PSI, Villigen
The Paul Scherrer Institut is planning to construct a free electron laser covering the wavelength range of 1-70 Å. This project, “SwissFEL” will use a C-band radio-frequency linac of variable energy, 2.1 GeV to 5.8 GeV. The laser will be equipped with two undulator lines. A short period (15 mm) in-vacuum undulator, ‘Aramis’ will provide hard X-ray radiation in the range 1 Å to 7 Å. A 40 mm period APPLE-type undulator ‘Athos’ will provide wavelengths from 7 Å to 7 nm. The accelerator will employ an S-band RF photo-gun and an S-band injector providing a low normalized slice emittance (~ 0.3 mm-mrad @ 200 pC) beam of 450 MeV. The initial photo-current of 22 Amperes is increased to 2.7 kA through the use of two magnetic chicane bunch compressors. Acceleration to full energy is provided by twenty-six C-band RF “modules” each consisting of four, 2 m long, C-band structures. We will describe the status of the project and in particular the design of the accelerator. The beam dynamics simulations which have led us to our base-line design will be discussed and a description of the basic RF module will be given. A schedule for the project realization will also be presented.
* Submitted by T. Garvey on behalf of the SwissFEL project group
PSI, Villigen
Transverse beam trajectory control is of great importance for SwissFEL as the lasing strategy is based on a relatively low energy and low emittance beam compared with other X-FEL facilities, thus aiming at a reasonable construction cost and size of the facility. A study of beam based alignment and orbit feedback has been performed, and a trajectory correction scenario, which would fulfill the beam requirements as well as the hardware constraints, has been set up. The beam based alignment will be discussed for the linac and the undulator section separately because of the much tighter tolerance in the latter. Several correction algorithms are examined using numerical simulations. BPM requirements and orbit feedback concept will be discussed, with reference to some available data on dynamic disturbances such as ground motion at the PSI site, e.g. at the SwissFEL injector test facility currently under commissioning.