• A. Falone, H. Fitze, R. Ischebeck, Y. Kim, M. Pedrozzi, V. Schlott, B. Steffen, L. Stingelin
  PSI, Villigen
• D. Alesini, L. Ficcadenti, L. Palumbo
  INFN/LNF, Frascati (Roma)

RF deflectors are crucial diagnostic tools for bunch length and slice emittance measurements with sub-picosecond resolution. Their use is essential in commissioning and operation of VUV and X-ray FELs. The 250MeV FEL injector, under construction at PSI, will use two of them. The first one will be installed after the gun at low energy (~7MeV), the second one at the end of the Linac at high energy (250MeV). The first RF deflector consists of a single cell standing wave cavity working on the TM110 deflecting mode, and tuned at 2997.912 MHz (frequency of the linac structures). In this note we report the motivation of this measurement, beam dynamics and beam diagnostics considerations and the RF design and simulations of this cavity.

• A. Streun, M. Böge, N. Milas, F. Müller, V. Schlott, H. Sigg
  PSI, Villigen
• G.A. Amatuni, D. Gishyan, K. Manukyan, A. Sargsyan
  CANDLE, Yerevan

Recently tentative top-up operation of the Swiss Light Source (SLS) storage ring at low momentum compaction factor has been started. We will present an analysis of the longitudinal dynamics and simulations of the injection process, and explain our method to ensure closed orbit stability. First experimental results will be shown and compared to the model predictions.