• G.M. Kazakevich
  Fermilab, Batavia, Illinois
• Y.U. Jeong, B.C. Lee, S.-H. Park
  KAERI, Daejon
• G.I. Kuznetsov
  BINP SB RAS, Novosibirsk
• V. M. Pavlov
  Strathclyde University, Glasgow

Funding: Budker Institute of Nuclear Physics RAS, Academician Lavrentyev 11, Novosibirsk, 630090, Russia; Laboratory for Quantum Optics, Korea Atomic Energy Research Institute, P. O. Box 105, Yusong, Taejon, 305-600, South Korea.

A reliable injection system of the widely tunable microtron-based terahertz Free Electron Laser (FEL) has been developed and during last few years provides stable operation of the FEL for users. The system is based on the long-life thermionic cathode assembly using 2.5 mm-in diameter monocrystalline LaB6 emitter, heated by the tungsten cylindrical filament with the power consumption less than 50 W. The cathode emits the macro-pulse current in the range of 1-1.4 A providing operation of the terahertz FEL during more than 1000 h. The cathode assembly is installed on the cover of the I-type microtron accelerating cavity in location providing an efficient injection for the acceleration with variable number of orbits. This variation widely changes the energy of the electron beam and allows on-the-fly retuning of the FEL in the range of 1-3 THz. Pulse-signal system stabilizing the emission current prevents randomized break-downs in the accelerating cavity and decreases macro-pulse power fluctuations of the FEL radiation. The fluctuations were measured to be less than 10% during long-time operation.

• J.-Y. Raguin, R.J. Bakker, K.S.B. Li, M. Pedrozzi
  PSI, Villigen

In the Low Emittance Gun (LEG) under development at PSI an extremely bright electron beam is produced from a field emission array and then rapidly accelerated in a diode configuration up to 1 MeV with gradients of the order of 250 to 500 MV/m. The electronic emission from such a cold cathode allows normalized intrinsic emittance below 0.1 mm.mrad well suited for X-ray FELs or linear collider applications. The diode is followed by an L-band RF-gun like cavity to further accelerate the beam. A third harmonic field is superposed to the fundamental [1] 1.5 GHz pi-mode field to minimize the RF emittance. We report here on the design of such a two-frequency RF cavity with some details on the RF coupling and possible tuning mechanisms. Beam dynamics studies, performed with PARMELA and the fully self-consistent code MAFIA, are presented and compared with the results obtained for an RF cavity excited with the fundamental frequency only.

[1] D.H. Dowell et al., Nucl. Instr. and Meth. A 528 (2004) 316.

• 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.

• R. Kuroda
  AIST, Tsukuba, Ibaraki
• H. Hayano, J.U. Urakawa
  KEK, Ibaraki
• K. Hidume, M. Kawaguchi, S. Minamiguchi, R. Moriyama, T. Saito, K. Sakaue, M. Washio
  RISE, Tokyo
• S. Kashiwagi
  ISIR, Osaka

Funding: This research was partially supported by a High Tech Research Project of MECSST 707, a Grant-in-Aid for Scientific Research (B) 16340079, a Grant-in-Aid for Young Scientists (B) 16760049.

A compact soft X-ray source is required in various research fields such as material and biological science. The laser undulator based on Compton backward scattering has been developed as a compact soft X-ray source for the biological observation at Waseda University. It is performed in a water window region (250eV - 500 eV) using the interaction between 1047 nm Nd:YLF laser (10ps FWHM) and about 5 MeV high quality electron beam (10ps FWHM) generated from rf gun system. The range of X-ray energy in the water window region has K-shell absorption edges of Oxygen, Carbon and Nitrogen, which mainly constitute of living body. Since the absorption coefficient of water is much smaller than the protein's coefficient in this range, a dehydration of the specimens is not necessary. To generate the soft X-ray pulse stably, the electron beam diagnostics have been developed such as the emittance measurement using double slit scan technique, the bunch length measurement using two frequency analysis technique. In this conference, we will report results of beam beamdiagnostics experiments, soft X-ray generation and our future plan.