities to the control system. To damp longitudinal rigid dipole oscillations a digital feedback system consisting of a filter and an integrator is used. For the existing single-harmonic setup an FIR-filter is implemented which realizes a multiple bandpass filter with the first passband close to the synchrotron frequency. Both, the feedback gain and the passband frequency of the filter depend on the actual value of the synchrotron frequency**. It was shown by simulations and in an experiment that this setup can be transferred to a double-harmonic cavity system obtaining similar results for the region of stable feedback parameters, if the oscillation frequency of the bunch barycenter*** is considered instead of the synchrotron frequency of a linearized bucket. In this contribution the results of the simulation and the experiment are presented and compared.
*Klingbeil et al.: Phys. Rev. Special Topics - Accelerators and Beams 14, 102802, 2011
**Klingbeil et al.: IEEE Trans. on Nucl. Science, Vol. 54, No. 6, 2007
***Grieser et al.: Proc. 3rd IPAC, 2012

WEPME005

Pulsed RF Control for the P-Linac Test Stand at FAIR

controls, linac, proton, antiproton

2929

P. Nonn, U. Bonnes, C. Burandt, F. Hug, M. Konrad, N. Pietralla
TU Darmstadt, Darmstadt, Germany
R. Eichhorn
Cornell University, Ithaca, New York, USA
H. Klingbeil, G. Schreiber, W. Vinzenz
GSI, Darmstadt, Germany
H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Supported through BMBF contract no. 06DA9024I
The p-linac will be a dedicated proton injector for antiproton production at FAIR (GSI Darmstadt). It will provide a 70 MeV/70 mA pulsed proton beam with a duty cycle of about 10^-4. Therefore the RF of the normal conducting, coupled CH cavities* will be pulsed, too. In order to test the operation of those cavities, a test stand is under construction at GSI. The RF control hard- and software for the test stand is developed at TU Darmstadt. It is based on the digital low level RF control system, which is operational at the S-DALINAC**. Hardware as well as software had to be customized, in order to achieve pulsed operation within the given limits. These customizations as well as measurements from pulsed operation will be presented.
*R. Brodhage et al. Development and Measurements on a Coupled CH Proton Linac for FAIR, IPAC'10
**M. Konrad et al. Digital base band rf control system for the… , PRL ST Accel. & Beams 15

WEPME007

Commissioning of the Upgraded Superconducting CW Linac ELBE

klystron, vacuum, linac, SRF

2935

H. Büttig, A. Arnold, A. Büchner, M. Justus, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig, G.S. Staats, J. Teichert
HZDR, Dresden, Germany

With the expansion of the radiation source ELBE a center for high power radiation sources is being built at the Helmholtz Zentrum Dresden-Rossendorf (HZDR). In a first step (January 2012) the available CW RF-power (1.3 GHz) per superconducting 9-cell TESLA cavity at ELBE had been increased from 8.5 kW to 20 kW (CW) using solid state amplifiers. In a second step the performance of several machine components of ELBE must be redesigned to enable full power operation without risks. The poster gives an overview how these problems have been solved at ELBE and reports on the commissioning.

WEPME009

Recent Developments of the European XFEL LLRF System

LLRF, controls, laser, beam-loading

2941

Ch. Schmidt, G. Ayvazyan, V. Ayvazyan, J. Branlard, L. Butkowski, M.K. Grecki, M. Hoffmann, T. Jeżyński, F. Ludwig, U. Mavrič, S. Pfeiffer, H. Schlarb, H.C. Weddig, B.Y. Yang
DESY, Hamburg, Germany
P. Barmuta, S. Bou Habib, K. Czuba, M. Grzegrzółka, E. Janas, J. Piekarski, I. Rutkowski, D. Sikora, L. Zembala, M. Żukociński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
W. Cichalewski, K. Gnidzińska, W. Jałmużna, D.R. Makowski, A. Mielczarek, A. Napieralski, P. Perek, A. Piotrowski, T. Pożniak, K.P. Przygoda
TUL-DMCS, Łódź, Poland
S. Korolczuk, I.M. Kudla, J. Szewiński
NCBJ, Świerk/Otwock, Poland
K. Oliwa, W. Wierba
IFJ-PAN, Kraków, Poland

The European XFEL is comprised of more than 800 TESLA-type super-conducting accelerator cavities which are driven by 25 high-power multi-beam klystrons. For reliable, reproducible and maintainable operation of linac, the LLRF system will process more than 3000 RF channels. Beside the large number of RF channels to be processed, stable FEL operation demands field stability better than 0.010deg in phase and 0.01% in amplitude. To cope with these challenges the LLRF system is developed on MTCA.4 platform. In this paper, we will give an update of the latest electronics developments, advances in the feedback controller algorithm and measurement results at FLASH.

WEPME013

Development and Test of a Fully Automated PkQl Control Procedure at KEK STF

controls, LLRF, feedback, klystron

2950

M. Omet, A. Kuramoto
Sokendai, Ibaraki, Japan
H. Hayano, T. Matsumoto, S. Michizono
KEK, Ibaraki, Japan

In order to operate the cavities near their maximum gradients, cavity input (Pk) and cavity loaded Q (QL) should be controlled individually (PkQL control) at the International Linear Collider (ILC). A manual PkQL operation procedure was developed and performed at the linear electron accelerator at the Superconducting RF Test Facility (STF), in which the beam is accelerated up to 40 MeV by two superconducting 9-cell TESLA type L band cavities. The cavity gradients were set to 16 MV/m and 24 MV/m with QL values of 110⁶ and 3·10⁶. A 6.2 mA beam with a pulse length of 154 us was used. The field stabilities in amplitude were 0.160% and 0.097% for the cavities and 0.016% for the vector sum. The stabilities without beam are 0.057% and 0.054% for the cavities and 0.009% for the vector sum. For stability improvement during beam transient an adaptive beam feedforward for beam loading compensation is under development. So far an amplitude field stability of 0.013% for the vector sum was achieved at cavity gradients of 15 MV/m and 25 MV/m (no PkQL control) during a 6.8 mA beam with a pulse length of 123 us. Furthermore a fully automated PkQL control procedure is currently developed and tested.

Poster WEPME013 [0.647 MB]

WEPME014

Progress in Development of New LLRF Control System for SuperKEKB

controls, klystron, LLRF, pick-up

2953

T. Kobayashi, K. Akai, K. Ebihara, A. Kabe, K. Nakanishi, M. Nishiwaki, J.-I. Odagiri
KEK, Ibaraki, Japan
H. Deguchi, K. Harumatsu, K. Hayashi, T. Iwaki, J. Mizuno, J. Nishio, M. Ryoshi
Mitsubishi Electric TOKKI Systems, Amagasaki, Hyogo, Japan

For the SuperKEKB project, a new LLRF control system was developed to realize high accuracy and flexibility. It is an FPGA-based digital RF feedback control system using 16-bit ADC's, which works on the μTCA platform. The FPGA boards control accelerating cavity fields and cavity tuning, and the EPICS-IOC is embedded in each of them. The CSS-BOY was adopted for a user interface of our system. High power test of the new LLRF control system was performed with the ARES Cavity of KEKB. The obtained feedback control stability with a klystron drive was sufficient as well as the low-level evaluation result. And auto tuner control also worded successfully. The start-up sequencer program for the cavity operation and auto-aging program also worked very well. The temperature characteristics of the system depend largely on band-pass filters (BPF). We tried to tune the BPF to reduce the temperature coefficient. Consequently the temperature dependence was improved to satisfy the required stability.

WEPME015

Evaluation of the Superconducting LLRF system at cERL in KEK

LLRF, controls, coupling, linac

2956

F. Qiu, D.A. Arakawa, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura, T. Miyajima, K. Tsuchiya
KEK, Ibaraki, Japan

A low level RF (LLRF) design is being currently developed within the compact Energy Recover Linac (cERL) at KEK. One challenging task is to achieve the high amplitude and high phase stability required by the accelerating fields of up to 0.1% and 0.1°, respectively. To improve the performance of the LLRF system, a gain scanning experiment for determining the optimal controller gain was carried out on the cERL. Furthermore, as a substitute for the traditional PI controller, a more robust H∞-based multiple input multiple output (MIMO) controller was realized. This controller requires more detailed system information (transfer function or state equation), which can be acquired by using modern system identification methods. In this paper, we describe the current status of these experiments on the cERL.

