• D.J. Dunning, N. Thompson
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• B.W.J. McNeil
  USTRAT/SUPA, Glasgow
• P.H. Williams
  Cockcroft Institute, Warrington, Cheshire

Start-to-end modelling of a SASE mode-locked FEL amplifier scheme [1] is presented using a superconducting re-circulating linac design[2]. Locking of the modes is achieved by modulating the electron beam energy at the mode frequency spacing. Previous studies [3] have shown that in a High Harmonic Generation (HHG) seeded mode-coupled FEL amplifier scheme (no electron beam energy modulation), although the attosecond pulse train structure of the seed is amplified through to saturation, temporal broadening of the individual pulses occurs. An HHG seeded mode-locked FEL amplifier scheme is modelled and it is seen that the temporal spikes of the HHG seed must be correctly phase-matched with the electron beam energy modulation for successful operation. By using a filtered HHG seed, which removes the seed’s attosecond pulse train structure, no such phase matching is required. Despite the absence of an initial attosecond pulse structure, a modal structure develops and is subsequently amplified to generate an attosecond pulse train with the good temporal coherence properties of the seed, significantly shorter individual pulse widths and higher peak powers than may be achieved in the other schemes.

[1] N.R. Thompson, B.W.J. McNeil, Phys. Rev. Lett. 100, 203901 (2008)
[2] P.H. Williams et al, WE5RF, 23rd PAC, Vancouver (2009)
[3] B.W.J. McNeil et al, MOCAU04, 30th Int. FEL Conf., Gyeongju (2008)

• P.H. Williams, D. Angal-Kalinin, S.L. Smith
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• R. Bartolini, I.P.S. Martin
  JAI, Oxford
• P.H. Williams
  Cockcroft Institute, Warrington, Cheshire

We describe a design for a two-pass recirculating 1.3 GHz superconducting linac as a driver for the suite of free-electron lasers proposed in the UK New Light Source project. The machine will deliver longitudinally compressed electron bunches with repetition rates of 1 kHz with an initial upgrade path to increase this to 1 MHz. A modular philosophy is employed to separate beam injection and extraction from a three stage compression scheme. Results show that the necessary high peak currents can be achieved whilst preserving beam quality.

• P.H. Williams, D. Angal-Kalinin, S.L. Smith
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• R. Bartolini, I.P.S. Martin
  JAI, Oxford
• P.H. Williams
  Cockcroft Institute, Warrington, Cheshire

We describe a design for a two-pass recirculating 1.3 GHz superconducting linac as a driver for the suite of free-electron lasers proposed in the UK New Light Source project. The machine will deliver longitudinally compressed electron bunches with repetition rates of 1 kHz with an initial upgrade path to increase this to 1 MHz. A modular philosophy is employed to separate beam injection and extraction from a three stage compression scheme. Results show that the necessary high peak currents can be achieved whilst preserving beam quality.

• S.L. Smith, C.D. Beard, R.K. Buckley, S.R. Buckley, P.A. Corlett, D.J. Dunning, P. Goudket, S.F. Hill, F. Jackson, S.P. Jamison, J.K. Jones, L.B. Jones, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, J.F. Orrett, P.J. Phillips, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, N. Thompson, A.E. Wheelhouse, P.H. Williams
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• K. Harada
  KEK, Ibaraki
• D.J. Holder, P. Weightman
  The University of Liverpool, Liverpool
• M. Surman
  STFC/DL/SRD, Daresbury, Warrington, Cheshire

ALICE (Accelerators and Lasers In Combined Experiments), a 35 MeV energy recovery linac based light source, is being commissioned and developed as an experimental R&D facility for a wide range of projects that could employ synchronized ultra-short (<1ps) electron bunches and light pulses. A suit of light sources includes an IR FEL, Compton backscattering (CBS) X-ray source, high power THz source and a multi-TW femtosecond laser. The full energy recovery and coherently enhanced, due to shortness of the electron bunches, THz radiation have been already demonstrated on ALICE. Completion of the first phase of the CBS x-ray source experiment and first lasing of the IR FEL by the end of 2009. Status of ALICE experimental facility and latest results on FEL, THz, and CBS development are reported in this paper.

• R. Bartolini, C. Christou, J.H. Han, I.P.S. Martin, J. Rowland
  Diamond, Oxfordshire
• D. Angal-Kalinin, F. Jackson, B.D. Muratori, P.H. Williams
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• M. Venturini
  LBNL, Berkeley, California

The New Light Source (NLS) project was launched in April 2008 by the UK Science and Technology Facilities Council (STFC) to consider the scientific case and develop a conceptual design for a possible next generation light source based on a combination of advanced conventional laser and free-electron laser sources. In this paper we present the results of the optimisation of a single pass superconducting LINAC as a driver for the the NLS FELs. The optimisation process requires the analysis of complicated electron beam dynamics in the presence of CSR, wakefields and space charge and has specifically taken into account the requirements for FEL operation in a seeded harmonic cascade scheme.

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