• R. Tatchyn
  SLAC, Menlo Park, California

The unusually long insertion devices being prepared for Angstrom-wavelength Free Electron Lassers (FELs) will generate spectral-angular distributions in the proposed experimental areas substantially different from those conventionally calculated for the far field. In this paper we report on computational simulations of near vs. far field distributions for the SLAC linac Coherent Light Source (LCLS) undulator, an insertion device approximateely 140 meters long. The properties of the coherent radiation as a limiting case of the near-field emission, for the special condition of a microbunched beam radiating along the undulator axis, are reviewed.

• R. Tatchyn
  SLAC, Menlo Park, California

The temporal resolution of pump-flash interactions in the ultrashort (fs-as) regime is limited by the characteristic time constants of the excited states in the detector material. If the relaxation time constant is appreciably longer that the time interval between the pump and probe signals the response of the detector material to the probe represents a temporal convolution of the pump and probe responses, setting a lower limit on the resolution to which the interval between the two pulses can be measured. In most of the solid state ultrafast detection schemes that are being considered for the ultra-short pulse x-ray sources under current development at SLAC and elsewhere the characteristic time constants are related to the bound states of the atoms comprising the material or to the relaxation times of phase transitions or charge carrier populations of the lattice, setting a probable lower limit on the attainable resolution on the order of ~0.1 ps. In this paper we consider a novel detection principle predicated on the excitation of specially prepared unbound states in an ionized plasma and estimate its potential for extending the lower limit of resolution into the as regime.

• A.A. Shcherbakov, V.P. Androsov, E.V. Bulyak, A. Dovbnya, I.V. Drebot, P. Gladkikh, V.A. Grevtsev, Yu.N. Grigor'ev, A. Gvozd, V.A. Ivashchenko, I.M. Karnaukhov, V.P. Kozin, V. Lapshin, V.P. Lyashchenko, V. Markov, N.I. Mocheshnikov, V.B. Molodkin, A. Mytsykov, I.M. Necklyudov, F.A. Peev, A.V. Rezaev, A. Shpak, V.L. Skirda, V. Skomorokhov, Y.N. Telegin, V.I. Trotsenko, A.Y. Zelinsky, O.D. Zvonarjova, N. kovalyova
  NSC/KIPT, Kharkov
• A. Agafonov, A.N. Lebedev
  LPI, Moscow
• J.I.M. Botman
  TUE, Eindhoven
• R. Tatchyn
  SLAC, Menlo Park, California

The sources of the X-rays based on Compton scattering of intense Nd:YAG laser beam on electron beam circulating in a storage ring with beam energy 43 - 225 MeV is under construction in NSC KIPT. In the paper the progress in development and construction of Kharkov X-ray generator NESTOR is presented. The current status of the main facility system design and development are described. New scheme and main parameters of injection system are presented. The facility is going to be in operation in the middle of 2007 and generated X-rays flux is expected to be of about 10(13) phot/s.