Multichannel planar FEM as a base for archiving large energy content in pulses of coherent mm-radiation

Summary form only given. The concept to achieve an extremely large energy content in millimeter radiation pulse, which is based on a scheme of a planar maser driven by a high-current sheet electron beam, is discussed in the paper. This concept is founded on that a submegajoule energy level is achieved in the experiment for high brightness microsecond sheet beams, and a high degree of spatial coherence in the radiation generated by the planar maser can be obtained by applying 2-dimensional distributed positive feedback (2DPF). Theoretical analysis and experiments at the ELMI-device have proved that two dimensional Bragg gratings are suitable to realize 2DPF in such planar maser. However, the experiments also have shown, that microwave discharge in electrodynamic structure limits pulse duration and energy content. Using one-dimensional Bragg gratings to compose downstream reflector should decrease the energy density in the resonator. The results of experiments with such combined resonator are also presented in the paper. In order to develop the pointed concept we have considered an opportunity to operate this planar maser as an amplifier. In order to increase a small size of the ribbon electromagnetic flow we have also suggested to adjoin close each to other a large number of identical planar masers united in a single device due to formation of a common distributed positive feedback by means of 2-dimensional Bragg structures. In a final part of the paper the project on experimental verification of opportunity to achieve the synchronism between channels in multichannel planar maser at the ELMI-device is presented.