From incoherent to coherent x-rays with ICS sources

We present the design and performance parameters for a compact x-ray light source (CXLS), which is presently under construction, based on inverse Compton scattering (ICS) of a high brightness electron bunch on a picosecond laser pulse. The flux and brilliance of this source are orders of magnitude beyond existing laboratory scale sources. The accelerator operates at a repetition rate of 1 kHz with 100 bunches of 100 pC charge, each separated by 5 ns, in each shot. The entire CXLS is a few meters in length and produces hard x-rays tunable over a wide range of photon energies. The scattering laser is a Yb:YAG solid-state amplifier producing 100 mJ pulses at 1030 nm. The laser pulse is frequency-doubled and coupled into a ringdown cavity to match the linac pulse structure. At a photon energy of 12.4 keV, the predicted x-ray flux is 5×1011 photons/second in a 5% bandwidth and the brilliance is 2×1012 photons/(secmm2mrad20.1%) with a RMS pulse length of 490 fs. Novel concepts for improving the performance of the CXLS with the generation of relativistic electron beams having current modulation at nanometer scale and below are also discussed. This tunable longitudinal modulation enables the production of coherent hard x-rays with ICS.

[1]  J. Ruan,et al.  Tunable subpicosecond electron-bunch-train generation using a transverse-to-longitudinal phase-space exchange technique. , 2010, Physical review letters.

[2]  D E Moncton,et al.  Intense superradiant x rays from a compact source using a nanocathode array and emittance exchange. , 2012, Physical review letters.

[3]  Claudio Pellegrini,et al.  Collective instabilities and high-gain regime in a free electron laser , 1984 .

[4]  Frederic V. Hartemann,et al.  Three-dimensional time and frequency-domain theory of femtosecond x-ray pulse generation through Thomson scattering , 2004 .

[5]  Germán Sciaini,et al.  REGAE: New Source for Atomically Resolved Dynamics , 2012 .

[6]  O. J. Luiten,et al.  How to realize uniform three-dimensional ellipsoidal electron bunches. , 2004, Physical review letters.

[7]  Jerome B. Hastings,et al.  Ultrafast Time-Resolved Electron Diffraction with Megavolt Electron Beams , 2006 .

[8]  Bruce E. Carlsten,et al.  Using an emittance exchanger as a bunch compressor , 2011 .

[9]  Emilio A. Nanni,et al.  Aberration corrected emittance exchange , 2015 .

[10]  Jinfeng Yang,et al.  Transmission-electron diffraction by MeV electron pulses , 2011 .

[11]  William Graves,et al.  COMPACT XFEL LIGHT SOURCE , 2013 .

[12]  Alexander W. Chao,et al.  Emittance and phase space exchange for advanced beam manipulation and diagnostics , 2011 .

[13]  P. Musumeci,et al.  Relativistic electron diffraction at the UCLA Pegasus photoinjector laboratory. , 2008, Ultramicroscopy.

[14]  Zhirong Huang,et al.  Transverse-to-longitudinal emittance exchange to improve performance of high-gain free-electron lasers. , 2006 .

[15]  R. Miller,et al.  Mapping atomic motions with ultrabright electrons: the chemists' gedanken experiment enters the lab frame. , 2014, Annual review of physical chemistry.

[16]  Yiping Feng,et al.  High-brightness X-ray free-electron laser with an optical undulator by pulse shaping. , 2013, Optics express.

[17]  S. G. Rykovanov,et al.  Narrowband inverse Compton scattering x-ray sources at high laser intensities , 2014, 1412.2659.

[18]  Gianluca Geloni,et al.  The European X-ray Free-Electron Laser , 2015 .

[19]  D. Ratner,et al.  First lasing and operation of an ångstrom-wavelength free-electron laser , 2010 .

[20]  David Pile,et al.  X-rays: First light from SACLA , 2011 .

[21]  J. Bisognano,et al.  Nearly copropagating sheared laser pulse FEL undulator for soft x-rays , 2013 .

[22]  Max Cornacchia,et al.  Transverse to longitudinal emittance exchange , 2002 .

[23]  William Graves,et al.  Nanometer Scale Coherent Current Modulation via a Nanotip Cathode Array and Emittance Exchange , 2014 .

[24]  J. Rosenzweig,et al.  Experimental generation and characterization of uniformly filled ellipsoidal electron-beam distributions. , 2008, Physical review letters.

[25]  Emilio A. Nanni,et al.  Nano-modulated electron beams via electron diffraction and emittance exchange for coherent x-ray generation , 2015, 1506.07053.

[26]  D. E. Moncton,et al.  Compact x-ray source based on burst-mode inverse Compton scattering at 100 kHz , 2014, 1409.6954.

[27]  G. Krafft,et al.  Spectral distributions of thomson-scattered photons from high-intensity pulsed lasers. , 2004, Physical review letters.

[28]  Ming Xie,et al.  Exact and variational solutions of 3D Eigenmodes in high gain FELs , 1999 .

[29]  A. Howie,et al.  Diffraction channelling of fast electrons and positrons in crystals , 1966 .

[30]  Tuo Li,et al.  Emission properties of body-centered cubic elemental metal photocathodes , 2015 .