• S.G. Anderson, F. Albert, C.P.J. Barty, D.J. Gibson, F.V. Hartemann, D.P. McNabb, M. J. Messerly, B. Rusnak, M. Shverdin, C. Siders
  LLNL, Livermore, California
• S.G. Tantawi, A.E. Vlieks
  SLAC, Menlo Park, California

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

We present a compact, X-band, high-brightness accelerator design suitable for driving a precision gamma-ray source. Future applications of gamma-rays generated by Compton-scattering of laser and relativistic electron beams place stringent demands on the brightness and stability of the incident electron beam. This design identifies the beam parameters required for gamma-ray production, including position, and pointing stability. The design uses an emittance compensated, 11.4 GHz photo-gun and linac to generate 400 pC, 1-2 mm-mrad electron bunches at up to 250 MeV and 120 Hz repetition rate. The effects of jitter in the photo-cathode laser and RF power system are analyzed as well as structure and optic misalignments and wakefields. Finally, strategies for the mitigation of on-axis bremsstrahlung noise are discussed.

• D.J. Gibson, S.G. Anderson, C.P.J. Barty, S.M. Betts, F.V. Hartemann, M. J. Messerly, H.H. Phan, M. Shverdin, C. Siders
  LLNL, Livermore, California

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Recently, a drive laser for an 2.86 GHz rf photoinjector, designed to provide a pulse that has a flat temporal and spatial profile, has been built, commissioned, and put into service as part of the LLNL Compton-scattering source program. This laser is based on an all-fiber oscillator and front-end amplification system, and provides both the laser light to generate the electrons as well as the rf signal that is amplified to accelerate them. Now, a new 11.424 GHz photoinjector is being developed, which has required a revised design of for the laser system. The higher frequency has placed more stringent requirements on the synchronization stability, delivered pulse length, and pulse rise times to maintain the desired emittance. Presented here are the overall design and measured performance of the current system and a discussion of what changes are being made to address observed shortcomings and more demanding requirements to make the system ready for the next-generation Compton-scattering source.

• F.V. Hartemann, F. Albert, G.G. Anderson, S.G. Anderson, C.P.J. Barty, A.J. Bayramian, S.M. Betts, T.S. Chu, R.R. Cross, C.A. Ebbers, S.E. Fisher, D.J. Gibson, D.P. McNabb, M. J. Messerly, M. Shverdin, C. Siders
  LLNL, Livermore, California
• E.N. Jongewaard, S.G. Tantawi, A.E. Vlieks
  SLAC, Menlo Park, California
• A. Ladran
  LBNL, Berkeley, California
• V.A. Semenov
  UCB, Berkeley, California

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

A precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is under development at LLNL. High-brightness, relativistic electron bunches produced by the linac interact with a Joule-class, 10 ps laser pulse to generate tunable gamma-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. The source will be used to excite nuclear resonance fluorescence lines in various isotopes; applications include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status will be presented.

• D.H. Froula, J. Bonlie, L. Divol, S.H. Glenzer, P. Michel, J. Palastro, D. Price, J.E. Ralph, J.S. Ross, C. Siders
  LLNL, Livermore, California
• C.E. Clayton, C. Joshi, K.A. Marsh, A.E. Pak
  UCLA, Los Angeles, California
• B.B. Pollock, G.R. Tynan
  UCSD, La Jolla, California

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and DE-FG03-92ER40727, and LDRD 06-ERD-056

Recent laser wakefield acceleration experiments at the Jupiter Laser Facility, Lawrence Livermore National Laboratory, will be discussed where the Callisto Laser has been upgraded and has demonstrated 60 fs, 10 J laser pulses. This 150 TW facility is providing the foundation to develop a GeV electron beam and associated betatron x-ray source for use on the petawatt high-repetition rate laser facility currently under development at LLNL. Initial self-guided experiments have produced high energy monoenergetic electrons while experiments using a multi-centimeter long magnetically controlled optical plasma waveguide are investigated. Measurements of the electron energy gain and electron trapping threshold using 150 TW laser pulses will be presented.