WEPME021

Development of CO2 Laser Optical Enhancement Cavity for a Laser-Compton X-ray Source

laser, scattering, polarization, photon

2974

K. Ando, A. Endo, K. Sakaue, T. Takeichi, M. Washio
Waseda University, Tokyo, Japan

Funding: Work supported by NEDO (New Energy and Industrial Technology Development Organization).
We have been developing a laser-Compton X-ray source using optical enhancement cavity. We have studied 1um pulse laser storage in optical cavity and use for the experiments. Usage of 10um laser for optical enhancement cavity will increase the X-ray energy region of one laser-Compton X-ray source, so that we decided to develop the optical cavity for CO2 laser. We have designed external optical cavity for CO2 laser commercially available optics and verified the enhancement of CO2 laser in external optical cavity, and measured fundamental parameters such as finesse, matching efficiency, and enhancement factor. We have already achieved 540 of finesse, 43 of enhancement, and tested non-planer cavity, which storages two circular polarization separately. In this conference, we will report the design and experimental results of CO2 laser storage cavity and also some future prospects.

WEPME022

Overview of the CSNS/RCS LLRF Control System

controls, LLRF, feedback, beam-loading

2977

X. Li, W. Long, H. Sun, C.L. Zhang, F.C. Zhao
IHEP, Beijing, People's Republic of China

The CSNS/RCS RF system consists of 8 ferrite-loaded RF cavities (h=2), each with individual digital LLRF control electronics. The injection and extraction energy of the beam are 80MeV and 1.6GeV respectively with a repetition rate of 25Hz. The RF system is designed to provide the maximum RF voltage of 165kV. The RF frequency range is from 1.02MHz at injection to 2.44MHz at extraction. The CSNS/RCS LLRF control system is based on FPGA, and composed of 7 control loops to achieve required acceleration voltage amplitude and phase regulation. A number of prototype and the first formal system have been completed and tested. In this paper we present an overview of the LLRF control system, and some operational results.

WEPME024

Gaussian Spectrum Fiber Laser Pulses Generated in an All-normal-dispersion Cavity

laser, controls, background, status

2983

Y. You, W.-H. Huang, C.-X. Tang, L.X. Yan
TUB, Beijing, People's Republic of China
H. Shimizu, J. Urakawa
KEK, Ibaraki, Japan

In this paper, we reported generating a broad bandwidth Gaussian shape spectrum fiber laser pulse directly in an all-normal dispersive cavity. Pulse-shaping is based on spectral filtering. The spectrum has a ~20 nm 20-dB spectrum bandwidth and it is different from the typical spectrum, of steep edge and two spikes. The Gaussian spectrum is preferred since it can be dechirped to transform-limited pulsed duration. The pulse duration corresponds to this kind of spectrum is ~315fs, and pulse energy is up to~9nJ, with a repetition rate of 18.9MHz.

WEPME036

The Development of LLRF System at PAL

LLRF, controls, radio-frequency, monitoring

3004

K.-H. Park, H.S. Han, Y.-G. Jung, D.E. Kim, H.-G. Lee, H.S. Suh
PAL, Pohang, Kyungbuk, Republic of Korea
J.-S. Chai, Y.S. Lee
SKKU, Suwon, Republic of Korea
B.-K. Kang
POSTECH, Pohang, Kyungbuk, Republic of Korea

The PAL has been developing the low level radio frequency (LLRF) system. The required field stabilities of the LLRF system are within ±0.75% in amplitude and 0.35° in phase in a cavity. All the hardware including RF front–end, FPGA with peripherals such as ADC, DAC, Oscillator and digital interface were assembled. The sub-modules for the RF signal processing were written by VHDL and integrated to test at the local facility. The macroblaze software processor was implemented to make the system simple in interfacing to peripherals and to secure flexibility later. This paper described the microblaze processor which was ported into the VERTEX6 FPGA. And also this paper showed the test results of the each module and integrated into the full system.

WEPME040

Investigation to Reduce Power Overhead Required in Superconducting RF Cavity Field Control

klystron, controls, feedback, cathode

3013

R. Zeng, S. Molloy, A. Sunesson
ESS, Lund, Sweden
A.J. Johansson
Lund University, Lund, Sweden

A power overhead of more than 25% is usually required in RF field control of klystron drived superconducting cavity, since it is much easier to implement feild control in a linear region of klystron where it is far below saturation. It however results in a reduced efficiency and more power consumption. Within ESS project it places very high demands on energy efficiency, which leads to stringent requirements on power overhead required in RF field control. Investigation on power overhead reduction in RF field control has been carried out at ESS and related simulation has been done. In this paper we will look at how close we can implement field control to the klystron saturation and discuss if it is possible to make RF field control the RF field with 10% overhead.

WEPME052

LLRF Characterisation of the Daresbury International Cryomodule

LLRF, cryomodule, resonance, SRF

3046

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

The 2-cavity Superconducting RF (SRF) Linac cryomodule of the Accelerators and Lasers in Combined Experiments (ALICE) located at Daresbury Laboratory will be replaced by a new International ERL Cryomodule in early 2013. The improved 7-cell, 1.3 GHz SRF cavities will be characterised and compared with the original 9-cell cavities. Tests will be performed by driving the cavities by a VCO-PLL loop so that Q measurements, microphonics sensitivity and Lorentz force detuning can be analysed. A digital LLRF system using the LLRF4 board developed by Larry Doolittle has been developed at Daresbury Laboratory and will be installed on the upgraded cryomodule. This system is capable of controlled cavity filling to reduce waveguide reflection voltage, feedback/feed forward control and adaptive beam loading compensation. The new cryomodule will be evaluated with both the analog LLRF system and the digital LLRF system to allow for performance comparison. Cavity operation with high QL will also be tested to discover the feedback control limit as a function of inherent microphonics. This paper sets out to discuss the qualification process, testing and results of the upgraded cryomodule installation.

WEPME053

Latest Performance Results from the FONT 5 Intra Train Beam Position Feedback System at ATF

feedback, kicker, extraction, linear-collider

3049

M.R. Davis, D.R. Bett, N. Blaskovic Kraljevic, P. Burrows, G.B. Christian, Y.I. Kim, C. Perry
JAI, Oxford, United Kingdom
R. Apsimon, B. Constance, A. Gerbershagen
CERN, Geneva, Switzerland

A prototype ultra-fast beam-based feedback system for deployment in single-pass beamlines, such as a future lepton collider (ILC or CLIC) or a free-electron laser, has been fabricated and is being tested in the extraction and final focus lines of the Accelerator Test Facility (ATF) at KEK. FONT5 is an intra-train feedback system for stabilising the beam orbit via different methods: a position and angle feedback correction in the extraction line or a vertical feedforward correction applied at the interaction point (IP) . Two systems comprise three stripline beam position monitors (BPMs) and two stripline kickers in the extraction line, two cavity BPMs and a stripline kicker at the IP, a custom FPGA-based digital processing board, custom kicker-drive amplifiers and low-latency analogue front-end BPM processors. Latest results from the experiment are presented. These include beam position correction in the extraction line, as well as preliminary results of beam correction at the IP.

WEPME058

Integrated System Modeling Analysis of a Multi-cell Deflecting-mode Cavity in Cryogenic Operation

simulation, cryomodule, vacuum, coupling

3064

Y.-M. Shin, M.D. Church, J. Ruan
Fermilab, Batavia, USA

Over the past decade, multi-cell deflecting (TM110) mode cavities have been employed for experiments on six-dimensional phase-space beam manipulation *,**,***,****,****** at the A0 Photo-Injector Lab (16 MeV) in Fermilab and their extended applications with vacuum cryomodules are currently scheduled at the Advanced Superconducting Test Accelerator (ASTA) user facility (> 50 MeV). Despite the successful test results, the cavity, however, demonstrated limited RF performance during liquid nitrogen (LN2) ambient operation that was inferior to theoretic prediction. We thus fully inspected the cavity design with theoretical calculation (based on Panofsky-Wenzel theorem) combined with RF simulations. Also, we are extensively developing an integrated computational tool with comprehensive system analysis capacity to solve complex thermodynamics and mechanical stresses of a high-Q deflecting-mode cryomodule. We will benchmark simulation analysis result with experimental data from high power RF tests in Fermilab. Successfully developed modeling tool will be potentially used for prompt assessment on RF performance of vacuum-cryomodules.
* D. A. Edwards, LINAC 2002
** Y.-E Sun, PRTAB 2004
*** P. Piot, PRSTAB2006
**** J. Ruand et al., PRL 2011
***** Y.-E. Sun, et al., PRL 2010

