• G.H. Welsh, M.P. Anania, C. Aniculaesei, E. Brunetti, R.T.L. Burgess, S. Cipiccia, D. Clark, B. Ersfeld, M.R. Islam, R.C. Issac, D.A. Jaroszynski, G.G. Manahan, T. McCanny, G. Raj, A. J. W. Reitsma, R.P. Shanks, G. Vieux, S.M. Wiggins
  USTRAT/SUPA, Glasgow
• W.A. Gillespie
  University of Dundee, Nethergate, Dundee, Scotland
• M.J. Loos, S.B. van der Geer
  TUE, Eindhoven
• A. MacLeod
  UAD, Dundee

The Advanced Laser-Plasma High-Energy Accelerators towards X-rays (ALPHA-X) programme at the University of Strathclyde is developing laser-plasma wakefield accelerators to produce high energy, ultra-short duration electron bunches as drivers of radiation sources. Coherent emission will be produced in a free-electron laser by focussing the electron bunches into an undulator. To achieve net gain, a high peak current, low energy spread and low emittance are required. A high intensity ultra-short pulse from a 30 TW Ti:sapphire laser is focussed into a helium gas jet to produce femtosecond duration electron bunches in the range of 80 - 200 MeV. Beam transport is monitored using a series of Lanex screens positioned along the beam line. We present measurements of the electron beam energy spread as low as 0.7% (at 90 MeV) obtained using a high resolution magnetic dipole spectrometer. We also present pepper-pot measurements of the normalised transverse emittance of the order of 1 pi mm mrad. With further acceleration to 1 GeV, the beam parameters indicate the feasibility of a compact X-ray FEL with a suitable undulator.

• M.P. Anania, E. Brunetti, S. Cipiccia, D. Clark, R.C. Issac, D.A. Jaroszynski, G.G. Manahan, T. McCanny, A. J. W. Reitsma, R.P. Shanks, G.H. Welsh, S.M. Wiggins
  USTRAT/SUPA, Glasgow
• J.A. Clarke, M.W. Poole, B.J.A. Shepherd
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• M.J. de Loos, S.B. van der Geer
  Pulsar Physics, Eindhoven

Recent progress in developing laser-plasma accelerators is raising the possibility of a compact coherent radiation source that could be housed in a medium sized university department. Furthermore, since the duration of electron bunches from laser-plasma wakefield accelerators is determined by the relativistic plasma wavelength, radiation sources based on these accelerators can produce pulses with femtosecond durations. Beam properties from laser-plasma accelerators have been traditionally thought of as not being of sufficient quality to produce amplification. Our work shows that this is not the case. Here we present a study of the beam characteristics of a laser-plasma accelerator and the compact ALPHA-X (Advanced Laser Plasma High-energy Accelerators towards X-rays) FEL. We discuss the implementation of a focussing system consisting of a triplet of permanent magnet quadrupoles and a triplet of electromagnetic quadrupoles*. We will present a study of the influence of beam transport on FEL action in the undulator, paying particular attention to bunch dispersion in the undulator. This is an important step for developing a compact synchrotron source or a SASE free-electron laser.

*The design of these devices has been carried out using the GPT code, which considers space charge effects and allows a realistic estimate of electron beam properties along the beam line.