MOPB —  Poster Session   (10-Sep-12   15:50—17:50)
Paper Title Page
MOPB001 Emittance Control for Different FACET Beam Setups in the SLAC Linac 174
  • F.-J. Decker, W.S. Colocho, N. Lipkowitz, Y. Nosochkov, J. Sheppard, H. Smith, Y. Sun, M.-H. Wang, G.R. White, U. Wienands, M. Woodley, G. Yocky
    SLAC, Menlo Park, California, USA
  Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
The linac beam at SLAC requires different setups for different users at FACET (Facility for Advanced aCcelerator Experimental Tests) area, like highly compressed, intense bunches, or lower charge, long bunches. These require typically a lengthy tuning effort since with a energy-time correlation ("chirp") bunch transverse wakefield kicks can be compensated with dispersive trajectory oscillations and vice versa. Lowering the charge or changing the bunch length will destroy this delicate balance. Besides the typical steering to minimize BPMs (Beam Position Monitors) with correctors, we applied different techniques to try to localize beam disturbances like dispersion with phase changes, RF-kicks and RF quadrupole fields turning a klystron off and on, or varying the phase, and finally wakefield kicks with different beam intensities. It is also important to quantify BPM to quadrupole offsets with "bow-tie" plot and that the correctors give the expected kicks with orbit response matrix measurements.
MOPB002 Positron Injector Linac Upgrade for SuperKEKB 177
  • T. Kamitani, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, K. Furukawa, Y. Higashi, T. Higo, H. Honma, N. Iida, M. Ikeda, E. Kadokura, K. Kakihara, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, T. Mori, K. Nakao, T. Natsui, Y. Ogawa, S. Ohsawa, T. Shidara, A. Shirakawa, H. Sugimoto, T. Suwada, T. Takatomi, T. Takenaka, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou
    KEK, Ibaraki, Japan
  • D. Satoh
    TIT, Tokyo, Japan
  The KEKB B-factory is under an upgrade construction for the SuperKEKB. To achieve 40 times higher luminosity, the linac is required to inject electrons and positrons with higher intensities (e-: 1 nC → 5 nC, e+: 1 nC → 4 nC) and lower emittances (e-: 300 → 20 μm, e+: 2100 → 10 μm). This paper describes the upgrade scheme of the positron source. A new positron capture section will have larger transverse and energy acceptances by introducing a flux concentrator and large aperture L-band and S-band accelerating structures. Beam line layout and quadrupole focusing system will be rearranged for the enlarged beam acceptance. Beam optics is designed to be compatible for positron and electron beams with different energies and emittances. Pulsed quadrupoles and steering magnets are added for better flexibility in optics and orbit tuning. Parameter optimization of the positron source by optics calculation and particle tracking simulation is described.  
MOPB003 Recent Improvements to the Control of the CTF3 High-Current Drive Beam 180
  • B. Constance, R. Corsini, D. Gamba, P. Skowroński
    CERN, Geneva, Switzerland
  In order to demonstrate the feasibility of the CLIC multi-TeV linear collider option, the drive beam complex at the CLIC Test Facility (CTF3) at CERN is providing high-current electron pulses for a number of related experiments. By means of a system of electron pulse compression and bunch frequency multiplication, a fully loaded, 120 MeV linac is used to generate 140 ns electron pulses of around 30 Amperes. Subsequent deceleration of this high-current drive beam demonstrates principles behind the CLIC acceleration scheme, and produces 12 GHz RF power for experimental purposes. As the facility has progressed toward routine operation, a number of studies aimed at improving the drive beam performance have been carried out. Additional feedbacks, automated steering programs, and improved control of optics and dispersion have contributed to a more stable, reproducible drive beam with consequent benefits for the experiments.  
MOPB004 Design and Operation of a Compact 1 MeV X-band Linac 183
  • G. Burt, T.N. Abram, P.K. Ambattu, C. Lingwood
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • I. Burrows, T. Hartnett, J.P. Hindley, C.J. White
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • P.A. Corlett, A.R. Goulden, P.A. McIntosh, K.J. Middleman, Y.M. Saveliev, R.J. Smith
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  A compact 1 MeV linac has been produced at the Cockcroft Institute using X-band RF technology. The linac is powered by a high power X-band magnetron and has a 17 keV 200 mA thermionic gun with a focus electrode for pulsing. A bi-periodic structure with on-axis coupling is used to minimise the radial size of the linac and to reduce the surface electric fields.  
MOPB005 High Gradient Operation of 8 GeV C-Band Accelerator in SACLA 186
  • T. Inagaki, C. Kondo, Y. Otake, T. Sakurai
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  SACLA (SPring-8 angstrom compact free electron laser) is the X-ray free electron laser (XFEL) facility. In order to shorten the 8 GeV accelerator length, a C-band (5712 MHz) accelerator was employed. Since the accelerating gradient of C-band accelerating structure is 35 MV/m in nominal, the active accelerator length is 230 m. In total, 64 klystrons, 64 pulse compressors, and 128 accelerating structures are used. In order to withstand the high surface field (~ 100 MV/m), and to reduce the amount of dark current, which decreases the demagnetization effect of undulators, the accelerating structures are carefully fabricated in the factory. After high power RF conditioning of 500 hours, the beam commissioning was started in February 2011. For night time of the commissioning, we continued the RF conditioning. The RF breakdown rate of the structure was steadily decreased. Now we operate the accelerator with the beam energy as much as 8.3 GeV, and the accelerating gradient of 37 MV/m in average. We found the amount of dark current is small enough. So far no trouble occurred in C-band RF components of 64 sets.  
MOPB007 Study of Microbunching Instabilitity in the Linac of the Shanghai Soft X-Ray Free Electron Laser Facility 189
  • D. Huang, Q. Gu, M. Zhang
    SINAP, Shanghai, People's Republic of China
  The microbunching instability in the LINAC of a FEL facility has always been an issue which may degrade the quality of the electron beam. As the result, the whole facility may not be working properly. Shanghai soft X-ray FEL project (SXFEL), which is planned to start construction by the end of 2012, will be the first X-ray FEL facility in China. In this article, detailed study will be given based on the physical design of the facility to gain better understanding and control over the possible microbunching instability in SXFEL, which is critical to the success of the project. Moreover, the contribution of the possible plasma effects to the instability will also be studied by modifying the physical model of the longitudinal space charge (LSC) impedance.  
MOPB011 Photoinjector of the EBTF/CLARA Facility at Daresbury 192
  • B.L. Militsyn, D. Angal-Kalinin, C. Hill, S.P. Jamison, J.K. Jones, J.W. McKenzie, K.J. Middleman, B.J.A. Shepherd, R.J. Smith, R. Valizadeh, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • N. Bliss, M.D. Roper
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  A description is given of a photoinjector designed for Compact Linear Advanced Research Accelerator (CLARA) and Electron Beam Test Facility (EBTF), which will eventually be used to drive a compact FEL. The photoinjector is based on a 2.5 cell S-band photocathode RF gun operating with a copper photocathode and driven by a third harmonic of Ti: Sapphire laser (266 nm) installed in dedicated thermally stabilized room. The injector will be operated with laser pulses with an energy of up to 2 mJ, a pulse duration of 100 fs and initially a repetition rate of 10 Hz, with the aim of increasing this eventually to 400 Hz. At a field gradient of 100 MV/m provided by a 10 MW klystron the gun is expected to deliver beam pulses with energy of up to 6 MeV. Duration and emittance of electron bunches essentially depend on the bunch charge and vary from 0.1 ps at 20 pC to 5 ps at 200 pC and from 0.2 to 2 mm mrad respectively. Additional compression of the electron bunches will be provided with a velocity bunching scheme. For thermal stability the low energy part of the injector is mounted on an artificial granite support.  
MOPB012 First RF Measurement Results for the European XFEL SC Cavity Production 195
  • A.A. Sulimov, P.B. Borowiec, V. Gubarev, J. Iversen, D. Kostin, G. Kreps, K. Krzysik, A. Matheisen, W.-D. Möller, D. Reschke, W. Singer
    DESY, Hamburg, Germany
  The first reference cavities (RCV) for the European XFEL Project are being tested within the collaboration of Research Instruments (RI), E. ZANON, IFJ-PAN and DESY: - production and warm RF measurements of cavities and their components at RI and ZANON; - surface preparation at DESY; - cold RF tests at DESY by IFJ-PAN. Purpose of the RCV is to establish a stable cavity fabrication and qualification of the surface preparation infrastructure at industry. All necessary RF measurements were done, starting with mechanical fabrication in 2011, till the tuning and cold cavity RF tests in 2012. We present the first results of RF measurements within RCV production for the European XFEL.  
poster icon Poster MOPB012 [1.843 MB]  
MOPB013 Experimental Results on the PHIL Photo-injector Test Stand at LAL 198
  • R. Roux, F. Blot, J. Brossard, C. Bruni, S. Cavalier, J-N. Cayla, V. Chaumat, M. El Khaldi, A. Gonnin, P. Lepercq, E.N. Mandag, B. Mercier, H. Monard, C. Prevost, V. Soskov, A. Variola
    LAL, Orsay, France
  Since the first beam in November 2009 of the alphaX S-band RF gun, upgrades of the beamline have been carried out. Several YAG screens based transverse dimensions monitors have been installed as well as supplementary charge diagnostics. We will present a detailed experimental characterization of the RF gun performances such as emittance measurement using a solenoid scan and energy spread as a function of the RF phase. Most of the accelerator operation and experimental results have been carried out with a copper photo-cathode. PHIL being a test stand for photo-injectors, we have also tested a magnesium photo-cathode with the aim of higher charge per bunch thanks to its higher quantum efficiency. We will report on the results of this experiment. In May 2012, a new RF gun, the PHIN gun, will be installed. This gun which is also a S-band 2,5 cells is a copy of the one that LAL built for the CLIC Test Facility 3 at CERN. In the future, we plan to use this gun to produce a high charge up to 10nC with CsTe photo-cathodes introduced in the gun from a UHV transfer chamber. Preliminary tests and measurements of the beam produced by this gun with a copper photo-cathode will be presented.  