WEPME062

Short-Pulse Ti:Sapphire Laser System for Photocathode Research at SLAC

laser, gun, cathode, diagnostics

3076

W.J. Corbett, A. Brachmann, R.N. Coffee, A.R. Fry, S. Gilevich, N. Hartmann, W. Helml, P. Hering, E.N. Jongewaard, D. Kelley, J.R. Lewandowski, W. Polzin, J. Sheppard, P. Stefan, T. Vecchione, S.P. Weathersby, W.E. White, M. Woods, F. Zhou
SLAC, Menlo Park, California, USA

A photo-cathode research laboratory has been constructed at SLAC to test and characterize the spare LCLS electron gun. At the heart of the laboratory is a dual-purpose Ti:Sapphire oscillator/regen laser that can deliver either a 2.5ps, 760nm beam to the photocathode gun or a 35fs, 800nm beam to prototype diagnostics for the LCLS. The objective of the photocathode research is to definitively identify ‘recipes’ for high-reliability cathode processing resulting in high quantum efficiency and low beam emittance. The LCLS diagnostics program is presently aimed at developing spectral-encoding systems for shot-by-shot pulse arrival time measurements at the 10fs level. In this paper we review the Ti:Sapphire laser system and report on status of the photocathode and diagnostics programs.

THOBB101

Transverse-to-longitudinal Emittance Exchange at the Fermilab Advanced Superconducting Test Accelerator

emittance, quadrupole, simulation, controls

3103

C.R. Prokop, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
B.E. Carlsten
LANL, Los Alamos, New Mexico, USA
M.D. Church, P. Piot
Fermilab, Batavia, USA

Funding: LANL LDRD program, project 20110067DR U.S. DoE under Contract No. DE-FG02-08ER41532 with Northern Illinois University and under Contract No. DE-AC02-07CH11359 the Fermi Research Alliance, LLC.
Earlier experiments at Fermilab’s A0 Photoinjector Laboratory demonstrated successful transverse-to-longitudinal emittance exchange (EEX) using a transverse-deflecting cavity (TDC) located between two identical doglegs. Such a design has the disadvantage of transversely displacing the beam. An interesting alternative is an EEX beamline designed out of a variable R56 bunch compressor chicane. In this paper, we present design and simulation testing for a chicane-based EEX for eventual implementation at Fermilab’s Advanced Superconducting Test Accelerator. We explore several advanced EEX concepts, including bunch current profile shaping, bunch compression, and dispersion-boosting to relax the requirements on TDC power and cooling.

Slides THOBB101 [2.582 MB]

THYB201

Where Next with SRF?

SRF, linac, cryomodule, proton

3124

G. Ciovati
JLAB, Newport News, Virginia, USA

Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
RF superconductivity (SRF) has become, over the last ~20 years, the technology of choice to produce RF cavities for particle accelerators. This occurred because of improvements in material and processing techniques as well as the understanding and remediation of practical limitations in SRF cavities. This development effort span ~40 years and Nb has been the material of choice for SRF cavity production. As the performances of SRF Nb cavities are approaching what are considered to be theoretical limits of the material, it is legitimate to ask what will be the future of SRF. In this article we will attempt to answer such question on the basis of near-future demands for SRF-based accelerators and the basic SRF properties of the available materials. Clearly, Nb will continue to play a major role in SRF cavities in the coming years but the use of superconductors with higher critical temperature than Nb is also likely to occur.

Slides THYB201 [1.549 MB]

THOBB201

Pathway to a Post Processing Increase in Q0 of SRF Cavities

shielding, niobium, SRF, cryogenics

3129

O. Kugeler, J. Knobloch, J.M. Vogt
HZB, Berlin, Germany
S. Aull
CERN, Geneva, Switzerland

A significant improvement of Q0 to values larger than 3.2x10¹⁰ at 1.8K has been repeatedly achieved in an SRF cavity by thermal cycling, i.e. heating the cavity briefly above transition temperature and subsequent cooling. Conceivable explanations for this effect reach from effectivity deviations of the magnetic shielding to thermal currents to hydrogen diffusion. Experimental We have experimentally verified some of these explanations, leaving a direct impact of cooling dynamics on frozen flux as the most plausible one. The pathway to this finding is being presented and the application to SRF systems is elicited.

Slides THOBB201 [1.184 MB]

THOBB203

Study on Fabrication of Superconducting RF 9-cell Cavity for ILC at KEK

HOM, electron, gun, status

3132

T. Saeki, Y. Ajima, K. Enami, H. Hayano, H. Inoue, E. Kako, S. Kato, S. Koike, T. Kubo, S. Noguchi, M. Satoh, M. Sawabe, T. Shishido, A. Terashima, N. Toge, K. Ueno, K. Umemori, K. Watanabe, Y. Watanabe, S. Yamaguchi, A. Yamamoto, Y. Yamamoto, M. Yamanaka, K. Yokoya
KEK, Ibaraki, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
N. Kawabata, H. Nakamura, K. Nohara, M. Shinohara
SPS, Funabashi-shi, Japan
F. Yasuda
The University of Tokyo, Institute of Physics, Tokyo, Japan

We constructed a new facility for the fabrication of superconducting RF cavity at KEK from 2009 to 2011. In the facility, we have installed a deep-drawing machine, a half-cell trimming machine, an electron-beam welding machine, and a chemical etching room in one place. We started the study on the fabrication of 9-cell cavity for International Linear Collier (ILC) from 2009 using this facility. The study is focusing on the cost reduction with keeping high performance of cavity, and the goal is the establishment of mass-production procedure for ILC. This article reports the current status of the studies in CFF.

Slides THOBB203 [3.983 MB]

THPEA004

Precise Verification of Phase and Amplitude Calibration by means of a Debunching Experiment in SIS18

target, controls, bunching, injection

3155

U. Hartel, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany
J. Grieser, D.E.M. Lens
TU Darmstadt, RTR, Darmstadt, Germany
H. Klingbeil, U. Laier, K.-P. Ningel, S. Schäfer, B. Zipfel
GSI, Darmstadt, Germany

Funding: Work supported by the GSI Helmholtzzentrum für Schwerionenforschung GmbH
Several new rf cavity systems have to be realized for the FAIR synchrotrons and for the upgrade of the existing GSI synchrotron SIS18*. For this purpose, a completely new low-level rf system architecture** has been developed, which is now used in SIS18 operation. Closed-loop control systems stabilize the amplitude and the phase of the rf gap voltages. Due to component imperfections the transmission and the detection of the actual values lead to systematic errors without countermeasures. These errors prohibit the operation of the rf systems over the whole amplitude and frequency range within the required accuracy. To compensate the inevitable errors, the target values provided by the central control system are modified by so-called calibration electronics*** modules. The calibration curves can be measured without the beam, but the desired beam behaviour has to be verified by experiments. For this purpose, a debunching scenario was selected as a SIS18 beam experiment that proved to be very sensitive to inaccuracies. In this contribution the results of this experiment are presented, showing for the first time at GSI by beam observation that the accuracy requirements are met based on predefined calibration curves.
* “FAIR - Baseline Technical Report,” Volume 2, Accelerator and Scientific Infrastructure, (2006).
** Klingbeil et al.: Phys. Rev. ST Accel. Beams 14, 102802, 2011.
*** S. Schaefer et al., “Use of FPGA-based Configurable Electronics to Calibrate Cavities,” THPEA003, these proceedings.

THPEA053

Data Acquisition and Monitoring for TPS SRF Module Horizontal Test

SRF, EPICS, monitoring, controls

3264

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

Three KEKB-type single-cell SRF modules were shipped to NSRRC before the end of 2012. The horizontal test of the first KEKB-type SRF module has been already finished in January of 2013. While the horizontal tests for the next two SRF module will be completed in May and August of this year. This article introduces the data acquisition and monitoring systems during the SRF horizontal test in NSRRC.

THPFI003

Vacuum Study of the Cavity String for the IFMIF - LIPAc Cryomodule

vacuum, cryomodule, pick-up, linac

3291

N. Bazin, G. Devanz, F. Orsini
CEA/DSM/IRFU, France

In the framework of the International Fusion Materials Irradiation Facility (IFMIF), a superconducting option has been chosen for the 5 MeV RF Linac of the first phase of the project (EVEDA), based on a cryomodule composed of 8 HWRs, 8 RF couplers and 8 Solenoid packages. This paper will focus on the beam vacuum of the cryomodule. The cryomodule beam line is made of the pattern solenoid package / cavity-coupler, and a valve on each side of the cryomodule. During the installation of the cryomodule on the accelerator system, the cavity string has to be pumped down with the beam valves closed. Thereby a manifold is connected to the cavities during the assembly of the beam line components in the clean room. In previous conferences, the cryomodule was presented with a vacuum manifold connected to each cavity. A study realized on this complex vacuum configuration with Molflow, a test-particle Monte-Carlo simulator for ultra-high vacuum, permitted to reduce the number of cavities connected to the manifold and by consequence to reduce the risk of pollution during the clean room assembly.

