Progress in free-electron maser experiment at CESTA

摘要

At C.E.S.T.A., the 35 GHz FEM ONDINE I experiment is in progress. The work done this year focused on beam creation and propagation on the Euphrosyne generator with both an oxide cathode and a cold cathode: typically, 1 kA at 2.5 MeV is propagated. A lot of calculations have been done on these problems and we have also developed simulation codes on FEM interaction in both Compton and Raman regimes, taking into account 3D wiggler field, guiding field, waveguide modes, electron beam injection to obtain trajectories, gain and efficiency. Good agreement with some previous experiments and codes has been found. A microwave apparatus has already been completed to work in an amplifier configuration: injection magnetron line (100 kW), amplification line and diagnostics (wavenumber analysis for full mode analysis, filters, detectors, etc.). All these components are compatible with the future high repetition rate ONDINE II experiment using the LELIA induction linac. The FEM experiment is now starting at 0.1 Hz with the 1.5 MeV LELIA injector. Beam creation from a thermionic cathode and propagation have been fully studied theoretically and experimentally. An electron beam of 1.3 kA at 1.3 MeV with an emittance of around 200 $pi@-mm-mrad is likely to be compatible with an efficient FEM operation.