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2 pp. (2005)., The maximum, measured energy-contribution of ACC5 at TTF2 is 26.5 + 0.7 MV/m over 7 cavities, each 1.035 m long. For ACC5 gradient measurements, a comparison was made between the beam energy with ACC4 and 5 off and the beam energy with ACC4 detuned and ACC5 cavities 1-7 tuned. The maximum gradient was determined by increasing the amplitude of the RF until the cavity quenched. ACC5 cavities 1-7 were tuned to maximum gradient such that the RF pulse-shape had a flat top. The phase of the RF was, however, 30 + 10 degrees different from the beam phase for 6 of 7 cavities, producing 12.1 + 1.5 % less beam energy than on-crest operation would’ve produced. The beam energy was determined with a beam image on a screen in the dispersive region of the bypass-dogleg and the strength of the upstream dipole.

4 pp. (2002)., In this paper we describe the regeneration of electron bunches from the RF gun by back-reflected radiation from VUV SASE FEL at the TESLA Test Facility (TTF) at DESY. The SASE FEL was running at the wavelength 96 nm with 30– 100 fs pulses, SASE pulse energy was up to 20 μJ . “Nominal” electron bunches for lasing were produced by RF gun with Cs 2 Te photocathode driven by UV quantum laser system. “Parasitic” bunches with a charge up to 1– 1.5 nC were extracted from the RF gun due to VUV FEL radiation reflected from the mirror (placed downstream of the undulator) to the cathode. Nontrivial dependence of a charge on a SASE pulse energy was found.