THPFI008

Experience and Benefits from PLM-based Parts Management at European XFEL

controls, linac, factory, undulator

3306

L. Hagge, J.A. Dammann, S. Eucker, A. Frank, J. Kreutzkamp, D. Käfer, D. Szepielak, N. Welle
DESY, Hamburg, Germany

DESY has developed a parts management solution, which is used in the series fabrication of accelerator components for the European XFEL. The parts management solution stores assembly instructions and drawings for each component, and it tracks the assembly progress of each individual component. It offers procedures for quality inspections, for handling non-conformities and for managing changes, and it tracks the current whereabouts and the entire history of each part. The solution is based on DESY's Product Lifecycle Management (PLM) System and integrates several laboratories and suppliers. The poster shows how parts management is used at the European XFEL in the production of the super-conducting rf cavities, in the assembly of the cryomodules and in the assembly of the undulators, and discusses experience and benefits.

THPFI013

Development of Cylindrical-type 1.2 MW High Power Water-load for Super KEKB

klystron, positron, collider, factory

3318

K. Watanabe, K. Ebihara, A. Kabe, K. Marutsuka, M. Nishiwaki
KEK, Ibaraki, Japan
Y. Kawane, A. Miura
Nihon Koshuha Co. Ltd, Yokohama, Japan

We have developed and manufactured CW 1.2 MW high power water-load for the use of the Super KEKB, an electron – positron double-ring collider at KEK. The tank and rf window of the water-load is the circular and cylindrical-type. The material to absorb the rf power is a tap water. This load is equipped on the 3rd port of the circulators to safe the 1.2 MW CW klystrons to drive the ARES cavities in main ring. The operational frequency is 508.9 MHz. A proto-type model of this water-load was fabricated at Sep 2012, and tested using by high power klystron (1 MW) at Oct 2012 at KEK D2-ET station. The result of high power test will be reported in this paper.

THPFI025

Design and Experimental Results of an Electro-static Pre-chopper for CSNS LEBT

rfq, power-supply, radiation, simulation

3351

H.C. Liu, S. Fu, K.Y. Gong, H.F. Ouyang, J. Peng
IHEP, Beijing, People's Republic of China

The China Spallation Neutron Source (CSNS) front end incorporates a pre-chopper in the Low Energy Beam Transport line (LEBT) that will remove a 530ns section of beam at approximately 1MHz rate, which is the RF frequency of the ring at injection. It’s one of the most critical devices for properly controlling the injecting beam loss. Physical designing of the pre-chopper is carried out, and the RFQ itself was used as the beam dump of the chopper system. In order to examine the reliability of the pre-chopper design, the beam study of a similar chopper system was successfully performed. Results of physical design and experiments will be presented.

THPFI035

Design of A 4-cavities Collinear Load Coated with FeSiAl Alloy for 14 MeV LINAC

simulation, linac, target, instrumentation

3370

F. Zhang, L.G. Shen
USTC/PMPI, Hefei, Anhui, People's Republic of China
Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China

Collinear load is a substitute for waveguide load to miniaturize linear accelerator and make the beam quality better. Coating with a kind of high efficient microwave-absorbing material FeSiAl alloy, a collinear load section composed of 4 cavities (at 2 /3 mode) with different coating dimensions is designed to absorb 4kW remnant power. Cavity dimensions are adjusted to compensate the frequency shift from 2856 MHz respectively. Simulation shows the loss material FeSiAl only need to be coated on the inner surface of the ring. This makes the design and construction of the cooling system for the load segment easier. Coming with a specific water cooling system can makes the working frequency of the accelerator and the collinear load more close to the supposed. Eventually, based on optimized uniform power absorption principle concluded from the simulation of temperature field, a four-cavity collinear load is designed with one-way attenuation of 76.1 dB, while the largest shift from operation frequency is 35 kHz.

THPFI042

Design Considerations for Phase Reference Distribution System at ESS

linac, controls, LLRF, radiation

3379

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

PRDS (Phase Reference Distribution System) will be serving as the phase alignment line for all cavities with high phase stability. With the current design of individually RF source powering for most cavities at ESS, phase reference distribution system should provide the reference signals for totally 34 LLRF systems at 100 meters long low-frequency section (for all 352.21MHz cavities, including RFQ, DTL, bunching cavities and spokes), and for totally 180 LLRF systems at 342 meters long high-frequency section (for all 704.42MHz cavities, including medium beta and high beta elliptical cavities). Coaxial cable based solution and optical fibre based solution are discussed in this note for PRDS (Phase reference distribution system) at ESS. Some possible schemes in each of these two distribution solutions are introduced and comparisons among these schemes are made. Some effort is made as well to find out a reasonable design for PRDS at ESS.

THPFI062

Design of Air-cooled Beam Dump for Extraction Line of PS Booster

shielding, simulation, booster, proton

3436

A. Perillo-Marcone, T. Antonakakis, M. Battistin, M.A. Czapski, G.W. Mason, E.M. Nowak, A. Sarrió Martínez, S. Sgobba, V. Venturi, V. Vlachoudis
CERN, Geneva, Switzerland

A new beam dump has been designed, which withstands the future proton beam extracted from the PS Booster at CERN, consisting of up to 10¹⁴ protons per pulse at 2 GeV after its upgrade in 2018/2019. In order to be able to efficiently release the deposited heat, the new dump will be made out of a single cylindrical block of a copper alloy and be cooled by forced ventilation. In order to determine the energy density distribution deposited by the beam in the dump, Monte Carlo simulations were performed using FLUKA, and thermo-mechanical analyses carried out by importing the energy density into Ansys. In addition, CFD simulations of the airflow were carried out in order to accurately estimate the heat transfer convection coefficient on the surface of the dump. In this paper we describe the design process and highlight the constraints of integrating a new dump for increased beam power into the existing facility.

THPME002

Compact High-Tc 2G Superconducting Solenoid for Superconducting RF Electron Gun

solenoid, gun, electron, SRF

3514

G. Nielsen, A. Baurichter, N. Hauge, E.K. Krauthammer
Danfysik A/S, Taastrup, Denmark

A solenoid with second generation (2G) high-temperature superconducting (HTS) coils for use in the superconducting RF electron gun of the WiFEL free electron laser at the University of Wisconsin, Madison, has successfully been designed, manufactured, tested and magnetically characterized at Danfysik. The solenoid is designed to operate in the temperature range between 5 K and 70 K. A stack of 16 serially connected pancake coils wound from SuperPower 2G HTS-tape is mounted inside a cylindrical iron yoke with end caps. The solenoid was designed with an excitation current margin of at least 130 % of the nominal operation current in the whole temperature range. At operation, 17.2 kA-turns yield a center field of 0.20 T and a field integral of 3.1 T² mm, with very small integrated field errors. With a yoke outer diameter of 176 mm and a total length of 136 mm, the solenoid is very compact, and can therefore be placed very close to the RF cavity, improving its emittance compensating efficiency. Careful magnetic design minimizes the leak field at the SC cavity surface. Heat dissipation is negligible hence conduction cooling through copper braids attached to the iron yoke is sufficient.

THPME010

Magnetic Shielding for the 1.3 GHz Cryomodule at IHEP

shielding, simulation, SRF, cryomodule

3528

S. Jin, Y. Chen, J. Gao, R. Ge, Y. Liu, Z.C. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng
IHEP, Beijing, People's Republic of China
F. Yang
China Iron and Steel Research Institute Group, Beijing, People's Republic of China

An ILC-type Superconducting RF (SRF) accelerating unit is being studied at IHEP. In order to achieve the design performance including both accelerating gradient and quality factor, the SRF cavity must be cooled with ambient magnetic field well shielded to the level of several mG[1,2]. In this paper, permeability of several kinds of materials for magnetic shielding made in China is systematically studied in cooperation with China Iron & Steel Research Institute Group (CISRI) and reported for the first time. By using proper material, numerical calculation for the magnetic shielding design was done via the program of Opera-3D, and then magnetic shield was fabricated by CISRI. This paper will show those studies above and the final magnetic shielding effect at room temperature. Comparisons between simulation result and real effect will also be discussed in the paper, as well as the preliminary analysis for the magnetic field leaking of this design.