MOPB014 Electron Model of a Dogbone RLA with Multi-Pass Arcs 201
  • S.A. Bogacz, G.A. Krafft, V.S. Morozov, Y. Roblin
    JLAB, Newport News, Virginia, USA
  • K.B. Beard
    Muons. Inc., USA
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supported in part by USDOE STTR Grant DE-FG02-08ER86351
The design of a dogbone RLA with linear-field multi-pass arcs was earlier developed for accelerating muons in a Neutrino Factory and a Muon Collider. It allows for efficient use of expensive RF while the multi-pass arc design based on linear combined-function magnets exhibits a number of advantages over separate-arc or pulsed-arc designs. Such an RLA may have applications going beyond muon acceleration. This paper describes a possible straightforward test of this concept by scaling a GeV scale muon design for electrons. Scaling muon momenta by the muon-to-electron mass ratio leads to a scheme, in which a 4.35 MeV/c electron beam is injected in the middle of a 2.9 MeV/pass linac with two double-pass return arcs and is accelerated to 17.4 MeV/c in 4.5 passes. All spatial dimensions including the orbit distortion are scaled by a factor of 7.5, which arises from scaling the 200 MHz muon RF to a readily available 1.5 GHz. The footprint of a complete RLA fits in a 25x7 m area. The scheme utilizes only fixed field magnets for both injection and extraction. The hardware requirements are not very demanding making it straightforward to implement the scaled design using available equipment.
MOPB016 In-situ Measurement of Beam-induced Fields in the S-band Accelerating Structures of the Diamond Light Source linac 204
  • C. Christou
    Diamond, Oxfordshire, United Kingdom
  The Diamond pre-injector linac uses two 5.2 m DESY linac II-type accelerating structures to generate a 100 MeV electron beam suitable for injection into the booster synchrotron. The structures are powered independently by two high-power S-band klystrons and are designed to operate at 3 GHz. Higher order modes up to 14 GHz induced by beam in unpowered accelerating and bunching structures have been directly measured using directional couplers in the high-power waveguide network. These modes are compared with an electromagnetic simulation of the structures. The negative impact of higher-order wakes on the bunch trains used at Diamond is considered, and the use of the multipole field measurement for alignment of the beam to the structure is investigated.  
MOPB017 Integration of the European XFEL Accelerating Modules 207
  • E. Vogel, S. Barbanotti, J. Branlard, H. Brueck, S. Choroba, L. Hagge, K. Jensch, V.V. Katalev, D. Kostin, D. Käfer, L. Lilje, A. Matheisen, W.-D. Möller, D. Nölle, B. Petersen, J. Prenting, D. Reschke, H. Schlarb, M. Schmökel, J.K. Sekutowicz, W. Singer, H. Weise
    DESY, Hamburg, Germany
  • J. Świerbleski, P.B. Borowiec
    IFJ-PAN, Kraków, Poland
  • S. Berry, O. Napoly, B. Visentin
    CEA/DSM/IRFU, France
  • A. Bosotti, P. Michelato
    INFN/LASA, Segrate (MI), Italy
  • W. Kaabi
    LAL, Orsay, France
  • C. Madec
    CEA/IRFU, Gif-sur-Yvette, France
  • E.P. Plawski
    NCBJ, Świerk/Otwock, Poland
  • F. Toral
    CIEMAT, Madrid, Spain
  The production of the 103 superconducting accelerating modules for the European XFEL is an international effort. Institutes and companies from seven different countries (China, France, Germany, Italy, Poland, Russia and Spain), organized in 12 different work packages contribute with parts, capacity for work and facilities to the production of the modules. Currently the series production of the individual parts started or is approaching. Personnel are trained for the assembly and testing of parts and as well for the complete modules. Here we present an overview and the status of all these activities.  
MOPB018 Analyzing Surface Roughness Dependence of Linear RF Losses 210
  • C. Xu
    The College of William and Mary, Williamsburg, USA
  • M.J. Kelley, C.E. Reece
    JLAB, Newport News, Virginia, USA
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Topographic structure on Superconductivity Radio Frequency (SRF) surfaces can contribute additional cavity RF losses describable in terms of surface RF reflectivity and absorption indices of wave scattering theory. At isotropic homogeneous extent, Power Spectrum Density (PSD) of roughness is introduced and quantifies the random surface topographic structure. PSD obtained from different surface treatments of niobium, such as Buffered Chemical Polishing (BCP), Electropolishing (EP), Nano-Mechanical Polishing (NMP) and Barrel Centrifugal Polishing (CBP) are compared. A perturbation model is utilized to calculate the additional rough surface RF losses based on PSD statistical analysis. This model will not consider that superconductor becomes normal conducting at fields higher than transition field. One can calculate the RF power dissipation ratio between rough surface and ideal smooth surface within this field range from linear loss mechanisms.
MOPB020 LLRF System Improvement for HLS Linac Upgrade 213
  • G. Huang, D. Jia, K. Jin, H. Lin, Weishi, Zhou. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • Y. Liu
    USTC, Hefei, Anhui, People's Republic of China
  Funding: supported by NSFC-CAS Joint Fund, contract no. 11079034
The linac beam energy will be upgraded from 200 MeV to 800 MeV, in order to realize the full-energy injection of storage ring at Hefei Light Source. This paper introduces the improvement of linac LLRF system, which is composed of phase reference and driver signal transmission and distribution, auto-phasing system, phase reversal device for SLED. the LLRF prototype has been constructed, and the test results is described in the paper.
MOPB021 Bunch-by-bunch Phase Modulation for Linac Beam-loading Compensation 216
  • G. Huang, D. Jia, K. Jin, H. Lin, Weishi, Zhou. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • Y. Liu
    USTC, Hefei, Anhui, People's Republic of China
  Funding: supported by NSFC-CAS Joint Fund, contract no. 11079034
If the linac is loaded by a high current, long pulse multi-bunch beam, the energy of the beam drops with time during the pulse. The bunch phase modulation method is introduced to compensate the beam loading. In this method the beam phase in the RF accelerating filed is changed bunch-by-bunch, the beam energy gain in the RF filed gradually grows up, which cancels the drop due to beam loading. The relationship between the beam phase distribution and the linac parameters is calculated in this paper.
MOPB022 RF Characteristic Studies on the Whole Accelerating Structure for the BEPCII Linear Accelerator 219
  • S. Pei, M. Hou, X. Li, J.R. Zhang
    IHEP, Beijing, People's Republic of China
  • B.L. Wang
    SINAP, Shanghai, People's Republic of China
  An accelerating structure is one device to boost the particle energy. 2856 MHz 3 m long travelling wave disk-loaded accelerating structure is applied in BEPCII linac, its RF characteristics are mainly determined by the 84 regular cells located between the input and output couplers. Input and output couplers need to be included when the whole structure RF characteristics are simulated before fabrication; otherwise it would be difficult to obtain the travelling wave fields excited in the whole structure. If the real 3D couplers are modelled during the design process, a large amount of computer resources and time need to be used. However, if the redesigned azimuth symmetric coupler is used to replace the real 3D one during the simulation process, much less computer resources and time are required. With this method proposed here, the simulation results agree well with the theoretically calculated and experimentally measured ones.
MOPB023 Progress on the Design and Construction of the 100 MeV / 100 kW Electron Linac for the NSC KIPT Neutron Source 222
  • S. Pei, J. Cao, Y.L. Chi, B. Deng, C.D. Deng, H.S. Guo, D.Y. He, X. He, M. Hou, X.C. Kong, Q. Le, X. Li, J. Liu, R.L. Liu, W.B. Liu, K. Lv, C. Ma, H.Z. Ma, G. Pei, H. Song, L. Wang, S.H. Wang, X. Wang, Q. Yang, J. Yue, J.R. Zhang, F. Zhao, J.B. Zhao, J.X. Zhao, Z.S. Zhou
    IHEP, Beijing, People's Republic of China
  • M.I. Ayzatskiy, I.M. Karnaukhov, V.A. Kushnir, V.V. Mytrochenko, A.Y. Zelinsky
    NSC/KIPT, Kharkov, Ukraine
  • Y. Gohar
    ANL, Argonne, USA
  IHEP in China is designing and constructing a 100 MeV / 100 kW electron linac for NSC KIPT, which will be used as the driver of a neutron source based on a subcritical assembly. Recently, the physical design has been finalized. The chicane scheme instead of the RF chopper one has been selected. The mechanical design is on-going and will be finished in the very near future. The injector part of the machine has been installed in the experimental hall #2 of IHEP and is being commissioned and tested. The progress on the machine design and construction are reported, initial testing and commissioning results of the injector are also presented.
MOPB024 Beam Dynamics Simulation and Optimization for 10 MeV Superconducting e-Linac Injector for VECC-RIB Facility 225
  • A. Chakrabarti, S. Dechoudhury, V. Naik
    VECC, Kolkata, India
  • F. Ames, R.A. Baartman, Y.-C. Chao, R.E. Laxdal, M. Marchetto, L. Merminga, F. Yan
    TRIUMF, Vancouver, Canada
  • G. Goh
    SFU, Burnaby, BC, Canada
  Funding: This project is funded by Department of Atomic Energy, India
In the first phase of ongoing collaboration between VECC (India) and TRIUMF (Canada) a 10 MeV superconducting electron linac injector will be installed at VECC. This will constitute a 100 keV DC thermionic gun with grid delivering pulsed electron beam at 650 MHz. Owing to low energy from the gun, a capture cryo-module (CCM) consisting of two β = 1 single cell elliptical cavities (frequency = 1.3 GHz) will be inserted before a 9-cell β = 1 elliptical cavity that will provide acceleration to 10 MeV. The present paper depicts the beam dynamics simulation and optimization of different parameters for the injector with a realistic simulated beam emittance from the electron gun.
