• Y. Kim, H.-H. Braun, T. Garvey, M. Pedrozzi, J.-Y. Raguin, S. Reiche, T. Schilcher, V. Schlott
  PSI, Villigen

Recently, several groups suggested a new FEL operation mode with low single bunch charge to generate sub-fs long longitudinal coherent XFEL photon pulses, so called single spike lasing mode. At PSI, we studied this mode to generate single spike XFEL photon beams at 1 nm and 0.1 nm. We report several critical issues which we found with such an operation mode, namely, ultra-tight RF jitter tolerances, alignment tolerances, and challenging beam diagnostic specifications for the stable single spike lasing mode.

Slides

• R. Ganter, B. Beutner, S. Binder, H.-H. Braun, M. Broennimann, M. Dach, T. Garvey, C.H. Gough, C.P. Hauri, M. Heiniger, R. Ischebeck, S. Ivkovic, Y. Kim, E. Kirk, F. Le Pimpec, K.B. Li, R. Luescher, P. Ming, A. Oppelt, M. Paraliev, M. Pedrozzi, J.-Y. Raguin, L. Rivkin, T. Schietinger, T. Schilcher, B. Steffen, S. Tsujino, A.F. Wrulich
  PSI, Villigen

In the frame of the SwissFEL project, an electron gun based on diode acceleration followed by a two cell RF cavity is under test at PSI. The diode consists of a photocathode / anode assembly and is driven with a voltage pulse of 500 kV maximum in 200 ns FWHM . The metal photocathode is illuminated by a Nd:YLF laser operating at 262 nm wavelength with a pulselength of 10 to 35 ps (FWHM) producing electron bunches of up to 200 pC. The distance from cathode to anode can be varied from 0 to 30 millimeters with a typical cathode field of 50 MV/m during the commissioning phase. Electrons leave the diode through an anode aperture and enter a two cells RF Cavity (1.5 GHz), which accelerates the beam to a maximum energy of 5 MeV. Beam characteristic measurements are presented and compared with simulations.