THPME019

Design of the Cold Mass Support Assembly of Test Cryomodule for IMP ADS-Injector II

solenoid, controls, cryomodule, vacuum

3543

Y. Liu, S. Sun, J. Wang, L. Wang, S.Y. Wang
SINAP, Shanghai, People's Republic of China
X.L. Guo
JiangShu University, Jiangsu Province, People's Republic of China

In order to test the performance of the HWR cavities and verify the related technique for cooling of the cavities and the solenoids together, a test cryomodule (TCM1) containing one superconducting HWR cavity followed by one cold BPM and two superconducting solenoids was developed for the Injector II of the Accelerator Driven Sub-critical System (ADS). The TCM1 consists of the cryostat and the cold mass assembly. The cryostat is composed of vacuum chamber, thermal shields, cooling circuit, cold mass support assembly, and instrumentation. A set of cold mass support assembly was developed for supporting the cold mass working at 4.4 K. The support assembly mainly consists of Ti support frame, stainless steel rods, adjustable mechanisms and LHe cooling passage. It can not only support the weight of the cold mass but also stand the thermal stress during the cool down. In order not to affect the performance of the cavity, it will not impose any force on the HWR cavity. It can be adjustable for alignment of the cold mass both at room temperature and 4.4 K. This paper provides the detailed design of the TCM1 cold mass support assembly.

THPME020

Design of a Test Cryomodule for IMP ADS-Injector II

solenoid, cryomodule, vacuum, radiation

3546

L. Wang, Y. Liu, S. Sun, J. Wang, S.Y. Wang, S.H. Wang
SINAP, Shanghai, People's Republic of China
X.L. Guo
JiangShu University, Jiangsu Province, People's Republic of China

Two cryomodules are to be applied for the Injector II of the Accelerator Driven Sub-critical System. Each of them will contain 8 superconducting HWR cavities and 9 superconducting solenoids. In order to test the performance of the HWR cavities and validate related technique for cooling of cavities and solenoids together, a test cryomodule (TCM1) including one HWR cavity and two solenoids was developed. The design of the TCM1 cryostat was carried out by the Shanghai Institute of Applied Physics, CAS. Both the cavity and the solenoids will work at 4.4 K by bath cooling. The fast cooling down for the cavity from 100 K to 120 K is required to avoid degrading of the cavity performance. Before energization, the solenoids can be warmed up to above 10 K and re-cooled down for degaussing. The TCM1 can not only be cooled by using the dewar-filling system, but also operated by the refrigerator system. The main components of the cryostat include vacuum chamber, thermal shields, magnet current leads, cooling circuit, and cold mass support assembly. This paper presents the detailed design of the TCM1 cryostat.

THPME025

Design of Cryomodules for RAON

cryomodule, cryogenics, linac, vacuum

3558

Y. Kim, C. Choi, D. Jeon, H.J. Kim, M. Lee
IBS, Daejeon, Republic of Korea

The RAON linac utilizes four types of superconducting cavities such as QWR, HWR, SSR1, and SSR2 which are operating at 2 K in order to accelerate the various ion beams. The main role of the cryomodules is to maintain the cryogenic temperature for the superconducting cavity operation. Five types of cryomodules will be necessary since one QWR cavity, three and six HWR cavities, four SSR1 cavities, and eight SSR2 cavities will be installed in the dedicated cryomdoules. Total number of the cryomodule is 147, 48 for QWR, 60 for HWR, 22 for SSR1, 17 for SSR2. The cryomodules of RAON does not include focusing magnets but includes the cavities operating at 2 K. This paper describes the current status of the RAON cryomodule design. The issues included in the paper are the thermal load estimation, design of the components such as thermal shield and intercept of the cryomodules, and cryogenic flow circulation system according to the cryomodule operation.

THPME035

The Electronic System Design and Realization for First Set 500 MHz KEKB SRF Module High Power Test

SRF, controls, cryogenics, HOM

3588

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

This article reports the home-made electronics circuits for reading the various electronics signals which can be used for site acceptance of superconducting resonant cavity. The adjustment of parameters during 1st SRF high power acceptance can also be used for the update of the 2nd electronics. The modular electronics system will provide the advantages of fast repair, preparing spare parts easily, short install time and flexible adjustment. The hardware whole electronics system is mainly designed by CPLD, PLC and Display meters. The Military Standard connectors are used for signals connection. There are always junction boxes for signal transmission test and convenient signal jumping for ensuring the correct signal source. In safety action, there are Fast Interlock Sum (0-10us) and slow ready chain (50ms-150ms). The complete system realizes the real time monitor and protection of superconducting resonant cavity.

THPWA001

Design of X-Band Medical Linear Accelerator with Multiple RF Feeds and RF Phase Focusing

focusing, linac, impedance, bunching

3627

Y. N. Nour El-Din, T.M. Abuelfadl
Cairo University, Giza, Egypt

Funding: Work supported by the Egyptian Science and Technology Development Fund (STDF) No. 953.
A design of 6 MeV X-band 9.3 GHz medical linear accelerator is presented. It is composed of four separate clusters of accelerating cavities, where a coherent RF excitation is provided separately to each cluster. The use of multiple accelerating sections with multiple RF feeds permits the use of inexpensive RF sources. The first cluster is Alternate Phase Focusing (APF) RF cavities, providing radial and longitudinal beam focusing without the use of heavy and bulky magnets or solenoids. The three other clusters used for acceleration are composed of multiple standing wave sections operating in the Pi-mode. Each section has been designed and optimized for high shunt impedance by means of 2D SUPERFISH code and 3D CST code. A two dimensional code, named PTCC, was developed to facilitate design and analysis of the different parts of the accelerating structure.

THPWA012

The Development of a New Type of Electron Microscope using Superconducting RF Acceleration

acceleration, electron, gun, cathode

3654

N. Higashi
The University of Tokyo, Graduate School of Science, Tokyo, Japan
A. Enomoto, Y. Funahashi, T. Furuya, Y. Kamiya, S. Michizono, M. Nishiwaki, H. Sakai, M. Sawabe, K. Ueno, M. Yamamoto
KEK, Ibaraki, Japan
M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan
S. Yamashita
ICEPP, Tokyo, Japan

We are developing a new type of electron microscope (EM), which adopts RF acceleration in order to exceed the energy limit of DC acceleration used in conventional EMs. It enables us to make a high-voltage EM more compact and to examine thicker specimens, and possibly to get better spatial resolution. Using a superconducting RF cavity, we can operate the EM in CW mode to obtain a beam flux comparable to that in DC mode. Low energy dispersion ΔE/E , e.g. 10^-6 or better, is required for good spatial resolution in EMs, while it is usually between 10^-3 to 10^-4 in accelerators. We have thus designed a special type of cavity that can be excited with the fundamental and second-harmonic frequencies simultaneously; TM010 and TM020. With the two-mode cavity, the energy dispersion of the order of 10^-5 would be obtained by modifying the peak of accelerating field to be flattened. As the proof-of-principle of our concept, we are developing the prototype using a 300 keV transmission electron microscope (TEM), to which a new photocathode gun and the two-mode cavity are attached. We have already manufactured the cavity and it is under test, and the gun is under construction.

THPWO001

Assembling, Testing and Installing the SPIRAL2 Superconducting Linac

cryomodule, linac, vacuum, alignment

3752

P.-E. Bernaudin, R. Ferdinand
GANIL, Caen, France
P. Bosland
CEA/DSM/IRFU, France
Y. Gomez Martinez
LPSC, Grenoble, France
G. Olry
IPN, Orsay, France

Assembly and tests of the SPIRAL2 superconducting linac's components are now proceeding smoothly. Cryomodules are being processed in CEA Saclay and IPN Orsay, inter-cryomodules "warm" sections in GANIL. While installation of the accelerators components is going on in the new SPIRAL2 building in Caen, installation of the cryomodules will begin during the last quarter of 2013. The latest results of the cryomodules tests as well as the installation strategy are depicted in this paper.