MOPB025 1ms Multi-bunch Electron Beam Acceleration by a Normal Conducting RF Gun and Superconducting Accelerator 228
  • M. Kuriki, S. Hosoda, H. Iijima
    HU/AdSM, Higashi-Hiroshima, Japan
  • H. Hayano, J. Urakawa, K. Watanabe
    KEK, Ibaraki, Japan
  • G. Isoyama, R. Kato, K. Kawase
    ISIR, Osaka, Japan
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • A. Kuramoto
    Sokendai, Ibaraki, Japan
  • K. Sakaue
    RISE, Tokyo, Japan
  Funding: Quantum Beam Project by MEXT, Japan
We perform electron beam generation and acceleration of 1 ms long pulse and multi-bunch format at KEK-STF (Superconducting Test Facility). The 1 ms long pulse beam is generated by a normal conducting photo-cathode L-band RF gun. The beam is boosted up to 40 MeV by a super-conducting accelerator. Aim of STF is to establish the super-conducting accelerator technology for ILC (International Linear Collider). The facility is concurrently used to demonstrate high brightness X-ray generation by inverse laser Compton scattering supported by MEXT Quantum Beam project. The RF gun cavity has been fabricated by DESY-FNAL-KEK collaboration. After conditioning process, a stable operation of the cavity up to 4.0 MW RF input with 1 ms pulse was achieved by keeping low dark current. 1 ms pulse generation and acceleration has been confirmed in March 2012. Quasi-monochromatic X-ray generation experiment by Laser-Compton will be carried out at STF from the next coming July. We report the latest status of STF.
MOPB026 TRIUMF/VECC e-Linac Injector Beam Test 231
  • R.E. Laxdal, F. Ames, Y.-C. Chao, K. Fong, C. Gong, A. Laxdal, M. Marchetto, W.R. Rawnsley, S. Saminathan, V.A. Verzilov, Q. Zheng, V. Zvyagintsev
    TRIUMF, Vancouver, Canada
  • J.M. Abernathy, D. Karlen, D.W. Storey
    Victoria University, Victoria, B.C., Canada
  • A. Chakrabarti, V. Naik
    VECC, Kolkata, India
  TRIUMF is collaborating with VECC on the design of a 10 MeV injector cryomodule to be used as a front end for a high intensity electron linac. A electron gun and low energy beam transport (LEBT) have been installed in a test area to act as the injector for the cryomodule test. The LEBT includes a wide variety of diagnostics to fully characterize the beam from the gun. A series of beam tests are being conducted during the stage installation. The test configuration details and results of beam tests will be presented.  
MOPB029 Commissioning of the X-Band Test Area at SLAC 234
  • C. Limborg-Deprey, C. Adolphsen, M.P. Dunning, S. Gilevich, C. Hast, R.K. Jobe, D.J. McCormick, A. Miahnahri, T.O. Raubenheimer, A.E. Vlieks, D.R. Walz, S.P. Weathersby
    SLAC, Menlo Park, California, USA
  Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.
The X-Band Test Area (XTA) is being assembled in the NLCTA tunnel at SLAC to serve as a test facility for new X-Band RF guns. The first gun to be tested is an upgraded version of the 5.6 cell, 200 MV/m peak field X-band gun designed at SLAC in 2003 for the Compton Scattering experiment run in ASTA [1]. The XTA beamline is equipped with diagnostics to measure both the longitudinal phase space and the transverse phase space properties of the beam after it has reached 100 MeV. We will review design choices and present some early commissioning results.
[1] A.E. Vlieks, et al. “Recent measurements and plans for the SLAC Compton X-ray source”, SLAC-PUB-11689, 2006. 10pp. Published in AIP Conf. Proc.807:481-490, 2006
MOPB030 Performance of First C100 Cryomodules for the CEBAF 12 GeV Upgrade Project 237
  • M.A. Drury, A. Burrill, G.K. Davis, J. Hogan, L.K. King, F. Marhauser, H. Park, J.P. Preble, C.E. Reece, A.V. Reilly, R.A. Rimmer, H. Wang, M. Wiseman
    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.
The Thomas Jefferson National Accelerator Facility is currently engaged in the 12 GeV Upgrade Project. The goal of the project is a doubling of the available beam energy of CEBAF from 6 GeV to 12 GeV. This increase in beam energy will be due primarily to the construction and installation of ten “C100” cryomodules in the CEBAF linacs. The C100 cryomodules are designed to deliver an average 108 MV each from a string of eight seven-cell, electropolished superconducting RF cavities operating at an average accelerating gradient of 19.2 MV/m. The new cryomodules fit in the same available linac space as the original CEBAF 20 MV cryomodules. Cryomodule production started in September 2010. Initial acceptance testing started in June 2011. The first two C100 cryomodules were installed and tested from August 2011 through October 2011, and successfully operated during the last period of the CEBAF 6 GeV era, which ended in May 2012. This paper will present the results of acceptance testing and commissioning of the C100 style cryomodules to date.
MOPB031 Vibration Response Testing of the CEBAF 12 GeV Upgrade Cryomodules 240
  • G.K. Davis, J. Matalevich, T. Powers, M. Wiseman
    JLAB, Newport News, Virginia, USA
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
The CEBAF 12 GeV upgrade project includes 80 new 7-cell cavities assembled into 10 cryomodules. These cryomodules were tested during production to characterize their microphonic response in situ. For several early cryomodules, detailed (vibration) modal studies of the cryomodule string were performed during the assembly process to identify the structural contributors to the measured cryomodule microphonic response. Structural modifications were then modeled, implemented, and verified by subsequent modal testing and in-situ microphonic response testing. Interim and final results from this multi-stage process will be reviewed.
MOPB032 Stabilization of the Beam Intensity in the Linac at the CTF3 CLIC Test Facility 243
  • A. Dubrovskiy
    JINR, Dubna, Moscow Region, Russia
  • B.N. Bathe, S. Srivastava
    BARC, Mumbai, India
  • F. Tecker
    CERN, Geneva, Switzerland
  A new electron beam stabilization system has been introduced in CTF3 in order to open new possibilities for CLIC beam studies in ultra-stable conditions and to provide a sustainable tool to keep the beam intensity and energy at its reference values for long term operations. The stabilization system is based on a pulse-to-pulse feedback control of the electron gun to compensate intensity deviations measured at the end of the injector and at the beginning of the linac. Thereby it introduces negligible beam distortions at the end of the linac and it significantly reduces energy deviations. A self-calibration mechanism has been developed to automatically configure the feedback controller for the optimum performance. The residual intensity jitter of 0.045% of the stabilized beam was measured whereas the CLIC requirement is 0.075%.  
MOPB033 High Power Coupler Test for TRIUMF E-linac SC Cavities 246
  • A.K. Mitra, Z.T. Ang, S. Calic, P.R. Harmer, S.R. Koscielniak, R.E. Laxdal, W.R. Rawnsley, R.W. Shanks
    TRIUMF, Vancouver, Canada
  TRIUMF has been funded to build an electron linac with a final energy of 50 MeV and 500 kW beam power using TESLA type 9 cell superconducting cavities operating at 1.3 GHz at 2 Kelvin. The e-linac consists of an electron gun, buncher cavity, injector cryomodule, and two main-linac cryomodules. The injector module has one 9-cell cavity whereas each of the accelerating main-linac cryomodules contains two 9-cell cavities. It is scheduled to install the injector and one main accelerating cryomodule by 2014. Six power couplers, each rated for 60 kW cw, have been procured for three cavities. The injector cryomodule will be fed by a 30 kW cw inductive Output Tube (IOT) and the accelerating cryomodule will be powered by a 290 kW cw klystron. In order to install the power couplers in the cavities, they are to be assembled and conditioned with high power rf source. A power coupler test station has been built and tests of two power couplers have began. A 30 kW IOT has been commissioned to full output power and it will be used for the power coupler test. In this paper, test results of the rf conditioning of the power couplers under pulse and cw mode will be described.  
MOPB034 Novel Technique of Suppressing TBBU in High-energy ERLs 249
  • V. Litvinenko
    BNL, Upton, Long Island, New York, USA
  Energy recovery linacs (ERLs) is emerging generation of accelerators promising revolutionize the fields of high-energy physics and photon sciences. One potential weakness of these devices is transverse beam-breakup instability, which may severely limit available beam current. In this paper I am presenting new idea [1] developed for high-energy ERL which could be used for eRHIC, LHeC and, potentially, ILC: a concept of using main ERL linacs and natural chromaticity to suppressing TBBU instabilities by simplifying an ERL lattice. As demonstration of this method, I present tow specific example of eRHIC and LHeC ERLs.
[1] V.N. Litvinenko, Chromaticity of the lattice and beam stability in energy recovery linacs, submitted to PR ST-AB
MOPB035 The Linear Accelerating Structure Development for HLS Upgrade 252
  • K. Jin, Y. Hong, G. Huang, D. Jia, S.C. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  Hefei Light Source (HLS) is mainly composed of an 800 MeV electron storage ring and a 200 MeV constant-impedance Linac functioning as its injector. A new Linac is developed in view of the Full Energy Injection and the Top-up Injection scheme will be adopted in the HLS upgrade. In this paper, an 800 MeV linear accelerating system construction, the constant-gradient structure design and the symmetry couplers consideration will be described in detail. The manufacture technology, the RF measurement, the high power test results and the accelerating system operation are presented.  
