PSI, Villigen
The Paul Scherrer Institut is proposing an X-ray FEL facility, providing a wavelength range between 1 Angstrom to 7 nm. The major mode of operation is SASE with a supplemental seeding option for wavelength down to 1 nm. In addition a low charge operation of about 10 pC is considered to achieve single spike operation in the soft X-ray regime and thus overcoming the limitation of seeding sources at that wavelength. This presentation discusses the basic operation as well expected stability of the performance in energy and spectral power.
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.
PSI, Villigen
The X-ray FEL project at PSI involves the development of an injector complex that enables operation of a SASE FEL at 0.1 nm with permanent-magnet undulator and minimum beam energy. In order to extensively study the generation, transport and time compression of high brightness beams and to support the component developments necessary for the XFEL project, PSI is presently constructing a 250 MeV injector test facility. In the low energy region enough space has been reserved to accommodate complex electron source configurations while at high energy a 16 m diagnostic line will be used for projected and slice parameter characterization. The first installed electron source will be a 2.5 cell S-band RF-Photo injector, previously developed at CERN within the CTF program, which should provide a projected emittance below 0.4 mm mrad at 200 pC. Four S-band travelling wave cavities will boost the energy up to 270 MeV and a fourth harmonic X-band cavity will be used to linearize the longitudinal phasespace distribution in front of the magnetic compression chicane. In this paper we describe the overall accelerator facility with its main components and we discuss the expected beam performances.
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.