THPWO007

Advanced Superconducting CW Heavy Ion Linac R&D

solenoid, linac, ion, heavy-ion

3770

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

An advanced upgrade program has to be realized in the next years, such that enhanced primary beam intensities are available. For this a new sc 28 GHz full performance ECR ion source has to be established. Via a new low energy beam line an already installed new RFQ and an IH-DTL will provide for cw-heavy ion beams with high average beam intensity. It is foreseen to build a new cw-heavy ion-linac behind this high charge state injector. In preparation an advanced R&D program is defined: The first linac section comprising a sc CH-cavity embedded by two sc solenoids (financed by HIM and partly by HGF-ARD-initiative) as a demonstrator will be tested in 2014). After successfull testing an advanced cryomodule comprising up to 4 rf cavities is foreseen. First layout scenarios of this advanced test bench will be presented.

THPWO008

Status of the 70 MeV FAIR Proton Injector

proton, linac, DTL, rfq

3773

G. Clemente, W.A. Barth, R. Bereznov, P. Forck, L. Groening, R. Hollinger, M. Kaiser, A. Krämer, F. Maimone, C. Mühle, J. Pfister, G. Schreiber, J. Trüller, W. Vinzenz, C. Will
GSI, Darmstadt, Germany
R. M. Brodhage, B. Koubek, H. Podlech, U. Ratzinger, A. Schempp, R. Tiede
IAP, Frankfurt am Main, Germany
N. Chauvin, O. Delferrière
CEA/IRFU, Gif-sur-Yvette, France
B. Launé, J. Lesrel
IPN, Orsay, France
C.S. Simon, O. Tuske
CEA/DSM/IRFU, France

Funding: BMBF
The FAIR project requires a dedicated proton injector for the creation of high intensity secondary antiproton beams. This machine will be the first high intensity linear accelerator based on CH-DTL. The status of the project, with particular emphasis on the construction of the first RF prototype is presented.

THPWO012

High Gradient Room Temperature Cavity Development for 10 – 100 AMeV Beams

linac, focusing, ion, DTL

3785

A. Almomani, U. Ratzinger
IAP, Frankfurt am Main, Germany

Funding: BMBF, 05P12RFRB9
These linac activities are aimed to increase the accelerating field gradient. In IAP – Frankfurt, a CH – design was proposed to post-accelerate a proton bunch, generated by an intense laser, from 10 – 15.2 MeV. The accelerating field gradient is expected to reach > 10 MV/m. Within a funded project, this cavity will be further developed towards a high gradient cavity. The availability of the GSI 3 MW klystron test stand will be very important for these investigations. The results will influence the rebuilt of the Unilac - Alvarez section, where the existing linac tunnel with 1 m thick concrete walls should house a powerful pulsed heavy ion linac, optimized for achieving finally the beam intensities specified for the GSI-FAIR project. The status of the cavity design will be presented.

THPWO014

Design Study of a High Frequency Proton Ladder RFQ

rfq, proton, dipole, antiproton

3788

R. M. Brodhage, A. Almomani, U. Ratzinger
IAP, Frankfurt am Main, Germany

For the research program with cooled antiprotons at FAIR a dedicated 70 MeV, 70 mA proton injector is required. In the low energy section, between the Ion Source and the main linac an RFQ has to be designed. Accelerating protons from 95 keV to 3.0 MeV the RFQ will oscillate at 325 MHz. This particular high frequency for an RFQ creates difficulties which are challenging in developing this cavity. In order to define a satisfactory geometrical configuration for this resonator, both from the RF and the mechanical point of view, different designs have been examined and compared. Very promising results have been reached with an ladder type RFQ, especially concerning the dipole component of the accelerating fields, which is almost not noticeable. This paper will show 3D simulations of the general layout and a whole cavity demonstrating the power of a ladder type RFQ. It will outline a possible layout for the RFQ within the new FAIR proton injector.

THPWO015

First Coupled CH Power Cavity for the FAIR Proton Injector

linac, coupling, proton, alignment

3791

R. M. Brodhage, U. Ratzinger
IAP, Frankfurt am Main, Germany
G. Clemente, W. Vinzenz
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. In Summer 2012, the assembly and tuning of the first power prototype was finished. Until then, the cavity was tested with a preliminary aluminum drift tube structure, which was used for precise frequency and field tuning. Before Spring 2013 the final drift tube structure will be welded inside the main tanks and the preparation for copper plating will take place. This paper will report on the main tuning and commissioning steps towards that novel type of DTL and it will show the latest results measured on a fully operational CH proton cavity.

THPWO016

Superconducting CH Cavities for Heavy Ion Acceleration

linac, solenoid, cryomodule, status

3794

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

Funding: Work supported by HIM, GSI and BMBF Contr. No. 06FY7102
To demonstrate the operation ability of superconducting (sc) Crossbar-H-mode (CH) cavity technology a 217 MHz structure of this type is under development at the Institute for Applied Physics (IAP) of Frankfurt University. The cavity has 15 accelerating cells and a design beta of 0.059. It will be equipped with all necessary auxiliaries like a 10 kW power coupler and a tuning system. Currently, the cavity is under construction. Furthermore, this cavity will serve as demonstrator for a sc continuous wave (cw) LINAC at GSI. The proposed cw LINAC is highly requested to fulfil the requirements of nuclear chemistry and especially for a competitive production of new Super Heavy Elements (SHE) in the future. A full performance test by injecting and accelerating a beam from the GSI High Charge Injector (HLI) is planned in 2014. The current status of the sc CH cavity and the demonstrator project is presented.

THPWO017

A Coupled RFQ-IH Cavity for the Neutron Source FRANZ

rfq, DTL, linac, simulation

3797

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

The Frankfurt neutron Source at the Stern-Gerlach-Zentrum (FRANZ) delivers neutrons in the energy range from 1 to 300 keV at high intensities. The neutrons are produced using the the 7Li(p,n)7Be reaction with 2 MeV protons. The linac accelerator cavities consists of a 4-rod-RFQ coupled with an 8 gap interdigital H-type drift tube section with a total cavity length of 2.3 m. It accelerates the 120 keV beam to 2.03 MeV at a frequency of 175 MHz. The combined cavity will be powered by one RF amplifier to reduce investment and operation costs. The inductive power coupler will be located at the RFQ part. The coupling into the IH – section is provided by direct inductive coupling within the cavity. The coupled RFQ-IH combination is investigated with CST-MWS-simulations and by an RF model. The linac combination has to match the resonance frequency, flatness along the RFQ and the voltage ratio between both cavity sections. Beam operation will be cw (a few mA) and pulsed 250 kHz, 50 ns (up to 50 mA and beyond). The thermal cavity losses are about 200 kW and the cooling is the challenging topic.

THPWO018

Power Tests of the 325 MHz 4-ROD RFQ Prototype

rfq, impedance, pick-up, simulation

3800

B. Koubek, H. Podlech, A. Schempp, J.S. Schmidt
IAP, Frankfurt am Main, Germany

For the FAIR project of GSI as part of the proton linac a 325 MHz RFQ with an output energy of 3 MeV is planned. Simulations that have lead to a prototype of a 4-Rod Radio Frequency Quadrupole (RFQ) have been done. The RF parameters have been verified with the prototype. Power tests of this 6 stem copper RFQ should now verify parameters like shunt impedance, electrode voltage and give answers of how much power the structure can sustain.

THPWO020

Simulations on the Boundary Fields of 4-rod RFQ Electrodes

rfq, simulation, quadrupole, shielding

3803

J.S. Schmidt, B. Koubek, A. Schempp
IAP, Frankfurt am Main, Germany

If the RF design of a 4-rod Radio Frequency Quadrupole (RFQ) is not performed carefully with respect to the boundary fields of its electrodes, it can produce errors compared to beam dynamic simulations. An additional field component can be induced on the beam axis, which influences the properties of the particle beam, like energy per nucleon for example, dramatically. Therefore, the influences of different geometric parameters of 4-rod RFQs on these fields have been studied in detail. The results of these simulations will be presented in this paper.

THPWO034

Fabrication of the RFQ III for the J-PARC Linac Current Upgrade

rfq, linac, dipole, quadrupole

3839

T. Morishita, Y. Kondo, H. Oguri
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
K. Hasegawa
JAEA, Ibaraki-ken, Japan
H. Kawamata, F. Naito, T. Sugimura
KEK, Ibaraki, Japan

The J-PARC accelerator comprises an injector linac, a 3-GeV Rapid-Cycling Synchrotron and a 50-GeV Main Ring. The J-PARC linac has been operating for users with the beam energy of 181 MeV. The energy (to 400MeV) and current (to 50mA) upgrade of the linac is scheduled for 1MW operation at RCS. For the current upgrade, the RFQ III, which is designed for 50mA beam acceleration, has been fabricated. The engineering design and the fabrication technologies are basically the same as the RFQ II in J-PARC linac. Some engineering methods are improved for the dimension accuracy, the reliability, and the period of fabrication. In the RFQ II fabrication, there was a leakage trouble at the electron-beam-welding spot by the thermal stress at the brazing only occasionally. Then, we changed to all-brazing design. Also, there was a vane deformation after the final machining. This was corrected by changing the method of fixation at the brazing. As a result, a dimension error was in a tolerable range. Currently, the fabrication is in a final process and the high-power test is scheduled at the second quarter of 2012.

