Amplification and self-compression of ultrashort electromagnetic pulse propagating along quasi-stationary electron beam

Summary for only given. The first experiments on observation of amplification of ultrashort microwave superradiance (SR) pulses under propagating along quasistationary electron beams were performed. For this purpose the experimental set-up based on two synchronized high current accelerators RADAN was build up. The first accelerator was used to drive the 37 GHz generator of SR pulses with duration -300 ps based on relativistic BWO. The second accelerator with current up to 1.2 kA and electron energy -300 keV drives the amplification section formed by dielectric loaded waveguide. In accordance with theoretical analysis amplification of SR pulse (minimum in 4 times on power) was accompanied by significant shortening of its duration less than 100 ps [1]. At the next stage we plane after modification to use this experimental set up for observation of effect of self-induced transparency and nonlinear compression. Based on analogy to well known process of the self-induced transparency of an optical pulse propagating through a passive two-level medium we described similar effects for a microwave pulse interacting with a cold plasma or rectilinear electron beam under cyclotron resonance condition [2]. It is shown that with increasing amplitude and duration of an incident pulse the linear cyclotron absorption is replaced by the self-induced transparency when the pulse propagates without damping. In fact, the initial pulse decomposes to one or several solitons with amplitude and duration defined by its velocity. In a certain parameter range, the single soliton formation is accompanied by significant compression of the initial electromagnetic pulse. We suggest to use the effect of self compression for producing sub-gigawatt and multi-gigawatt picosecond microwave pulses. In the case of interaction with backward propagating wave of interest the effect of formation of standing soliton with zero group velocity.