MOPB036 Feasibility Study of Short Pulse Mode Operation for Multi-turn ERL Light Source 255
  • T. Atkinson, A.V. Bondarenko, A.N. Matveenko, Y. Petenev
    HZB, Berlin, Germany
  The optics and simulation group at HZB are designing Germany’s future light source. Based on the emerging Energy Recovery Linac super conducting technology, the Femto-Science-Factory (FSF) will provide its users with ultra-bright photons of Angstrom wavelength at 6 GeV. The FSF is intended to be a multi-user facility and offer a wide variety of operation modes. A low emittance ~0.1 μm rad mode will operate in conjunction with a short-pulse ~10 fs mode. This paper highlights the physical limitations when trying to offer interchangeable modes and preserve beam high quality.  
MOPB037 Linac Optics Design for Multi-turn ERL Light Source 258
  • Y. Petenev, T. Atkinson, A.V. Bondarenko, A.N. Matveenko
    HZB, Berlin, Germany
  The optics simulation group at HZB is designing a multi-turn energy recovery linac-based light source. Using the superconducting Linac technology, the Femto-Science-Factory (FSF) will provide its users with ultra-bright photon beams of angstrom wavelength at 6 GeV. The FSF is intended to be a multi-user facility and offer a variety of operation modes. In this paper a design of transverse optic of the beam motion in the Linacs is presented. An important point in the optics design was minimization of the beta-functions in the linac at all beam passes to suppress beam break-up (BBU) instability.  
MOPB038 Single Shot Bunch-by-Bunch Beam Emittance Measurement of the SPring-8 Linac 261
  • Y. Shoji, K. Takeda
    LASTI, Hyogo, Japan
  Bunch by bunch emittance of a single shot beam from the SPring-8 electron linac was measured. The linac is operated as an injector to the electron storage ring, NewSUBARU. A high beam stability is required for the stable top-up injection into the ring with a small acceptance. We used the electron ring as a part of the measurement system. The electron beam from the linac was injected into the ring and circulated for many turns. The beam profiles were recorded by a dual-sweep streak camera using the visible light in the ring. The fast sweep separated the bunches in 1 ns macro pulse and the slow sweep separated the profiles at different revolutions. It enabled a multi-record of beam profiles in one camera frame. Betatron oscillation in the ring produced the phase space rotation for the reconstruction of the beam emittance. The ring parameters were optimized for the measurement because the beam storage was not necessary. A stability of the linac beam was evaluated from the shot by shot fluctuation of the emittance and the bunch structure. We also compared the emittances of a front bunch and a rear bunch in the same pulse.  
MOPB041 Advances in Beam Tests of Dielectric Based Accelerating Structures 264
  • A. Kanareykin, S.P. Antipov, J.E. Butler, C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • W. Gai
    ANL, Argonne, USA
  • V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  Funding: US Department of Energy
Diamond is being evaluated as a dielectric material for dielectric loaded accelerating structures. It has a very low microwave loss tangent, high thermal conductivity, and supports high RF breakdown fields. We report on progress in our recent beam tests of the diamond based accelerating structures of the Ka-band and THz frequency ranges. Wakefield breakdown test of a diamond-loaded accelerating structure has been carried out at the ANL/AWA accelerator. The high charge beam from the AWA linac (~70 nC, σz = 2.5 mm) was passed through a rectangular diamond loaded resonator and induce an intense wakefield. A groove is cut on the diamond to enhance the field. Electric fields up to 0.3 GV/m has been detected on the diamond surface to attempt to initiate breakdown. A surface analysis of the diamond has been performed before and after the beam test. Wakefield effects in a 250 GHz planar diamond accelerating structure has been observed at BNL/ATF accelerator as well. We have directly measured the mm-wave wake fields induced by subpicosecond, intense relativistic electron bunches in a diamond loaded accelerating structure via the dielectric wake-field acceleration mechanism.
MOPB042 On-line Dispersion Free Steering for the Main Linac of CLIC 267
  • J. Pfingstner, D. Schulte
    CERN, Geneva, Switzerland
  For future linear colliders as well as for light sources, ground motion effects are a severe problem for the accelerator performance. After a few minutes, orbit feedback systems are not sufficient to mitigate all ground motion effects and additional long term methods will have to be deployed. In this paper, the long term ground motion effects in the main linac of the Compact Linear Collider (CLIC) are analysed via simulation studies. The primary growth of the projected emittance is identified to originate from chromatic dilutions due to dispersive beam orbits. To counter this effect, an on-line identification algorithm is applied to measure the dispersion parasitically. This dispersion estimate is used to correct the beam orbit with an iterative dispersion free steering algorithm. The presented results are not only of interest for the CLIC project, but for all linacs in which the dispersive orbit has to be corrected over time.  
MOPB043 Detailed Analysis of the Long-Range Wakefield in the Baseline Design of the CLIC Main Linac 270
  • V.F. Khan, A. Grudiev
    CERN, Geneva, Switzerland
  The baseline design for the accelerating structure of the CLIC main linac relies on strong damping of transverse higher order modes (HOMs). Each accelerating cell is equipped with four damping waveguides that enables HOM energy to propagate to damping loads. Most of the HOMs decay exponentially with a Q-factor of about 10 however, there are modes with higher Q-factors. Though the amplitude of the high Q modes is nearly two orders of magnitude smaller than the dominating lowest dipole mode, their cumulative effect over the entire bunch train may be significant and dilute the beam emittance to unacceptable level. In this paper we report on an accurate calculation of the long-range wakefield and its overall effect on beam dynamics. We also discuss possible measures to minimise its effect in a tapered structure.  
MOPB045 Specifications of the Distributed Timing System for the CLIC Main Linac 273
  • A. Gerbershagen, A. Andersson, D. Schulte
    CERN, Geneva, Switzerland
  • P. Burrows
    JAI, Oxford, United Kingdom
  • F.Ö. Ilday
    Bilkent University, Bilkent, Ankara, Turkey
  The longitudinal phase stability of CLIC main and drive beams is a crucial element of CLIC design. In order to measure and to control the phase, a distributed phase monitoring system has been proposed. The system measures the beam phase every 900 m. The relative phase between the measurement points is synchronized with an external reference system via a chain of reference lines. This paper presents the simulations of error propagation in the proposed distributed monitoring system and the impact on the drive and main beam phase errors and the luminosity. Based on the results the error tolerances for the proposed system are detailed.  
MOPB046 A 10 MeV L-band Linac for Irradiation Applications in China 276
  • G. Pei, Y.L. Chi, M.H. Dai, D.Y. He, X. He, X. Li, J. Liu, C. Ma, X. Wang, X.W. Yang, C.H. Yu, F. Zhao, J. Zhao, Z.S. Zhou
    IHEP, Beijing, People's Republic of China
  • Y. Feng, H. Huang, S. Shi, E. Tang, X. Yang, Q. Yuan, Z. Zhu
    Institute of High Energy Physics (IHEP), People's Republic of China
  • Z. Li, X. Zhang
    Wuxi EL PONT Radiation Technology Ltd, Wuxi, People's Republic of China
  The electron linear accelerator has wide applications, and the demands are keeping growing for the irradiation applications in China. A high beam power 10 MeV L-band Linac has been developed recently as a joint venture of Institute of High Energy Physics and EL-PONT Company. The Thales TH2104U klystron, 3 A thermionic electron gun and three meter L-band disk-loaded constant impedance RF structure are adopted. A stable electron beam of 10 MeV, 40 kW has been obtained in the last May with a microwave to beam efficiency of about 65%. In this paper we will present the detailed design issues and beam commissioning.  
MOPB047 Applications of Compact Dielectric Based Accelerators 279
  • C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • M.E. Conde, W. Gai, J.G. Power
    ANL, Argonne, USA
  Important progress on the development of dielectric based accelerators has been made experimentally and theoretically in the past few years. One advantage of dielectric accelerators over the metallic counterparts is its compact size, which may attract some applications in industrial or medical accelerators. In this article, we discuss the design and technologies of dielectric based accelerators toward these needs.  
MOPB048 Linear Accelerator Based on Parallel Coupled Accelerating Structure 282
  • A.E. Levichev, A.M. Barnyakov, V.M. Pavlov
    BINP SB RAS, Novosibirsk, Russia
  • Y.D. Chernousov
    ICKC, Novosibirsk, Russia
  • V. Ivannikov, I.V. Shebolaev
    ICKC SB RAS, Novosibirsk, Russia
  Accelerating stand based on parallel coupled accelerating structure and electron gun is developed and produced. The structure consists of five accelerating cavities. The RF power feeding of accelerating cavities is provided by common exciting cavity which is performed from rectangular waveguide loaded by reactive pins. Operating frequency is 2450 MHz. Electron gun is made on the basis of RF triode. Linear accelerator was tested with different working regimes. The obtained results are following: energy is up to 4 MeV, accelerating current is up to 300 mA with pulse duration of 2.5 ns on the half of the width; energy is up to 2.5 MeV, accelerating current is up to 100 mA with pulse duration of 5 μs; energy is up to 2.5 MeV, accelerating current is up to 120 mA with pulse duration of 5 μs and beam capture of 100%. The descriptions of the accelerator elements are given in the report. The features of the parallel coupled accelerating structure are discussed. The results of the measuring accelerator’s parameters are presented.  
MOPB049 Design of Compact C-Band Standing-Wave Accelerator for Medical Radiotherapy 285
  • H. Yang, M.-H. Cho, W. Namkung
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • S.H. Kim
    ANL, Argonne, USA
  • J.-S. Oh
    NFRI, Daejon, Republic of Korea
  Funding: Work supported by POSTECH Physics BK21 Program.
