PSI, Villigen
Diagnostics with a transverse spatial resolution in the order or even higher than the intrinsic limit of the traditional OTR light spot imaging techniques is required for high energy and low emittance electron beams by FEL driver linac. High resolution measurements of the beam transverse size can be performed by moving the radiation detection from the space of the electron transverse coordinates to the Fourier conjugate space of the radiation angular distribution. The development of such a new diagnostic technique is related to the experimental investigation of the beam transverse size effects in the angular distribution of the OTR spectral intensity. The status of the experimental investigation of such a phenomenon at the SwissFEL project and the main features of such a new diagnostic technique will be presented.
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.
Uni HH, Hamburg
DESY, Hamburg
PSI, Villigen
DELTA, Dortmund
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin
The Free-electron-laser at Hamburg (FLASH) operates in the Self-Amplified Spontaneous Emission (SASE) mode, delivering to users photons in the XUV wavelength range. The FEL seeding schemes promise to improve the properties of the generated radiation in terms of stability in intensity and time. Such an experiment using higher harmonics of an optical laser as a seed is currently under construction at FLASH. The installation of the XUV seeding experiment (sFLASH) is going to take place in fall 2009. This includes mounting of new variable-gap undulators upstream of the existing SASE-undulators, building the XUV-seed source as well as installation of additional photon diagnostics and electron beam instrumentation. In this contribution the layout of sFLASH will be discussed together with the technical design of its major components.
Uni HH, Hamburg
DESY, Hamburg
PSI, Villigen
DELTA, Dortmund
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin
Starting from next year, the technical feasibility of a direct seeding scheme at 30 and 13nm will be studied at the free-electron laser FLASH at DESY. During a major shutdown in order to upgrade the SASE-FEL facility, it is planned to install a HHG source, a new chain of 10 m variable gap undulators and a dedicated commissioning beamline for photon diagnostics and pilot time-resolved pump-probe experiments. Besides demonstrating successful seeding at short wavelength, the project aims for time resolution in the 10 fs range to study ultrafast processes by combining the naturally synchronized FEL and seed laser pulses. After the extraction of the radiation in a magnetic chicane, a short branch will accommodate intensity and beam monitors and a spectrometer. The intensity monitor detects scattered photons from a gold mesh on a shot-to-shot basis using micro-channel plates and XUV diodes. It is designed to detect photons several orders of magnitude apart in flux, i.e. spanning the wide range from the spontaneous emission up to the seeded FEL radiation at gigawatt power level. Simulations of this device are presented as well as test and calibration measurements carried out at FLASH.
