PSI, Villigen
In the planned PSI-XFEL facility, three FEL branches will supply coherent, ultra-bright, and ultra-short XFEL photons at wide wavelength range. FEL branch 1 will use a 6.0 GeV driving linac to generate hard X-rays from 0.1 nm to 0.3 nm, while FEL branch 2 is foreseen for X-rays from 0.3 nm to 1.0 nm. However, FEL branch 3 was designed to supply spatially as well as temporally coherent soft X-rays from 1.0 nm to 10 nm with the High-order Harmonic Generation based seeded HGHG scheme. To reach emittances of 0.2 mm.mrad and to squeeze consequently the whole facility within an 800 m long tunnel, PSI is presently developing an advanced low emittance gun (LEG) based on a 1 MV high gradient pulsed diode and field emission. The advanced LEG will be used to drive FEL branch 1 and 2, while an RF photoinjector will be used to drive the FEL branch 3. In this paper, we describe a CTF3 RF gun based injector, two bunch compressors, two diagnostic sections, and linacs for the PSI-XFEL FEL branch 3.
PSI, Villigen
Paul Scherrer Institute (PSI) is presently developing a low emittance electron source for the PSI-XFEL project. The electron gun consists of an adjustable diode configuration subject to pulses of 250 ns (FWHM) with amplitude up to 500 kV from an air-core transformer- based high-voltage pulser. The facility allows high gradient tests with different cathode configurations and emission processes (field emission and photo emission). In the first stage, the beamline is only made up of focussing solenoids followed by an emittance monitor. Selected beam characterization measurements, from photo-cathode operation driven by a 266 nm UV laser system delivering 4 uJ energy during 6.5 ps (FWHM), are presented and compared to the results of 3D particle tracking simulations.
