• J. Bödewadt, J. Roßbach
  Uni HH, Hamburg
• R. Ischebeck
  PSI, Villigen
• B. Polzin, H. Schlarb, A. Wagner
  DESY, Hamburg

A seeded free-electron laser operating in the soft X-ray (XUV) spectral range will be added to the SASE FEL facility FLASH. The seed beam will be generated by higher harmonics of a near infrared laser system. A dedicated transport system will guide the radiation into the electron accelerator environment. Within the seed undulator section compact diagnostic units have to be designed to control the transverse overlap of the photon and the electron beam. These units contain a BPM a wire scanner and an OTR screen for the electron diagnostic. A Ce:YAG screen and a MCP readout for the wire scanner are foreseen to measure the photon beam position.

• V. R. Arsov, M.K. Bock, M. Felber, P. Gessler, K.E. Hacker, F. Löhl, F. Ludwig, K.-H. Matthiesen, H. Schlarb, A. Winter
  DESY, Hamburg
• S. Schulz, L.-G. Wißmann, J. Zemella
  Uni HH, Hamburg

The need for timing and bunch-length monitors for free-electron lasers and other accelerators makes the electro-optic spectral decoding (EOSD) a promising diagnostic technique. Being non-destructive, it allows a single shot-measurement within the accelerator environment. In some cases, e.g. low charge or necessity to resolve time-structures below 20 fs, the bunch length is measured indirectly, using the spectrum of the coherent transition radiation (CTR). We present results of EOSD measurements on the CTR beam line at FLASH, using a chirped Ti:Sapphire oscillator pulse focused simultaneously with the THz radiation on a GaP crystal in vacuum. The CTR spectrum is in the range 200 GHz-100 THz and and the pulse energy in the focus is over 10 mJ. The measured narrow CTR temporal profiles in the order of 400 fs FWHM demonstrate, that the ultra short THz-pulses, emitted by the compressed electron bunches are transported through the 19 m long beam line without significant temporal broadening.

• V.G. Ziemann, G. Angelova Hamberg
  Uppsala University, Uppsala
• J. Bödewadt
  Uni HH, Hamburg
• S. Khan
  DELTA, Dortmund
• M. Larsson, P.M. Salén, P. van der Meulen
  FYSIKUM, AlbaNova, Stockholm University, Stockholm
• F. Löhl, E. Saldin, H. Schlarb, E. Schneidmiller, A. Winter, M.V. Yurkov
  DESY, Hamburg
• A. Meseck
  Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin

We present very promising recent results from the optical replica synthesizer experiment in FLASH where we manipulate ultrashort electron bunches in FLASH with a laser in order to stimulate them to emit a coherent light pulse with the temporal structure of the electron bunches and subsequently analyze the light pulses with laser diagnostic (FROG) methods.

Slides