THPWO036

Annular-Ring Coupled Structure Linac for the J-PARC Linac Energy Upgrade

vacuum, linac, ion, proton

3845

H. Ao, H. Asano, Y. Nemoto, N. Ouchi, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
F. Naito, K. Takata
KEK, Ibaraki, Japan

The linac of Japan Proton Accelerator Research Complex (J-PARC) is the injector to the 3-GeV rapid cycle synchrotron. In order to increase the beam power of the synchrotron, the task of the 400-MeV energy upgrade of the linac started from March 2009. Following the 191-MeV Separated-type DTL, the 25 modules of the Annular-ring Coupled Structure (ACS) linac will be added from August 2013. The operating frequency and the accelerating field E0 of the ACS are 972 MHz and 4.2 MV/m, respectively. The cavity fabrication of the ACS has been almost finished, and then the completed cavities are stored in the J-PARC site. Currently, pumps and vacuum components are being installed on the cavities for the test of vacuum condition. For the pulsed beam of J-PARC, the vacuum pressure have to be less than 10^-6 Pa in order not to exceed 0.1 W/m beam loss. In this paper, we present the R&D results to reduce the vacuum pressure using the stored ACS cavity and the current status of the energy upgrade.

THPWO040

Progress of Injector-1 and Main Linac of Chinese ADS Proton Accelerator

rfq, linac, proton, solenoid

3854

Y.L. Chi, J. Cao, J.P. Dai, H. Dong, L. Dong, T.M. Huang, X. Jing, S.P. Li, Z. Li, Z.Q. Li, Z.C. Liu, F. Long, Z. Ma, H.F. Ouyang, W.M. Pan, Q.L. Peng, P. Su, Y.F. Sui, J.Y. Tang, J.L. Wang, Q.B. Wang, Q. Ye, Z.S. Zhou
IHEP, Beijing, People's Republic of China

China ADS study program was Supported by the "Strategic Priority Research Program " of the Chinese Academy of Sciences at 2011, which aims to design and build an ADS demonstration facility with the capability of more than 1000 MW thermal power in about twenty years. The driver Linac is defined to be1.5 GeV in energy, 10mA in current and in CW operation mode. To meet the extremely high reliability and availability of ADS, the Linac is designed with much installed margin and fault tolerance. ADS accelerator is composed of two parallel 10MeV injectors and a main Linac. The superconducting acceleration structures are employed except the RFQs. This paper will present design of the China ADS accelerator and related key technology developments.

THPWO041

The development of a high power input coupler for China ADS injector I RFQ

rfq, coupling, vacuum, injection

3857

T.M. Huang, X. Chen, R. Guo, H.Y. Lin, Q. Ma, F. Meng, H.F. Ouyang, W.M. Pan, X.H. Peng, Z. Zhang, G.Y. Zhao
IHEP, Beijing, People's Republic of China

A 325 MHz RFQ is designed to accelerate a beam current of 15 mA in CW mode with injection energy of 35 keV and output energy of 3.2 MeV for China Accelerator Driven sub-critical System (ADS) injector I. Total RF power of 320 kW has to be delivered into the RFQ cavity. For reliable operation, four input couplers are adopted to share the driven power. A coaxial loop type input coupler is developed. The coupler features a Tristan type RF window, a doorknob to realize the transition from a half-height WR2300 waveguide to a coaxial line and a coaxial line with a coupling antenna loop. Two prototypes of the window and inner conductor assemblies have been fabricated and received high power test. The prototypes were tested up to 100 kW CW RF power in traveling wave mode. This paper will describe the design, fabrication and high power test of the coupler in details.

THPWO043

Progress on the Physics Design of the C-ADS Injector Scheme I

rfq, linac, focusing, ion-source

3863

Z. Li, P. Cheng, H. Geng, C. Meng, H.F. Ouyang, B. Sun, J.Y. Tang, F. Yan, Z. Yang
IHEP, Beijing, People's Republic of China

Funding: Surported by China ADS Project
The China ADS (C-ADS) driver linac is composed of two parallel 10 MeV injectors and a main linac which boosts the beam further to 1.5 MeV. There are two design schemes for the injectors based on different working frequency and superconducting cavity structures and are under developing at the same time on IHEP and IMP. The Injector Scheme I, which is proposed by IHEP, works at 325 MHz, the same frequency of the main linac, and superconducting Spoke cavities with geometry beta of 0.12, the same type of cavity as the main linac too, are applied after the RFQ. In this paper, the latest progress on physics design will be presented.

THPWO044

Error Analysis and Beam Loss Control in C-ADS Main Linac

linac, simulation, emittance, solenoid

3866

C. Meng, Z. Li, J.Y. Tang, F. Yan
IHEP, Beijing, People's Republic of China

The China ADS (C-ADS) driver linac is defined to deliver a CW proton beam of 1.5 GeV in energy and 10 mA in current. To meet the extremely high reliability and availability, it is very important and imperative to perform detailed error analysis to simulate the real machine, where the errors always exist. The error studies are by very intense macro-particle simulations by both Trace-Win and TRACK codes with space charge effects included. Through error analysis the proper closed-orbit correction scheme and the maximum tolerable hardware and alignment errors can be found. This paper presents the method to optimize the apertures of elements in the C-ADS main linac. According to the detailed sensitivity analysis of different errors, the static and dynamic errors for the main linac are proposed. The basic lattice scheme has also been re-optimized based on the error studies. The correction scheme is also described, and with the correction scheme the residual orbit can be controlled very well. The influence of the correctors and BPM failures on the correction scheme is also studied.

THPWO047

The LLRF Measurement and Analysis of the SSC-LINAC RFQ

rfq, linac, LLRF, simulation

3875

G. Liu, J.E. Chen, S.L. Gao, Y.R. Lu, Z. Wang, X.Q. Yan, K. Zhu
PKU, Beijing, People's Republic of China
X. Du, Y. He, G. Pan, Y.Q. Yang, X. Yin, Y.J. Yuan, Z.L. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

Funding: Supported by NSFC(11079001)
The manufacturing process of the SSC-LINAC RFQ went to end and the LLRF measurement has been done. The frequency of the RFQ is 53.557 MHz without tuning, which is not far from the design value 53.667 MHz. The unflatness of the field along the beam axis is less than ±4%, which meets the simulation results. The dipole field is in the acceptable margin as well. The frequency will be adjusted by tuning plungers in operation. In this paper, the field distribution along the cavity has been measured and compared with the modulated electrodes simulation. The difference and its influences on the beam transmission have been analyzed.

THPWO048

A CW High Charge State Heavy Ion RFQ for SSC-LINAC

rfq, ion, heavy-ion, simulation

3878

Y.R. Lu, J.E. Chen, S.L. Gao, G. Liu, Z. Wang, X.Q. Yan, K. Zhu
PKU, Beijing, People's Republic of China
Y. He, L.P. Sun, J.W. Xia, Y.Q. Yang, X. Yin, Y.J. Yuan, Z.L. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

Funding: Supported by NSFC 11079001
To improve the super heavy ion beam injection efficiency and supply high current heavy ion beam for Separated Sector Cyclotron, A CW RFQ for heavy ion with high charge state has been designed and manufactured in the last two years. This RFQ will operate at 53.667MHz, will accelerate super heavy ions such as 238U³⁴⁺ to 143keV/u. This paper will introduce the SSC-LINAC components, especially the RFQ beam dynamics, full length structure design, tuning and cooling method. Furthermore RF system and RF commissioning with full power for the RFQ power cavity will also be presented.