We design a C-band standing-wave accelerator for an X-ray and electron source of medical radiotherapy. The accelerator system is operated two modes, using the X-ray and electron beams. Since two modes require different energy, the accelerator is capable of producing 6-MeV, 100-mA pulsed electron beams with peak 2-MW RF power, and 7.5-MeV, 50 mA electron beams with peak 2.5-MW RF power. The beam is focused by less than 1 mm without external magnets. The accelerating structure is a bi-periodic and on-axis-coupled structure with a built-in bunching section, which consists of 3 bunching cells, 14 normal cells and a coupling cell. It is operated with the π/2-mode standing-wave. The bunching cells are designed to enhance the RF phase focusing. Each cavity is designed by the MWS code within 3% inter-cell coupling. In this paper, we present design details of RF cavities and the beam dynamics.
MOPB051 Changing Attitude to Radiation Hazards and Consequent Opportunities for LINAC Applications 288
  • Y. Socol
    Falcon Analytics, Netanya, Israel
  High-energy LINACs unavoidably yield ionizing radiation. This fact makes them subject to strict regulations and considerably limits applications. During the last two decades the attitude to ionizing radiation hazards seems to become more balanced, as opposed to "radiophobia" of the Cold-War era. Scientifically, the linear no-threshold (LNT) model of radiation damage is more and more questioned. Moreover, the hypotheses of radiation hormesis - beneficial effect of low-dose radiation - is studied. While this scientific debate has not yet given fruit regarding radiation regulation and policy, we may expect this in near to middle term. Namely, the ALARA (as low as reasonably achievable) demand is anticipated to be substituted by some tolerance level, which in turn is anticipated to be very high according to the present standards. The presentation will review the present status of the radiation-hazard debate, and outline anticipated opportunities for LINAC applications, like compact designs and wider industrial outreach.  
MOPB052 Fermilab 1.3 GHz Superconducting RF Cavity and Cryomodule Program for Future Linacs 291
  • C.M. Ginsburg
    Fermilab, Batavia, USA
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The proposed Project X accelerator and the International Linear Collider are based on superconducting RF technology. As a critical part of this effort, Fermilab has developed an extensive program in 1.3 GHz SRF cavity and cryomodule development. This program includes cavity inspection, surface processing, clean assembly, low-power bare cavity tests and pulsed high-power dressed cavity tests. Well performing cavities have been assembled into cryomodules for pulsed high-power tests and will be tested with beam. In addition, peripheral hardware such as tuners and couplers are under development. The current status and accomplishments of the Fermilab 1.3 GHz activity will be described, as well as the R&D program to extend the existing SRF pulsed operational experience into the CW regime.
MOPB053 Non-destructive Inspections for SC Cavities 294
  • Y. Iwashita, Y. Fuwa, M. Hashida, K. Otani, S. Sakabe, S. Tokita, H. Tongu
    Kyoto ICR, Uji, Kyoto, Japan
  • H. Hayano, K. Watanabe, Y. Yamamoto
    KEK, Ibaraki, Japan
  Non-destructive Inspections play important roles to improve yield in production of high-performance SC Cavities. Starting from the high-resolution camera for inspection of the cavity inner surface, high resolution T-map, X-map and eddy current scanner have been developed. We are also investigating radiography to detect small voids inside the Nb EBW seam, where the target resolution is 0.1 mm. We are carrying out radiography tests with X-rays induced from an ultra short pulse intense laser. Recent progress will be presented.  
MOPB054 Test Results of Tesla-style Cryomodules at Fermilab 297
  • E.R. Harms, K. Carlson, B. Chase, D.J. Crawford, E. Cullerton, D.R. Edstrom, Jr, A. Hocker, M.J. Kucera, J.R. Leibfritz, O.A. Nezhevenko, D.J. Nicklaus, Y.M. Pischalnikov, P.S. Prieto, J. Reid, W. Schappert, P. Varghese
    Fermilab, Batavia, USA
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Commissioning and operation of the first Tesla-style Cryomodule (CM-1) at Fermilab was concluded in recent months. It has now been replaced by a second Tesla Type III+ module, RFCA002. It is the first 8-cavity ILC style cryomodule to be built at Fermilab and also the first accelerating cryomodule of the Advanced Superconducting Test Accelerator (ASTA). We report on the operating results of both of these cryomodules.
MOPB055 Development of Superconducting Radio-Frequency (SRF) Deflecting Mode Cavities and Associated Waveguide Dampers for the APS Upgrade Short Pulse X-Ray Project 300
  • J.P. Holzbauer, A. Nassiri, G.J. Waldschmidt, G. Wu
    ANL, Argonne, USA
  Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357.
The Advanced Photon Source Upgrade (APS-U) is a Department of Energy (DoE) funded project to increase the available x-ray beam brightness and add capability to enhance time-resolved experiments on few-ps-scale at APS. A centerpiece of the upgrade is the generation of short pulse x-rays (SPXs) for pump-probe time-resolved capability using SRF deflecting cavities[1]. The SPX project is designed to produce 1-2 ps x-ray pulses for some users compared to the standard 100 ps pulses currently produced. SPX calls for using superconducting rf (SRF) deflecting cavities to give the electrons a correlation between longitudinal position in the bunch and vertical momentum [2]. The light produced by this bunch can be passed through a slit to produce a pulse of light much shorter than the bunch length at reduced flux. The ongoing work of designing these cavities and associated technologies will be presented. This includes the design and prototyping of higher-order (HOM) and lower-order mode (LOM) couplers and dampers as well as the fundamental power coupler (FPC). This work will be given in the context of SPX0, a demonstration cryomodule with two deflecting cavities to be installed in APS in early 2014.
[1] A. Zholents, et al., NIM A 425, 385 (1999)
[2] A. Nassiri, et al., “ Status of the Short-Pulse X-Ray Project at the Advanced Photon Source,” IPAC 2012, New Orleans, LA, May 2012.
MOPB056 Multipacting Analysis of High-Velocity Superconducting Spoke Resonators 303
  • C.S. Hopper, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  Some of the advantages of superconducting spoke cavities are currently being investigated for the high-velocity regime. When determining a final, optimized geometry, one must consider the possible limiting effects multipacting could have on the cavity. We report on the results of analytical calculations and numerical simulations of multipacting electrons in superconducting spoke cavities and methods for reducing their impact.  
MOPB057 Mechanical Study of the First Superconducting Half-wave Resonator for Injector II of CADS Project 306
  • S. He, Y. He, S.C. Huang, F.F. Wang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao
    IMP, Lanzhou, People's Republic of China
  Funding: This work is Supported by the National Natural Science Foundation of China (Grant Agreement 91026001)
Within the framework of the China Accelerator-Driven Sub-critical Systems (CADS) project, Institute of Modern Physics (IMP) Chinese Academic of Sciences has proposed a 162.5 MHz Half-Wave Resonator (HWR) Superconducting cavity for low energy section (β=0.09) of high power proton linear accelerators as a new injector II for CIADS. For the geometrical design of superconducting cavities structure mechanical simulations are essential to predict mechanical eigenmodes and the deformation of the cavity walls due to bath pressure effects and the cavity cool-down. Additionally, the tuning analysis has been investigated to control the frequency against microphonics and Lorentz force detuning. Therefore, several RF, static structure, thermal and modal analysis with a three-dimensional Finite-Element Method (FEM) code Traditional ANSYS have been performed.
MOPB059 The Superconducting CH Cavity Development in IMP* 309
  • M.X. Xu, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, Z.J. Wang, J.W. Xia, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao
    IMP, Lanzhou, People's Republic of China
  Funding: Work supported by 91026001 Nature Science Foundation of China
The Cross-Bar H-type (CH) cavity is a multi-gap drift tube structure operated in the H21 mode [1]. The Institute of Modern Physics (IMP) has been doing research and development on this type of superconducting CH cavity which can work at the C-ADS (accelerator driver sub-critical system of China). A new geometry CH cavity has been proposed which have smaller radius. It’s suitable in fabrication, and it’s can reduce cost too .Detailed numerical simulations with CST MicroWave Studio have been performed. An overall surface reduction of 30% against the old structure seems feasible. A copper model CH cavity is being fabrication for validating the simulations and the procedure of fabricating niobium cavity.
MOPB060 RF Surface Impedance Characterization of Potential New Materials for SRF-based Accelerators 312
  • B. P. Xiao, G.V. Eremeev, H.L. Phillips, C.E. Reece
    JLAB, Newport News, Virginia, USA
  • M.J. Kelley, B. P. Xiao
    The College of William and Mary, Williamsburg, USA
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In the development of new superconducting materials for possible use in SRF-based accelerators, it is useful to work with small candidate samples rather than complete resonant cavities. The recently commissioned Jefferson Lab rf Surface Impedance Characterization (SIC) system* can presently characterize the central region of 50 mm diameter disk samples of various materials from 2 to 40 K exposed to RF magnetic fields up to 14 mT at 7.4 GHz. We report the measurement results from bulk Nb, thin film Nb on Cu and sapphire substrates, and thin film MgB2 on sapphire substrate provided by colleagues at JLab and Temple University. We also report on efforts to extend the operating range to higher fields.
* B.P. Xiao, et al., RSI, 2011. 82: p. 056104
MOPB061 The New 2nd Generation SRF R&D Facility at Jefferson Lab: TEDF 315
  • C.E. Reece, A.V. Reilly
    JLAB, Newport News, Virginia, USA
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The US Department of Energy has funded a near-complete renovation of the SRF-based accelerator research and development facilities at Jefferson Lab. The project to accomplish this, the Technical and Engineering Development Facility (TEDF) Project has completed the first of two phases. An entirely new 3,300 m2 purpose-built SRF technical work facility has been constructed and is being occupied in summer of 2012. All SRF work processes with the exception of cryogenic testing has been relocated into the new building. All cavity fabrication, processing, thermal treatment, chemistry, cleaning, and assembly work is collected conveniently into a new LEED-certified building. An innovatively designed 750 m2 cleanroom/chemrooms suite provides long-term flexibility for support of multiple R&D and construction projects as well as continued process evolution. The detailed characteristics of this perhaps first 2nd-generation SRF facility will be described.
