UCLA, Los Angeles, California
ENEA C.R. Frascati, Frascati (Roma)
PSI, Villigen
Narrow bandwidth FEL operation is one of the main challenges for future FEL facilities. Several schemes have been proposed to obtain a narrower bandwidth than that achievable with self amplified spontaneous emission starting from shot-noise. In this work the properties of two such schemese (high gain harmonic generation and self-seeding) are investigated and compared taking into account several non-ideal beam effects, with particular attention paid to the effect of bandwidth broadening associated to non-linear longitudinal phase-space. The comparison between the two schemes has been carried out with numerical simulations performed with GENESIS 1.3 and PERSEO FEL codes using both an idealized beam and realistic beams obtained with start to end simulations.
PSI, Villigen
The X-ray FEL facility SwissFEL, currently planned at the Paul Scherrer Institut, is primarily based on the SASE operation of a hard (1-7 Å) and soft (7-70 Å) X-ray beamline. However the soft X-ray FEL beamline is foreseen to allow for seeding down to 1 nm. The intrinsic shot noise in the electron bunch demands excellent state-of-the-art seeding sources and strategies. This presentation discusses various seeding options for the PSI-XFEL and evaluates them regarding performance and risk of implementation.
PSI, Villigen
The Paul Scherrer Institute is currently proposing a X-ray Free-electron Laser facility operating in the wavelength range of 0.1 to 7 nm. The overall design aims for a compact layout and relies on a low emittance electron beam and short period undulator. As an initial step, a 250 MeV is currently under construction to demonstrate a high brightness electron beam sufficient for operating the SwissFEL. An extension of the 250 MeV injector is under construction to test additional key components for the SwissFEL. Those are prototypes of the in-vacuum undulator modules as well as the proof-of-principle demonstration of echo-enabled harmonic generation as a possible seeding option for the SwissFEL at 1 nm. The combination of seeding and prototype undulator module allows for saturation of the FEL at 50 nm and first experiments with FEL radiation at the PSI.
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
A powerful THz source is being considered for THz-pump / X-ray probe experiments at the planned SwissFEL. The source should deliver half-cycle pulses of less than 1 ps duration with an energy of 100 μJ in a focal region of 1 mm2. Design considerations and simulations for such a source fulfilling the challenging parameter combination will be presented.
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 currently planned X-ray facility at the Paul Scherrer Institut will span a wavelength range between 1 Ångstroem and 7 nm, distributed over 2 beamlines. The design aims for a compact layout with low electron beam energies and short undulator periods for the hard X-ray beamline. The resulting tolerances are the most stringent for the operation at the shortest wavelength of 1 Å. The tolerance study, presented here, distinguish the error sources between those of components within the undulator beam line (e.g. undulator field errors) and jitter in the electron beam parameters. The latter can be used as the figure of merits for defining the tolerance budget of the injector and linac.
PSI, Villigen
The proposed SwissFEL will provide both hard x-rays down to 1Å and soft x-rays with full polarization control with a rather small electron energy of 5.8GeV. This continues the strategy of the medium energy synchrotron facilities, namely the SLS. The U15 and UE40 undulators are based on the experience with small period, small gap in-vacuum undulators and of APPLE II type respectively but are optimized for FEL operation. The undulator design including room temperature versus cryogenic principle, field optimization, materials and the demands for a series production will be discussed.