Euphrosyne a pulsed electron generator for FEL application

At CESTA, the 35 GHz experiment ONDINE I is in progress. The studies focus on intense electron beam creation with the Euphrosyne generator and its propagation to the wiggler by means of a transmission line. The generator consists of a Marx generator, a pulse forming line and a diode using both thermionic and cold cathodes. The diode has been adapted to the forming line at 36 ohms in order to narrow the energetic spectrum. A full characterization of the beam has been achieved by measuring the position, the size with Cerenkov detectors, the energetic spectrum and the transverse emittance at different points of the transmission line. Calculations have been done by using envelope and particle codes to perform the propagation of the beam. Good agreement has been achieved. Typically, 1 kA at 1.5 MeV is obtained. In the frame of a preliminary superradiant experiment using a bifilar helical wiggler, the authors have measured an amplification of the spontaneous emission up to 1 MW in the Ka band and .2 MW in the 33-36 GHz band