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Benson, S. V.

Paper Title Page
MOOAAB03 High Power Operation of the JLab IR FEL Driver Accelerator 83
 
  • S. V. Benson, K. Beard, G. H. Biallas, J. Boyce, D. B. Bullard, J. L. Coleman, D. Douglas, H. F.D. Dylla, R. Evans, P. Evtushenko, C. W. Gould, A. C. Grippo, J. G. Gubeli, D. Hardy, C. Hernandez-Garcia, C. Hovater, K. Jordan, J. M. Klopf, R. Li, S. W. Moore, G. Neil, M. Poelker, T. Powers, J. P. Preble, R. A. Rimmer, D. W. Sexton, M. D. Shinn, C. Tennant, R. L. Walker, G. P. Williams, S. Zhang
    Jefferson Lab, Newport News, Virginia
 
  Funding: This work supported by the Off. of Naval Research, the Joint Technology Off., the Commonwealth of Virginia, the Air Force Research Lab, Army Night Vision Lab, and by DOE Contract DE-AC05-060R23177.

Operation of the JLab IR Upgrade FEL at CW powers in excess of 10 kW requires sustained production of high electron beam powers by the driver ERL. This in turn demands attention to numerous issues and effects, including: cathode lifetime; control of beamline and RF system vacuum during high current operation; longitudinal space charge; longitudinal and transverse matching of irregular/large volume phase space distributions; halo management; management of remnant dispersive effects; resistive wall, wake-field, and RF heating of beam vacuum chambers; the beam break up instability; the impact of coherent synchrotron radiation (both on beam quality and the performance of laser optics); magnetic component stability and reproducibility; and RF stability and reproducibility. We discuss our experience with these issues and describe the modus vivendi that has evolved during prolonged high current, high power beam and laser operation.

 
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TUPMS062 National High Magnetic Field Laboratory FEL Injector Design Consideration 1323
 
  • P. Evtushenko, S. V. Benson, D. Douglas, G. Neil
    Jefferson Lab, Newport News, Virginia
 
  A Numerical study of beam dynamics was performed for two injector systems for the proposed National High Magnetic Field Laboratory at the Florida State University (FSU) Free Electron Laser (FEL) facility. The first considered a system consisting of a thermionic DC gun, two buncher cavities operated at 260 MHz and 1.3 GHz and two TESLA type cavities, and is very similar to the injector of the ELBE Radiation Source. The second system we studied uses a DC photogun (a copy of JLab FEL electron gun), one buncher cavity operated at 1.3 GHz and two TESLA type cavities. The study is based on PARMELA simulations and takes into account operational experience of both the JLab FEL and the Radiation Source ELBE. The simulations predict the second system will have a much smaller longitudinal emittance. For this reason the DC photo gun based injector is preferred for the proposed FSU FEL facility.  
TUPMS065 JLAMP: An Amplifier Based FEL in the JLab SRF ERL Driver 1329
 
  • K. Jordan, S. V. Benson, D. Douglas, P. Evtushenko, C. Hernandez-Garcia, G. Neil
    Jefferson Lab, Newport News, Virginia
 
  Funding: This work supported by the Off. of Naval Research, the Joint Technology Off., the Commonwealth of Virginia, the Air Force Research Lab, Army Night Vision Lab, and by DOE Contract DE-AC05-060R23177.

Notional designs for ERL-driven high average power free electron lasers often invoke amplifier-based architectures. To date, however, amplifier FELs have been limited in average power output to values several orders of magnitude lower than those demonstrated in optical-resonator based systems; this is due at least in part to the limited electron beam powers available from their driver accelerators. In order to directly contrast the performance available from amplifiers to that provided by high-power cavity-based resonators, we have developed a scheme to test an amplifier FEL in the JLab SRF ERL driver. We describe an accelerator system design that can seamlessly and non-invasively integrate a 10 m wiggler into the existing system and which provides, at least in principle, performance that would support high-efficiency lasing in an amplifier configuration. Details of the design and an accelerator performance analysis will be presented.

 
THOAC04 RMS Emittance Measurements Using Optical Transition Radiation Interferometry at the Jefferson Lab FEL 2645
 
  • M. A. Holloway, R. B. Fiorito, P. G. O'Shea, A. G. Shkvarunets
    UMD, College Park, Maryland
  • S. V. Benson, W. Brock, J. L. Coleman, D. Douglas, R. Evans, P. Evtushenko, K. Jordan, D. W. Sexton
    Jefferson Lab, Newport News, Virginia
 
  Funding: Office of Naval Research Joint Technology Office

Optical Transition Radiation Interferometry (OTRI) has proven to be effective tool for measuring rms beam divergence. We present rms emittance measurement results of the 115 MeV energy recovery linac at the Thomas Jefferson National Laboratories Free electron Laser using OTRI. OTRI data from both near field beam images and far field angular distribution images give evidence of two spatial and angular distributions within the beam. Using the unique features of OTRI we segregate the two distributions of the beam and estimate separate rms emittance values for each component.

 
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