Generation of powerful ultrashort electromagnetic pulses based on superradiance

(TU-3-09)

N. Ginzburg, I. Zotova, A. Sergeev, R. Rosenthal, A. Phelps*, A. Cross*, S. Wiggins*, K. Ronald*, V. Shpak**, M. Yalandin, S. Shunailov**, M. Ulmaskulov**  

Institute of Applied Physics, RAS, Nizhny Novgorod, Russia; *University of Strathclyde, Glasgow, UK; **Institute of Electrophysics, RAS, Ekaterinburg, Russia

The review of experimental and theoretical results on the observation of superradiance from a single subnanosecond intense electron bunch will be presented. Generation of superradiance pulses was associated with different varieties of stimulated emission (cyclotron, wiggler, Cherenkov).

The pulses with the maximum peak power were generated based on the Cherenkov mechanism, when electron bunches moved through a periodic-waveguide and interacted with a backward propagating wave. The processes of microwave pulse generation were associated with self-bunching and the mutual influence of different parts of the electron pulse due to slippage of the wave with respect to the electrons and thus can be interpreted as superradiance. The peak power was proportional to the square of the total bunch charge. Observation of RF breakdown of ambient air, as well as direct measurements by hot-carrier germanium detectors, leads to an estimate of the absolute peak power as high as 150 MW for the 300 ps pulses at 38 GHz. These results corresponded with the results of numerical simulations using the PIC code KARAT. The observation of 75 GHz and 150 GHz microwave pulses with duration less than 150 ps and radiation power 10-15 MW and 5-10 MW respectively are also reported.