THPWO056

A 5.3 MeV/U, 200MHz APF DTL for Carbon Ions as an Injector of Medical Synchrotron

synchrotron, focusing, emittance, DTL

3890

P. Jiang, Y.J. Yuan
IMP, Lanzhou, People's Republic of China

A new low energy medium frequency DTL for 12C⁵⁺ with alternative phase focusing method (APF), which has advantage in compact space and low cost, was designed as an injector of medical synchrotron. There is no conventional focusing elements in the APF DTL, and transversal focusing is realized using RF field by varying synchronous phase instead. The envelopes of beam size are presented and the emittance change of six-dimension phase space is shown. The simple method proposed by Y. Iwata was used to create synchronous phase array. Since the motion between transversal and longitudinal plains are coupled, the longitudinal acceptance of the DTL is not large.

THPWO062

Status of the RAON Accelerator Systems

target, ion, linac, ISOL

3898

D. Jeon
IBS, Daejeon, Republic of Korea

Funding: This work is made possible by the support of the Ministry of Science, ICT and Future Planning (MSIP) and the National Research Foundation (NRF) of the Republic of Korea.
The RAON is the heavy ion accelerator being built in Korea to build the In-flight Fragment (IF) and Isotope Separation On-Line (ISOL) facilities to support cutting-edge researches in various science fields. Superconducting linac with 200 MeV/u, 400 kW is the driver for the IF facility and the 70 MeV, 70 kW H⁻ cyclotron is the driver for the ISOL facility. These facilities are to provide high intensity stable beams and rare isotope beams for the users domestic and abroad. The design and prototyping efforts are under way such as superconducting cavities and magnets. Status of the RAON accelerator systems is presented.

THPWO063

The Early Stage of the Cavity Fabrication Process (ECT and furnace) for RAON

niobium, vacuum, superconducting-cavity, linac

3901

M.J. Joung, H.C. Jung, H.J. Kim
IBS, Daejeon, Republic of Korea

RAON is consist of three part about the acceleration line. These are SCL1, SCL2 and SCL3. SCL1 and SCL3 will be made from QWR (Qarter Wave Resonator) and HWR (Half Wave Resonator). And SCL2 will be made from SSR1 (Single Spoke Resonator) and SSR2 (Single Spoke Resonator). Accordingly, The RAON needs 48 QWR, 276 HWR, 88 SSR1 and 136 SSR2 to get the performance that we want. To accelerate the particle using lots of cavity, we have to make a process of cavity fabrication for RAON. We will compare to each process made from the other laboratories and to make the optimal process for RAON to get the performance that we want. And that process will consider the type of cavity and the purpose of the accelerator. I will introduce the early stage of the cavity fabrication process for RAON in this paper.

THPWO064

Superconducting Linac for the Rare Isotope Science Project

linac, cryomodule, ion, quadrupole

3903

H.J. Kim, H.J. Cha, M.O. Hyun, H.J. Jang, D. Jeon, J.D. Joo, M.J. Joung, H.C. Jung, Y.C. Jung, Y. Kim, M. Lee, G.-T. Park
IBS, Daejeon, Republic of Korea

Abstract The RISP (Rare Isotope Science Project) accelerator has been planned to study heavy ion of nuclear, material and medical science at the Institute for Basic Science (IBS). It can deliver ions from proton to Uranium. The facility consists of three superconducting linacs of which superconducting cavities are independently phased and operating at three different frequencies, namely 81.25, 162.5 and 325 MHz. Requirement of the linac design is especially high for acceleration of multiple charge beams. In this paper, we present the RISP linac design, the superconducting cavity and the requirements of beam diagnosics.

THPWO070

ESS DTL RF MODELIZATION: FIELD TUNING AND STABILIZATION

DTL, linac, target, quadrupole

3918

R. De Prisco
ESS, Lund, Sweden
M. Comunian, F. Grespan, A. Pisent
INFN/LNL, Legnaro (PD), Italy
A.R. Karlsson
Lund University, Lund, Sweden

The Radio Frequency (RF) design of Drift Tube Linac (DTL) of the European Spallation Source, ESS, has been defined in order to satisfy the accelerating field requirements of beam dynamic studies and to reduce peak field levels in the critical areas. The electro-magnetic field is stabilized with post-couplers. The cells geometries of the DTL are optimized to accommodate permanent magnet quadrupoles (PMQ), to get maximum shunt impedance, to meet the Moretti criterion at the low energy part and to facilitate the mechanical construction.

THPWO090

MEBT Design for the Front End Test Stand Project at RAL

quadrupole, lattice, diagnostics, emittance

3969

M. Aslaninejad, J.K. Pozimski, P. Savage
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

The Front End Test Stand (FETS) linear accelerator at Rutherford Appleton laboratory (RAL) will accelerate a 60 mA, 2 ms, 50 pps H⁻ beam up to 3 MeV. A new lattice design for the Medium Energy Beam Transport (MEBT) with a fast-slow chopping system is presented. Beam dynamic simulation has shown very good particle transmission in this new lattice with space charge effects included. The beam energy distribution on the beam choppers dumps is also calculated.

THPWO092

Update of Beam Optics and SRF Cavities for Project X

linac, cryomodule, solenoid, optics

3975

T.N. Khabiboulline, P. Berrutti, V.A. Lebedev, A. Lunin, T.H. Nicol, J.-F. Ostiguy, T.J. Peterson, L. Ristori, A. Saini, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

The Project X staging [1] requires reconsideration of the beam optics and thus, the SRF system for the 3 GeV CW linac of the Project X. The revised beam optics is presented in the paper as well as revised cavity design for SSR2 section and a new concept of the linac segmentation. The new versions for the Project X cryo-modules for the SSR2 section, low-beta 650 MHz section and high-beta 650 MHz section are discussed. The beam extraction scheme at 1 GeV is discussed also. [1] S. Holmes, “Project X News, Strategy, Meeting Goals,” 2012 Fall Project X Collaboration Meeting, 27-28 November 2012, Fermilab.

THPWO094

Electromagnetic and Multi-particle Beam Dynamics Modeling of 4-Rod RFQs

rfq, simulation, vacuum, quadrupole

3978

S.S. Kurennoy, R.W. Garnett, L. Rybarcyk
LANL, Los Alamos, New Mexico, USA

Detailed 3D modeling of the recently commissioned FNAL 4-rod RFQ was performed with the CST Studio Suite. The RFQ model is based on the CAD files used for its fabrication, which are imported in CST Studio. The electromagnetic (EM) analysis was done with MicroWave Studio (MWS) and the beam dynamics modeled with Particle Studio (PS) using the MWS-calculated fields. Realistic matched input CW beam distributions, generated externally with up to 10K particles per RF period and up to 70 RF periods long, are injected in the RFQ for PS simulations. The EM analysis reveals some interesting features of the RFQ fields; their origin and influence on the beam parameters is studied. In particular, the end-gap longitudinal field, which is usually not taken into account when an RFQ is designed with standard codes, can change the output beam energy. Our CST modeling results helped explain and successfully resolve some problems encountered in the FNAL RFQ commissioning. We plan to use a similar approach to evaluate a new 4-rod RFQ that will become a part of an upgraded front end of the LANSCE linac.

FRXBA01

Accelerator Technology - From Big Projects to Broad Application

superconducting-magnet, heavy-ion, superconducting-RF, ion

3986

A. Yamamoto
KEK, Ibaraki, Japan

Big projects with far-reaching technical goals seem to define technical parameters and test infrastructure performance. As such these are the 'drivers' of the technology and have a vital role and have application far beyond that originally foreseen. This talk will examine these links and propose strategies to best leverage them.

Slides FRXBA01 [13.721 MB]

FRXAB201

Status of CSNS Project

target, quadrupole, linac, dipole

3995

S. Fu, H. Chen, Y.W. Chen, H. Dong, S.X. Fang, K.X. Huang, W. Kang, J. Li, H.C. Liu, L. Ma, H.F. Ouyang, H. Qu, H. Sun, J.Y. Tang, C.H. Wang, Q.B. Wang, S. Wang, T.G. Xu, Z.X. Xu, C. Zhang, J. Zhang
IHEP, Beijing, People's Republic of China

The China Spallation Neutron Source (CSNS) accelerator is designed to accelerate proton beam pulses to 1.6 GeV at 25 Hz repetition rate, striking a solid metal target to produce spallation neutrons. The accelerator provides a beam power of 100 kW on the target in the first phase and then 500 kW in the second phase by increasing the average beam intensity 5 times while raising the linac output energy. The project construction has been formally launched in 2011 and it is planed to complete the project in March 2018. It is one of the high intensity proton accelerator projects in the world and it imposes a great challenge to Chinese accelerator community. This presentation will cover the status and challenges of the CSNS project.

Slides FRXAB201 [4.320 MB]