Advanced Concepts and Future Directions
Accel/Storage Rings 08: Linear Accelerators
Paper Title Page
MOP007 The Development Status of Compact Linear Accelerator in Korea 112
 
  • B.S. Lee, M. Won
    Korea Basic Science Institute, Busan, Republic of Korea
  • J.-K. Ahn
    Pusan National University, Pusan, Republic of Korea
  • T. Nakagawa
    RIKEN Nishina Center, Wako, Japan
 
  Funding: This work was supported by KBSI D30300 to M.S Won
The establishment of a compact linear accelerator is in progress by Korea Basic Science Institute. The main capability of this facility is the production of multiply ionized metal clusters and the generation of intense beams of highly charged ions for material, medical and nuclear physical research. To generate the intense beam of highly charged ions, we will develop an Electron Cyclotron Resonance Ion Source (ECRIS) using 28GHz microwaves. For this ECRIS, the designing of a superconducting magnet, microwave inlet, beam extraction, and plasma chamber were in progress. A superconducting magnet system have also being developed. In this presentation, I report the current status of our compact linear accelerator development and future plan.
 
 
MOP008 Upgrade of the Argonne Wakefield Accelerator Facility (AWA) and Commissioning of a New RF Gun for Drive Beam Generation 115
 
  • 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.
The AWA Facility is presently undergoing several upgrades that will enable it to further study wakefield acceleration driven by high charge electron beams. The facility employs an L-band photocathode RF gun to generate high charge short electron bunches, which are used to drive wakefields in dielectric loaded structures as well as in metallic structures (iris loaded, photonic band gap, etc). Several facility upgrades are underway: (a) a new RF gun with a higher quantum efficiency photocathode will replace the RF gun that has been used to generate the drive bunches; (b) the existing RF gun will be used to generate a witness beam to probe the wakefields; (c) three new L-band RF power stations, each providing 25 MW, will be added to the facility; (d) five linac structures will be added to the drive beamline, bringing the beam energy up from 15 MeV to 75 MeV. The drive beam will consist of bunch trains of up to 32 bunches spaced by 0.77 ns with up to 100 nC per bunch. The goal of future experiments is to reach accelerating gradients of several hundred MV/m and to extract RF pulses with GW power level.
 
 
MOP009 Status and Plans for a SRF Accelerator Test Facility at Fermilab 118
 
  • J.R. Leibfritz, R. Andrews, K. Carlson, B. Chase, M.D. Church, E.R. Harms, A.L. Klebaner, M.J. Kucera, S.L. Lackey, A. Martinez, S. Nagaitsev, L.E. Nobrega, J. Reid, M. Wendt, S.J. Wesseln
    Fermilab, Batavia, USA
  • P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
 
  Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
A superconducting RF accelerator test facility is being constructed at Fermilab. The existing New Muon Lab (NML) building is being converted for this facility. The accelerator will consist of an electron gun, injector, beam acceleration section consisting of 3 TTF-type or ILC-type cryomodules, multiple downstream beamlines for testing diagnostics and conducting various beam tests, and a high power beam dump. When completed, it is envisioned that this facility will initially be capable of generating a 810 MeV electron beam with ILC beam intensity. Expansion plans of the facility are underway that will provide the capability to upgrade the accelerator to a total beam energy of 1.5 GeV. In addition to testing accelerator components, this facility will be used to test RF power equipment, instrumentation, LLRF and controls systems for future SRF accelerators such as the ILC and Project-X. This paper describes the current status and overall plans for this facility.
 
 
MOP010 Resonance, Particle Stability, and Acceleration in the Micro-Accelerator Platform 121
 
  • J.C. McNeur, J.B. Rosenzweig, G. Travish, J. Zhou
    UCLA, Los Angeles, USA
  • R.B. Yoder
    Manhattanville College, Purchase, New York, USA
 
  Funding: US Defense Threat Reduction Agency
A micron-scale dielectric-based slab-symmetric accelerator is currently being designed and fabricated at UCLA. This Micro-Accelerator Platform (MAP) accelerates electrons in a 800nm wide vacuum gap via a resonant accelerating mode excited by a side-coupled optical-wavelength laser. Detailed results of particle dynamics and field simulations are presented. In particular, we examine various methods of achieving net acceleration and particle stability. Additionally, structural designs that produce accelerating fields synchronous with both relativistic and sub-relativistic electrons are discussed.
 
 
MOP011 Standing Wakefield Accelerator Based on Periodic Dielectric Structures 124
 
  • X. Wei, G. Andonian, J.B. Rosenzweig, D. Stratakis
    UCLA, Los Angeles, USA
 
  In recent years dielectric wakefield accelerators (DWA) have attracted significant attention for applications in high energy physics and THz radiation sources. However, one needs sufficiently short driving bunches in order to take advantage of the DWA's scaling characteristics to achieve high gradient and high frequency accelerating fields. Since a single large charge Q driving bunch is difficult to be compressed to the needed rms bunch length, a driving bunch train with smaller Q and small emittance, should be used instead for the DWA. In view of this senario, the group velocity of the excited wakefields needs to be decreased to nearly zero, so the electromagnetic energy does not vacate the structure during the bunch train. In this paper we propose a standing wakefield accelerator based on periodic dielectric structures, and address the difference between the proposed structure and the conventional DWA.  
 
