Submillimeter generation in intercavity scattering scheme with two sheet relativistic electron beams

In experiments at ELMI-device (BINP, Novosibirsk) the operation of 4-mm free electron maser (FEM) with two dimensional distributed feedback was demonstrated [1, 2]. These results gave a base for development multichannel planar FEM with 2-D distributed feedback [3]. In case of two channels jointed by special waveguide 2-D distributed feedback can be also used for two stage generation of submillimeter radiation exploiting an intercavity scattering scheme [3]. As the first step on studying of two stage generation we performed the experiments on simultaneous generation and transport of two intensive sheet electron beams. We modified the geometry of a ribbon accelerator diode at the ELMI-device and realized simultaneous generation of two sheet beams with the following parameters: the electron energy − 0.8 MeV, the total current of each beam - 3 kA, the cross section 0.4×7 cm and the pulse duration - 3 mcs. These sheet beams were transported on the length 1.3 m in slit vacuum channels with cross section 0.95×9 cm in the guiding magnetic field 1.7 T [4]. Next step of this series of experiments is devoted to realization of the two stage scheme. The paper presents results of the experiments and theoretical analysis of a prospect of the two stage scheme for THz pulses generation.