MOPB062 A New Internal Optical Profilometry System for Characterization of RF Cavity Surfaces – CYCLOPS 318
  • C.E. Reece, A.D. Palczewski, H. Tian
    JLAB, Newport News, Virginia, USA
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Jefferson Lab has received and commissioned a new interferometric optical profilometer specifically designed to provide internal surface mapping of elliptical rf cavities. The CavitY CaLibrated Optical Profilometry System – CYCLOPS – provides better than 2 micron lateral resolution and 0.1 micron surface height resolution of programmatically selected locations on the interior surface of multi-cell cavities. The system is being used to provide detailed characterization of surface topographic evolution as a function of applied surface treatments and to investigate particular localized defects. We also intend to use the system for 3D mapping of actual interior rf surface geometry for feedback to structure design model and fabrication tooling. First uses will be illustrated. CYCLOPS was developed and fabricated by MicroDynamics Inc., Woodstock, GA, USA.
MOPB063 Superconducting RF Linac for eRHIC 321
  • S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, H. Hahn, D. Kayran, V. Litvinenko, G.J. Mahler, G.T. McIntyre, V. Ptitsyn, R. Than, J.E. Tuozzolo, W. Xu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh
    Stony Brook University, Stony Brook, USA
  Funding: Work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
eRHIC will collide high-intensity hadron beams from RHIC with 50-mA electron beam from a six-pass 30-GeV Energy Recovery Linac (ERL), which will utilize 704 MHz superconducting RF accelerating structures. This presentation describes the eRHIC SRF linac requirements, layout and parameters, 5-cell SRF cavity with a new HOM damping scheme, project status and plans.
MOPB064 Developing of Superconducting RF Guns at BNL 324
  • S.A. Belomestnykh, Z. Altinbas, I. Ben-Zvi, J.C. Brutus, D.M. Gassner, H. Hahn, L.R. Hammons, J.P. Jamilkowski, D. Kayran, J. Kewisch, V. Litvinenko, G.J. Mahler, G.T. McIntyre, D. Pate, D. Phillips, T. Rao, S.K. Seberg, T. Seda, B. Sheehy, J. Skaritka, K.S. Smith, R. Than, J.E. Tuozzolo, E. Wang, Q. Wu, W. Xu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, J. Dai, M. Ruiz-Osés, T. Xin
    Stony Brook University, Stony Brook, USA
  • C.H. Boulware, T.L. Grimm
    Niowave, Inc., Lansing, Michigan, USA
  • A. Burrill
    JLAB, Newport News, Virginia, USA
  • R. Calaga
    CERN, Geneva, Switzerland
  • M.D. Cole, A.J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A.M.M. Todd
    AES, Medford, NY, USA
  • X. Liang
    SBU, Stony Brook, New York, USA
  Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. The work at Niowave is supported by the US DOE under SBIR contract No. DE-FG02-07ER84861.
BNL is developing several superconducting RF guns for different applications. The first gun is based on a half-cell 1.3 GHz elliptical cavity. This gun is used to study generation of polarized electrons from GaAs photocathodes. The second gun, also of a half-cell elliptical cavity design, operates at 704 MHz and is designed to produce high average current electron beam for the ERL prototype from a multi-alkali photocathodes. The third gun is of a quarter-wave resonator type, operating at 112 MHz. This gun will be used for photocathode studies, including a diamond-amplified cathode, and to generate high charge, low repetition rate beam for the coherent electron cooling experiment. In this presentation we will briefly describe the gun designs, present recent test results and discuss future plans.
MOPB065 Impact of Trapped Magnetic Flux and Systematic Flux Expulsion in Superconducting Niobium 327
  • J.M. Vogt, J. Knobloch, O. Kugeler
    HZB, Berlin, Germany
  The intrinsic quality factor Q0 of superconducting cavities is known to depend on various factors like niobium material properties, treatment history and magnetic shielding. We already reported an additional impact of temperature gradients during the cool-down on the obtained Q0. We believe cooling conditions can influence the level of flux trapping and hence the residual resistance. For further studies we have constructed a test stand using niobium rods to study flux trapping. Here we can precisely control the temperature and approach Tc 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. Applying a similar procedure to a superconducting cavity could allow for reduction of the magnetic contribution to the surface resistance and result in a significant improvement of Q0.  
MOPB066 Alternative Approaches for HOM-Damped Cavities 330
  • B. Riemann, T. Weis
    DELTA, Dortmund, Germany
  • A. Neumann
    HZB, Berlin, Germany
  Funding: this work is partly funded by BMBF contract no. 05K10PEA
Elliptical cavities have been a standard in SRF linac technology for 30 years. We present another approach to base cell geometry based on Bezier splines, that leads to equal performance levels and is much more flexible in terms of optimization. Using the BERLinPro main linac as an example, a spline multicell cavity is designed with equal performance goals. For the damping of higher order modes (HOMs), the installation of waveguides at the ends of a multicell cavity is a common approach.
MOPB067 Results and Performance Simulations of the Main Linac Design for BERLinPro 333
  • A. Neumann, W. Anders, J. Knobloch
    HZB, Berlin, Germany
  • K. Brackebusch, T. Flisgen, T. Galek, K. Papke, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • B. Riemann, T. Weis
    DELTA, Dortmund, Germany
  Funding: this work is partly funded by BMBF contract no. 05K10PEA and 05K10HRC
The Berlin Energy Recovery Linac Project (BERLinPro) is designed to develop and demonstrate CW LINAC technology for 100-mA-class ERLs. High-current operation requires an effective damping of higher-order modes (HOMs) of the 1.3 GHz main-linac cavities. We have studied elliptical 7-cell cavities damped by on the whole five waveguides at both ends. Eigenmode computations for geometrical figures of merit show that the present design should allow successful CW linac operation at the maximum beam current of 100 mA/77 pC bunch charge. To verify the results, the external Q factors are compared to the results of S-Parameter simulations that are postprocessed by a pole-fitting technique. First results of scattering parameter measurement on a room-temperature aluminium model are discussed. An outlook presenting the possibilities of combined multi-cavity simulations is included.
MOPB069 Study of HPR Created Oxide Layer at Nb Surfaces 336
  • P.V. Tyagi
    Sokendai, Ibaraki, Japan
  • H. Hayano, S. Kato, T. Saeki, M. Sawabe
    KEK, Ibaraki, Japan
  The performance of superconducting radio frequency (SRF) niobium (Nb) cavities strongly depends on final surface condition. Therefore the surface preparation of these SRF cavities often becomes critical. The preparation of surface includes two steps; surface chemistry (in order to get a smooth surface) and cleaning/rinsing (in order to remove contaminants left after the surface chemistry). As high pressure rinsing (HPR) with ultra pure water (UPW) is most commonly used surface cleaning method after the surface chemistry, it's very interesting to characterize the Nb surfaces after HPR. Results of our surface characterization done by XPS (x-ray photoelectron spectroscopy) with depth profiling show the presence of a thicker oxide surface characterization results show the presence of a thicker oxide layer at Nb surface as an outcome of HPR. In this article, we report the production of oxide layer (FWHM thickness) based on different conditions such as the pressures and doses.  
MOPB070 Quality Control of Cleanroom Processing Procedures of SRF Cavities for Mass Production 339
  • R. Oweiss, K. Elliott, A. Facco, M. Hodek, I.M. Malloch, J. Popielarski, L. Popielarski, K. Saito
    FRIB, East Lansing, Michigan, USA
  Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
Quality control is a key factor in the success of SRF cavity mass production. This paper summarizes ongoing research at the Facility for Rare Isotope Beams FRIB to validate the quality assurance of SRF cavities meanwhile optimizing processing procedures for mass production. Experiments are conducted to correlate surface cleanliness for niobium surfaces with high pressure rinse time using β=0.085 quarter-wave resonators (QWR) cavities. Diagnostic devices; liquid particle counter, surface particle detector and TOC analyzer are used to monitor key parameters for quality control. Rinse water samples are collected during high pressure rinsing to measure liquid particle counts. The SLS 1200 Sampler is used to detect the presence of liquid particles of 0.2 microns and up to 1 micron to set standards for acceptable cleaning thresholds and optimize high pressure rinse time. The QIII+ surface particle detector is used to scan high electric field region for the β=0.085 QWR to ensure high pressure rinsing efficiency. The β=0.085 QWR RF testing data are analyzed and results are presented to demonstrate the correlation between attained acceleration gradients and surface cleanliness.
MOPB071 Process Developments for Superconducting RF Low Beta Resonators for the ReA3 LINAC and Facility for Rare Isotope Beams 342
  • L. Popielarski, C. Compton, L.J. Dubbs, K. Elliott, A. Facco, L.L. Harle, I.M. Malloch, R. Oweiss, J.P. Ozelis, J. Popielarski, K. Saito
    FRIB, East Lansing, USA
  Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE SC0000661.
The Facility for Rare Isotope Beams (FRIB) will utilize over 330 superconducting radio frequency (SRF) low beta cavities for its heavy ion driver linac. The SRF department will process and test all cavities prior to string assembly in the cleanroom. The baseline cavity surface and bulk niobium processing procedures have been established. The methods are being optimized for production process rate benchmarking. Additional processes are being developed to increase flexibility and reduce technical risks. This paper will describe procedure developments and experimental results. Topics include high temperature heat treatment for hydrogen degassing, selective chemical etching for cavity frequency tuning, low-temperature bake out and process quality control.