MOP012 Ultra-High Gradient Compact S-Band Accelerating Structure 127
 
  • L. Faillace, R.B. Agustsson, P. Frigola, A.Y. Murokh
    RadiaBeam, Santa Monica, USA
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  • J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • V. Yakimenko
    BNL, Upton, Long Island, New York, USA
 
  Funding: Dept. of Energy DE-SC0000866
In this paper, we present the radio-frequency design of the DECA (Doubled Energy Compact Accelerator) S-band accelerating structure operating in the pi-mode at 2.856 GHz, where RF power sources are commonly available. The development of the DECA structure will offer an ultra-compact drop-in replacement for a conventional S-band linac in research and industrial applications such as drivers for compact light sources, medical and security systems. The electromagnetic design has been performed with the codes SuperFish and HFSS. The choice of the single cell shape derives from an optimization process aiming to maximize RF efficiency and minimize surface fields at very high accelerating gradients, i.e. 50 MV/m and above. Such gradients can be achieved utilizing shape-optimized elliptical irises, dual-feed couplers with the "fat-lip" coupling slot geometry, and specialized fabrication procedures developed for high gradient structures. The thermal-stress analysis of the DECA structure is also presented.
* V. Dolgashev, "Status of X-band Standing Wave Structure Studies at SLAC", SLAC-PUB-10124, (2003).
** C. Limborg et al., "RF Design of LCLS Gun", LCLS-TN-05-03 (2005).
 
 
MOP014 Status and Upgrades of the NLCTA for Studies of Advanced Beam Acceleration, Dynamics, and Manipulation 130
 
  • M.P. Dunning, C. Adolphsen, T.S. Chu, E.R. Colby, A. Gilevich, C. Hast, R.K. Jobe, C. Limborg-Deprey, D.J. McCormick, B.D. McKee, J. Nelson, T.O. Raubenheimer, K. Soong, G.V. Stupakov, Z.M. Szalata, D.R. Walz, F. Wang, S.P. Weathersby, M. Woodley, D. Xiang
    SLAC, Menlo Park, California, USA
 
  The Next Linear Collider Test Accelerator (NLCTA) is a low-energy electron accelerator (120 MeV) at SLAC that is used for ultra-high gradient X-band RF structure testing and advanced accelerator research. Here we give an overview of the current program at the facility, including the E-163 direct laser acceleration experiment, the echo-enabled harmonic generation (EEHG) FEL experiment, narrow-band THz generation, coherent optical transition radiation (COTR) studies, microbunching instability studies, and X-band structure testing. We also present the upgrades that are currently underway and some future programs utilizing these upgrades, including extension of the EEHG experiments to higher harmonics, and an emittance exchange experiment.  
 
MOP015 An X-band Gun Test Area at SLAC 133
 
  • C. Limborg-Deprey, C. Adolphsen, T.S. Chu, M.P. Dunning, C. Hast, R.K. Jobe, E.N. Jongewaard, A.E. Vlieks, D.R. Walz, F. Wang
    SLAC, Menlo Park, California, USA
  • S.G. Anderson, F.V. Hartemann, T.L. Houck, R.A. Marsh
    LLNL, Livermore, California, USA
 
  Funding: Work supported by the U.S. DOE Contract No. DE-AC03-76SF00515
The XTA (X-Band Test Area) is being assembled in the NLCTA tunnel of the SLAC National Laboratory to serve as a test facility for new RF guns. The first gun to be tested will be an upgraded version of the 5.6 cell, 200MV/m peak field X-band designed at SLAC in 2003 for the Compton Scattering experiment run in ASTA. This new version includes some features implemented in 2006 on the LCLS gun such as racetrack couplers, increased mode separation and elliptical irises. These upgrades were discussed in collaboration with LLNL since the same gun will be used as a driver for the LLNL Gamma-ray Source. Our beamline includes an X-band accelerating section which takes the electron beam up to 100 MeV and an electron beam measurement station. Other X-Band guns such as the UCLA Hybrid gun will be characterized at our facility.
 
 
MOP016 Preliminary Simulations of Plasma Wakefield Accelerator Experiments at FACET 136
 
  • W. An, C. Joshi, W. Lu, W.B. Mori
    UCLA, Los Angeles, California, USA
  • M.J. Hogan
    SLAC, Menlo Park, California, USA
  • C. Huang
    LANL, Los Alamos, New Mexico, USA
 
  Funding: This work is supported by USDoE under DE-FC02-07ER41500, DE-FG02-92ER40727 and NSF under NSF PHY-0904039, PHY-0936266.
Recent experiments on former facility FFTB at SLAC has demonstrated that a single electron beam driven Plasma Wakefield Accelerator (PWFA) can be produced with an accelerating gradient of 52 GeV/m over a meter-long scale*. If another electron bunch is properly loaded into such a wakefield, it will obtain a high energy gain in a short distance as well as a small energy spread. Such PWFA experiment with two bunches will be performed in FACET, which is a new facility at SLAC**. Simulation results show that with possible beam parameters in FACET the first electron bunch (with less current than that in the FFTB experiment) can still produce a meter-long plasma column with a density of 5x1016 cm-3 via field ionization when we use a gas with a lower ionization energy. The second electron bunch can have a 10 GeV energy gain with a very narrow energy spread. If a pre-ionized plasma is used instead of the neutral gas, the energy gain of the second bunch can be enhanced to 30 GeV.
* I. Blumenfeld et al., Nature 445, 741 (2007).
** M. J.Hogan, et al.,NewJ. Phys.12, 055030(2010).