An electron beam can be made to interact with an undulator magnet so that a collective unstable mode is excited. In this mode, the beam generates coherent radiation whose wavelength is determined by the undulator period and the electron energy. By proper choice of the electron-beam energy, energy dispersion, and density, one can obtain coherent radiation in the soft-x-ray region with peak and a...

The most important characteristics of an X-ray SASE-FEL are determined by the electron beam energy, transverse and longitudinal emittance, and by choice of the undulator period, field, and gap. Among them are the gain and saturation length, the amount and spectral characteristics of the spontaneous radiation, the wake fields due to the vacuum pipe. The spontaneous radiation intensity is very la...

1 Neptune Laboratory, Departments of Electrical Engineering and Physics, University of California, Los Angeles, CA 90095, U.S.A. 2 STI Optronics, Inc., Bellevue, WA 98004-1495, USA Abstract. IFEL and FEL techniques can be used to modulate an electron beam on the scale of the radiation wavelength. However, the lack of a high power radiation source in the 100-300 μm range hinders the progress on ...

We propose a new method for measurements of the longitudinal profile of 100 femtosecond electron bunches for X-ray Free Electron Lasers (XFELs). The method is based on detection of coherent undulator radiation produced by modulated electron beam. Seed optical quantum laser is used to produce exact optical replica of ultrashort electron bunches. The replica is generated in apparatus which consis...

A comprehensive analysis is presented that describes amplification of a seed THz pulse in a single-pass free-electron laser (FEL) driven by a photoinjector. The dynamics of the radiation pulse and the modulated electron beam are modeled using the time-dependent FEL code, GENESIS 1.3. A 10-ps (FWHM) electron beam with a peak current of 50–100 A allows amplification of a 1 kW seed pulse in the fr...

We investigate, both analytically and numerically, the influence of the dechanneling process on the parameters of undulator radiation generated by ultrarelativistic positron channelling along a crystal plane, which is periodically bent. The bending might be due either to the propagation of a transverse acoustic wave through the crystal, or due to the static strain as it occurs in superlattices....

The analytical and numerical calculations for the dynamic of single electron and beam in RF undulator have been conducted and compared. The transverse and longitudinal velocity, trajectory, energy variation, and the spontaneous radiation are studied. It is found that the forward and backward wave (FW/BW) components have different contribution on electron motion and radiation, most of the energy...

The radiation of relativistic charged particles for the quasiperiodic motion in a transparent medium is considered. For motion of the general kind the differential probability of the process is obtained. For planar motion the spectral intensity of radiation is found. The different cases of radiation in the medium-filled undulators are studied. In particular, the influence of Cherenkov radiation...