MOPB072 Multipole Expansion of the Fields in Superconducting High-Velocity Spoke Cavities 345
  • R.G. Olave, J.R. Delayen, C.S. Hopper
    ODU, Norfolk, Virginia, USA
  Multi-spokes superconducting cavities in the high-beta regime are being considered for a number of applications. In order to accurately model the dynamics of the particles in such cavities, knowledge of the fields off-axis are needed. We present a study of the multipoles expansion of the fields from an EM simulation field data for a two-spoke cavity operating at 325 MHz, β = 0.82 and 500 MHz, β = 1.  
MOPB073 Cold Testing of Superconducting 72 MHz Quarter-wave Cavities for ATLAS 348
  • M.P. Kelly, Z.A. Conway, S.M. Gerbick, M. Kedzie, R.C. Murphy, P.N. Ostroumov, T. Reid
    ANL, Argonne, USA
  A set of seven 72 MHz β=0.077 superconducting quarter-wave cavities for a beam intensity upgrade of the ATLAS heavy-ion accelerator has been completed. Cavities have been fabricated using the lessons learned from the worldwide effort to extend the performance of niobium cavities close to the limits of the material. Key developments include the use of electropolishing on the completed cavity and with a temperature control system substantially upgraded from that for elliptical-cell EP systems. Wire EDM, used instead of traditional niobium machining, appears to be effective in eliminating performance limiting defects near the weld seams. Hydrogen degassing at 600C after electropolishing permits practical acceleration at 2 Kelvin with Bpeak>120 mT and cavity voltages>5 MV/cavity.  
MOPB074 Thermo-Mechanical Simulations of the Frequency Tuning Plunger for the IFMIF Half-Wave Resonator 351
  • N. Bazin, P. Bosland, S. Chel, G. Devanz, N. Grouas, P. Hardy, J. Migne, F. Orsini, F. Peauger
    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. The frequency tuning system of the IFMIF HWR is an innovated system based on a capacitive plunger installed in the electric field region allowing a large tuning range. Following the cold test results obtained on HWR equipped with the first design of plunger in 2011*, it was decided to develop a new design of a fully-niobium plunger. The paper will present the development of the new plunger concepts and the thermo-mechanical simulations. For the mechanical simulations, the aim is to sufficiently deform the plunger to tune the cavity while staying in the elastic range of the niobium material. For the thermal simulations, all the non-linear properties of the materials and the effects of the RF fields are taken into account: thermal conductivity and surface resistance are depending on the temperature, RF fields computed with dedicated software are leading to thermal dissipations in the materials and the vacuum seal.
* F. Orsini et al., “Vertical tests preliminary results of the IFMIF cavity prototypes and cryomodule development”, SRF 2011, Chigaco, USA
MOPB077 Lorentz Force Detuning Compensation Studies for Long Pulses in ILC type SRF Cavities 354
  • N. Solyak, G.I. Cancelo, B. Chase, D.J. Crawford, D.R. Edstrom, Jr, E.R. Harms, Y.M. Pischalnikov, W. Schappert
    Fermilab, Batavia, USA
  Project-X 3-8 GeV pulsed linac is based on ILC type 1.3 GHz elliptical cavities. The cavity will operate at 25 MV/m accelerating gradient, but in contrast with XFEL and ILC projects the required loaded Q is much higher (Q=107) and RF pulse is much longer (~8ms). For these parameters Lorence force detuning (LFD) and microphonics should be controlled at the level <30 Hz. A new algorithm of LFD compensation, developed at Fermilab for ILC cavities was applied for Lorentz force compensation studies for 8ms pulses. In these studies two cavities inside TESLA-type cryomodule at Fermilab NML facility have been powered by one klystron. Studies done for different cavity gradients and different values of loaded Q demonstrated that required compensation are achievable. Detuning measurements and compensation results are presented.  
MOPB079 Normal Conducting Deflecting Cavity Development at the Cockcroft Institute 357
  • G. Burt, P.K. Ambattu, A.C. Dexter, C. Lingwood, B.J. Woolley
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • S.R. Buckley, P. Goudket, C. Hill, P.A. McIntosh, J.W. McKenzie, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  • A. Grudiev
    CERN, Geneva, Switzerland
  • R.M. Jones
    UMAN, Manchester, United Kingdom
  Funding: This work has been supported by STFC and the EU through FP7 EUCARD.
Two normal conducting deflecting structures are currently being developed at the Cockcroft Institute, one as a crab cavity for CLIC and one for bunch slice diagnostics on low energy electron beams for EBTF at Daresbury. Each has its own challenges that need overcome. For CLIC the phase and amplitude tolerances are very stringent and hence beamloading effects and wakefields must be minimised. Significant work has been undertook to understand the effect of the couplers on beamloading and the effect of the couplers on the wakefields. For EBTF the difficulty is avoiding the large beam offset caused by the cavities internal deflecting voltage at the low beam energy. Propotypes for both cavities have been manufactured and results will be presented.
MOPB080 Status of the C-Band RF System for the SPARC-LAB High Brightness Photoinjector 360
  • R. Boni, D. Alesini, M. Bellaveglia, G. Di Pirro, M. Ferrario, A. Gallo, B. Spataro
    INFN/LNF, Frascati (Roma), Italy
  • A. Mostacci, L. Palumbo
    URLS, Rome, Italy
  The high brightness photoinjector in operation at the SPARC-LAB facility of the INFN-LNF, Italy, consists of a 150 MeV S-band electron accelerator aiming to explore the physics of low emittance high peak current electron beams and the related technology. Velocity bunching techniques, SASE and Seeded FEL experiments have been carried out successfully. To increase the beam energy and improve the performances of the experiments, it was decided to replace one S-band travelling wave accelerating cavity, with two C-band cavities that allow to reach higher energy gain per meter. The new C-band system is in a well advanced development phase and will be in operation early in 2013. The main technical issues of the C-band system and the R&D activities carried out till now are illustrated in detail in this paper.  
MOPB081 Travelling Wave Accelerating Structures with a Large Phase Advance 363
  • V.V. Paramonov
    RAS/INR, Moscow, Russia
  The electrons acceleration is considered in higher pass bands of TM01 wave for disk loaded waveguide, resulting in the possibility of traveling wave accelerating structures with an operating field phase advance between 180 – 1260 degrees per cell. With an appropriate shape optimization and some additional elements in cells proposed traveling wave structures have small transverse dimensions and high RF efficiency of standing wave operation. Examples of proposed structures together with RF and dispersion properties are presented.  
MOPB082 RF Parameters of the TE - Type Deflecting Structure for S-Band Frequency Range 366
  • V.V. Paramonov, L.V. Kravchuk
    RAS/INR, Moscow, Russia
  • K. Flöttmann
    DESY, Hamburg, Germany
  Funding: in part RBFR N 12-02-0654-a
Effective compact deflecting structure* has been proposed for L-band frequency range preferably. RF parameters of this structure considered for S-band frequency range both for traveling and standing wave operation.
* -V. Paramonov, L. Kravchuk, INR, S. Korepanov. Effective Standing Wave RF Structure for Particle Beam Deflector. Proc. 2006 Linac Conference, p. 649
MOPB083 Operational experience with the FERMI@Elettra S-band RF System 369
  • A. Fabris, P. Delgiusto, F. Gelmetti, M.M. Milloch, A. Milocco, F. Pribaz, C. Serpico, N. Sodomaco, R. Umer, L. Veljak
    ELETTRA, Basovizza, Italy
  FERMI@Elettra is a single-pass linac-based FEL user-facility covering the wavelength range from 100 nm (12 eV) to 4 nm (310 eV) and is located next to the third generation synchrotron radiation facility Elettra in Trieste, Italy. The machine is presently under commissioning and the first FEL line (FEL-1) will be opened to the users by the end of 2012. The 1.5 GeV linac is based on S-band technology. The S-band system is composed of fifteen 3 GHz 45 MW peak RF power plants powering the gun, eighteen accelerating structures and the RF deflectors. The S-band system has been set into operation in different phases starting from the second half of 2009. This paper provides an overview of the performance of the system, discussing the achieved results, the strategies adopted to assure them and possible upgrade paths to increase the operability and safety margins of the system.  
MOPB084 Design of a C-band Disk-loaded Type Accelerating Structure for a Higher Pulse Repetition Rate in the SACLA Accelerator. 372
  • T. Sakurai, T. Inagaki, Y. Otake
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • H. Ego
    JASRI/SPring-8, Hyogo-ken, Japan
  The higher pulse repetition rate of the SACLA accelerator provides a higher rate of X-ray laser pulses to expand ability of user experiments, such as simultaneously providing the laser to several beamlines and reducing a measuring time in the experiment. Therefore, we studied on a C-band accelerating structure for a higher pulse rate above 120 pps than that of the present case of 60 pps. The designed structure adopts a TM01-2π/3 mode disk-loaded type with a quasi-constant gradient . Since higher repetition rate operation is inclined to increase a number of vacuum electrical discharges, it is required to reduce the surface electric field in the structure. We designed an ellipsoidal curvature shape around an iris aperture, which reduces the maximum surface field by 20%. Since the higher repetition rate also increases the heat load of the structure, in simulation, we optimized cooling channels to obtain acceptable frequency detuning. As the results of the design, an accelerating gradient of more than 40 MV/m will be expected, when an input RF power of 80 MW is applied to the structure. In this paper, we report the design of the C-band accelerating structure and its rf properties.  
