• 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.