• G. Andonian, A.Y. Murokh, C. Pellegrini, S. Reiche, J.B. Rosenzweig, G. Travish
  UCLA, Los Angeles, California
• M. Babzien, I. Ben-Zvi, V. Litvinenko, V. Yakimenko
  BNL, Upton, Long Island, New York
• I. Boscolo, S. Cialdi, A.F. Flacco
  INFN-Milano, Milano
• M. Ferrario, L. Palumbo, C. Vicario
  INFN/LNF, Frascati (Roma)
• J.Y. Huang
  POSTECH, Pohang, Kyungbuk

The VISA II experiment entails use of a chirped beam to drive a high gain SASE FEL. The output radiation is diagnosed with a modified frequency resolved optical gating (FROG) technique. Sextupoles are implemented to correct the lonigtudinal aberrations affecting the high energy spread chirped beam during transport to the undulator. The double differential energy spectrum is measured with a pair of slits and a set of gratings. In this paper, we report on start-to-end simulations, radiation diagnostics, as well as intial experimental results; experimental methods are described.

• H. Bluem, A. Ambrosio, V. Christina, M.D. Cole, M. Falletta, D. Holmes, E. Peterson, J. Rathke, T. Schultheiss, A.M.M. Todd, R. Wong
  AES, Medford, NY
• I. Ben-Zvi, A. Burrill, R. Calaga, P. Cameron, X.Y. Chang, H. Hahn, D. Kayran, J. Kewisch, V. Litvinenko, G.T. McIntyre, T. Nicoletti, J. Rank, T. Rao, J. Scaduto, K.-C. Wu, A. Zaltsman, Y. Zhao
  BNL, Upton, Long Island, New York
• S.V. Benson, E. Daly, D. Douglas, H.F.D. Dylla, L. W. Funk, C. Hernandez-Garcia, J. Hogan, P. Kneisel, J. Mammosser, G. Neil, H.L. Phillips, J.P. Preble, R.A. Rimmer, C.H. Rode, T. Siggins, T. Whitlach, M. Wiseman
  Jefferson Lab, Newport News, Virginia
• I.E. Campisi
  ORNL, Oak Ridge, Tennessee
• P. Colestock, J.P. Kelley, S.S. Kurennoy, D.C. Nguyen, W. Reass, D. Rees, S.J. Russell, D.L. Schrage, R.L. Wood
  LANL, Los Alamos, New Mexico
• D. Janssen
  FZR, Dresden
• J.W. Lewellen
  ANL, Argonne, Illinois
• J.S. Sekutowicz
  DESY, Hamburg
• L.M. Young
  TechSource, Santa Fe, New Mexico

Funding: This work is supported by the Naval Sea Systems Command, the Office of Naval Research, the DoD Joint Technology Office, the Missile Defense Agency and the US Department of Energy.

Reliable, high-brightness, high-power injector operation is a critical technology issue for energy recovery linac drivers of high-power free electron lasers (FEL). Advanced Energy Systems is involved in three ongoing injector programs that target up to 0.5 Ampere current levels at emittance values consistent with the requirements of the FEL. One is a DC photocathode gun and superconducting RF (SRF) booster cryomodule. A 748.5 MHz injector of this type is being assembled and will be tested up to 100 mA at the Thomas Jefferson National Accelerator Facility (JLAB) beginning in 2007. The second approach being explored is a high-current normal-conducting RF photoinjector. A 700 MHz gun, presently under fabrication, will undergo thermal test in 2006 at Los Alamos National Laboratory (LANL). Finally, a half-cell 703.75 MHz SRF gun is presently being designed and will be tested to 0.5 Ampere at Brookhaven National Laboratory (BNL) in 2007. The status and projected performance for each of these injector projects is presented.

• I. Ben-Zvi, D. Kayran, V. Litvinenko
  BNL, Upton, Long Island, New York

Historically, the first demonstration of the FEL was in an amplifier configuration at Stanford University. There were other notable instances of amplifying a seed laser, such as the LLNL amplifier and the BNL ATF High-Gain Harmonic Generation FEL. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance a 100 kW average power FEL. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting energy recovery linacs combine well with the high-gain FEL amplifier to produce unprecedented average power FELs with some advantages. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department.