MOPB086 The Nonresonant Perturbation Theory Based Field Measurement and Tuning of a Linac Accelerating Structure 375
  • W. Fang, Q. Gu, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  • D.C. Tong
    TUB, Beijing, People's Republic of China
  Assisted by the bead pull technique, the nonresonant perturbation theory is applied for measuring and tuning the field of the linac accelerating structure. The method is capable of making non-touch measurement, amplitude and phase diagnostics, real time mismatch feedback and field tuning. Main considerations on measurement system and of C-band traveling-wave structure are described, the bead pull measurement and the tuning of the C-band traveling-wave linac accelerating structure are presented.  
MOPB087 S-Band Loads for SLAC Linac 378
  • A. Krasnykh, F.-J. Decker
    SLAC, Menlo Park, California, USA
  • R.W. LeClair
    INTA, Santa Clara, USA
  Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515 and SBIR grant number DE-SC0007661
The S-Band loads on the current SLAC linac RF system were designed, in some cases, 40+ years ago to terminate 2-3 MW peak power into a thin layer of coated Kanthal material as the high power absorber [1]. The technology of the load design was based on a flame-sprayed Kanthal wire method onto a base material. During SLAC linac upgrades, the 24 MW peak klystrons were replaced by 5045 klystrons with 65+ MW peak output power. Additionally, SLED cavities were introduced and as a result, the peak power in the current RF setup has increased up to 240 MW peak. The problem of reliable RF peak power termination and RF load lifetime required a careful study and adequate solution. Results of our studies and three designs of S-Band RF load for the present SLAC RF linac system is discussed. These designs are based on the use of low conductivity materials.
[1] “The Stanford Two-Mile Accelerator”, p. 376-381, R. B. Neal, General Editor, 1968, W. A. Benjamin, Inc., NY Amsterdam
MOPB088 Fabrication Tests for IMP 162.5 MHz RFQ 381
  • B. Zhang
    IMP, Lanzhou, People's Republic of China
  The RFQ for one of front ends of C-ADS is designed. The frequency of the RFQ is 162.5 MHz and the energy is 2.1 MeV. The beam intensity is 15 mA and it works at CW mode. Because of low frequency, the four-wing structure is big size. It makes fabrication will take more risks. Therefore, four fabrication testing were planned and done to minimize the technic risks. The description about fabrication and testing results are presented in the paper.  
MOPB089 X-Ray Local Energy Spectrum Measurement at Tsinghua Thomson Scattering X-Ray Source (TTX) 383
  • Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, H. Zha, Z. Zhang
    TUB, Beijing, People's Republic of China
  Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.  
MOPB090 FRIB Technology Demonstration Cryomodule Test 386
  • J. Popielarski, E.C. Bernard, S. Bricker, S. Chouhan, C. Compton, A. Facco, A. Fila, L.L. Harle, M. Hodek, L. Hodges, S. Jones, M. Leitner, D. R. Miller, S.J. Miller, D. Morris, R. Oweiss, J.P. Ozelis, L. Popielarski, K. Saito, N.R. Usher, J. Weisend, Y. Zhang, S. Zhao, Z. Zheng
    FRIB, East Lansing, USA
  • M. Klaus
    Technische Universität Dresden, Dresden, Germany
  A Technology Demonstration Cryomodule (TDCM) has been developed for a systems test of technology being developed for FRIB. The TDCM consists of two half wave resonators (HWRs) which have been designed for an optimum velocity of β=v/c=0.53 and a resonant frequency of 322 MHz. The resonators operate at 2 K. A superconducting 9 T solenoid is placed in close proximity to one of the installed HWRs. The 9 T solenoid operates at 4 K. A complete systems test of the cavities, magnets, and all ancillary components is presented in this paper.
This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE SC0000661.
MOPB091 The Injector Cryomodule for the ARIEL e-Linac at TRIUMF 389
  • R.E. Laxdal, A. Koveshnikov, N. Muller, W.R. Rawnsley, G. Stanford, V. Zvyagintsev
    TRIUMF, Vancouver, Canada
  • M. Ahammed, M. Mondrel
    VECC, Kolkata, India
  The ARIEL project at TRIUMF includes a 50 MeV-10 mA electron linear accelerator (e-Linac) using 1.3 GHz superconducting technology. The accelerator is divided into three cryomodules including a single cavity injector cryomodule (ICM) and two accelerating cryomodules with two cavities each. The ICM is being built first. The ICM utilizes a unique top-loading box vacuum vessel. The shape allows the addition of a 4 K/2 K cryogenic unit that accepts near atmospheric LHe and converts to 2 K liquid inside the cryomodule. The cryomodule design is complete and in fabrication. The 4 K/2 K cryogenic unit has been assembled and tested in a test cryostat. The paper will describe the design of the cryomodule and the results of the cryogenic tests.  
MOPB093 The Upgraded Argonne Wakefield Accelerator Facility (AWA): a Test-Bed for the Development of High Gradient Accelerating Structures and Wakefield Measurements 392
  • M.E. Conde, D.S. Doran, W. Gai, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof
    ANL, Argonne, USA
  • S.P. Antipov, C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • E.E. Wisniewski
    Illinois Institute of Technology, Chicago, Illinois, USA
  Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
Electron beam driven wakefield acceleration is a bona fide path to reach high gradient acceleration of electrons and positrons. With the goal of demonstrating the feasibility of this concept with realistic parameters, well beyond a proof-of-principle scenario, the AWA Facility is currently undergoing a major upgrade that will enable it to achieve accelerating gradients of hundreds of MV/m and energy gains on the order of 100 MeV per structure. A key aspect of the studies and experiments carried out at the AWA facility is the use of relatively short RF pulses (15 – 25 ns), which is believed to mitigate the risk of breakdown and structure damage. The upgraded facility will utilize long trains of high charge electron bunches to drive wakefields in the microwave range of frequencies (8 to 26 GHz), generating RF pulses with GW power levels.
MOPB094 Simulation Study on the Longitudinal Bunch Shape Measurement by RF Chopper at J-PARC Linac 395
  • T. Maruta
    JAEA/J-PARC, Tokai-mura, Japan
  • M. Ikegami
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  A RF chopper is placed in the medium energy transport section (MEBT1) at J-PARC linac. The chopper is normally driven at synchronous phase of 0 degree to give a maximum deflection. The chopper has two RF gaps and both of them deflect a beam bunch horizontally while RF is on. In the MEBT1 section, while we have a transverse emittance monitor, there is no longitudinal monitor. It is hard to newly place a longitudinal beam monitor there due to space limitation. We conduct a simulation which studies on the usability of the chopper to a longitudinal beam monitor. When the synchronous phase of the chopper is ± 90 degree, the longitudinal beam profile is projected to horizontal beam distribution. In this presentation, we introduce simulation results.  
MOPB095 Design of MEBT for the Project X Injector Experiment at Fermilab 398
  • A.V. Shemyakin, C.M. Baffes, A.Z. Chen, Y.I. Eidelman, B.M. Hanna, V.A. Lebedev, S. Nagaitsev, J.-F. Ostiguy, R.J. Pasquinelli, D.W. Peterson, L.R. Prost, G.W. Saewert, V.E. Scarpine, B.G. Shteynas, N. Solyak, D. Sun, M. Wendt, V.P. Yakovlev
    Fermilab, Batavia, USA
  • T. Tang
    SLAC, Menlo Park, California, USA
  Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE
The Project X Injector Experiment (PXIE), a test bed for the Project X front end, will be completed at Fermilab at FY12-16. One of the challenging goals of PXIE is demonstration of the capability to form a 1 mA H beam with an arbitrary selected bunch pattern from the initially 5 mA 162.5 MHz CW train. The bunch selection will be made in the Medium Energy Beam Transport (MEBT) at 2.1 MeV by diverting undesired bunches to an absorber. This paper will present the MEBT scheme and describe development of its elements, including the kickers and absorber.
MOPB096 Beam Loss Mitigation in J-PARC Linac after the Tohoku Earthquake 401
  • M. Ikegami, Z. Fang, K. Futatsukawa, T. Miyao
    KEK, Ibaraki, Japan
  • Y. Liu
    KEK/JAEA, Ibaraki-Ken, Japan
  • T. Maruta, A. Miura, J. Tamura, G.H. Wei
    JAEA/J-PARC, Tokai-mura, Japan
  • H. Sako
    JAEA, Ibaraki-ken, Japan
  The beam operation of J-PARC linac was interrupted by the Tohoku earthquake in March 2011. After significant effort for its restoration, we have resumed the beam operation of J-PARC linac in December 2011. After resumption of beam operation, we have been suffering from beam losses which were not observed before the earthquake. Tackling with the beam loss issues, we have been reached the comparable beam power for user operation to the one before the earthquake. In this paper, we present the experience in the beam start-up tuning after the earthquake with emphasis on the beam loss mitigation efforts.  
MOPB098 Planning for Experimental Demonstration of Transverse Emittance Transfer at the GSI UNILAC through Eigen-Emittance Shaping 404
  • C. Xiao, O.K. Kester
    IAP, Frankfurt am Main, Germany
  • L. Groening
    GSI, Darmstadt, Germany
  The minimum transverse emittances achievable in a beam line are determined by the two transverse eigen-emittances of the beam. For vanishing interplane correlations they are equal to the transverse rms-emittances. Eigen-emittances are constants of motion for all symplectic beam line elements, i.e. (even tilted) linear elements. To allow for rms-emittance transfer, the eigen-emittances are changed by a non-symplectic action to the beam, preferably preserving the 4d-rms-emittance. Unlike emittance swapping the presented concept will allow transforming a beam of equal rms-emittances into a beam of different rms-emittances while preserving the 4d-rms-emittance. This contribution will introduce the concept for eigen-emittance shaping and rms-emittance transfer at an ion linac. The actual work status towards the experimental demonstration of the concept at the GSI UNILAC is presented.