Chirping of Gyrotron Radiation in the Process of Raman Backscattering on Electron Beam with Variable Voltage for Subsequent Pulse Compression

We demonstrate theoretically the possibility of using the regime of Raman backscattering of forward pump wave into the backward propagating signal wave for tuning the radiation frequency. Absolute instability that develops in this system, makes it possible to smoothly change the frequency of the scattered signal when the electron energy changes. According to simulations, with use of 50 kW, 35 GHz gyrotron as a pump wave source considered modulator can generate frequency tunable signal in 3GHz bandwidth with up to 60% conversion efficiency. For subsequent compression of chirped pulse, we suggest to use multi-fold helically corrugated waveguides which allowed us to obtain pulses with peak power up to the 2 MW.