Seminars Archive

Overview and commissiong results of the seeding experiment at FLASH

Abstract
During the last shutdown the Free-electron LASer in Hamburg (FLASH) has been upgraded with several new installations. A new third-harmonic module allows to control the bunch compression and to generate relatively long electron bunches (few hundred fs) with high peak current. The relaxed timing requirements (with respect to the “spike mode‿) provide the opportunity to test a direct seeding configuration in the XUV spectral range: this is the so-called sFLASH experiment. A 40 fs long Ti:Sa laser is focused into a noble gas jet and produces high harmonics. The seed pulses are injected in a 10 m long variable gap undulator tuned at the resonant wavelength. Since the amplification process does not start from the shot-noise (as in the SASE process) but from a coherent laser pulse, the resulting radiation should preserve this feature and the temporal jitter should be eliminated. After the extraction of the radiation in a magnetic chicane, a short branch in the tunnel accommodates the photon diagnostics for the characterization of the seeded FEL radiation. In this talk the experimental setup will be presented and the first results from the commissioning started this summer will be discussed. (Rif. Enrico Allaria)