Generation of powerful subnanosecond microwave pulses by intense electron bunches moving in a periodic backward wave structure in the superradiative regime

Ginzburg, N S and Novozhilova, N Y and Zotova, I V and Sergeev, A S and Peskov, N Y and Phelps, A D R and Wiggins, S M and Cross, A W and Ronald, K and He, W and Shpak, V G and Yalandin, M I and Shunailov, S A and Ulmaskulov, M R and Tarakanov, V P (1999) Generation of powerful subnanosecond microwave pulses by intense electron bunches moving in a periodic backward wave structure in the superradiative regime. Physical Review E: Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, 60 (3). pp. 3297-3304. ISSN 2470-0053 (https://doi.org/10.1103/PhysRevE.60.3297)

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Abstract

Experimental results of the observation of coherent stimulated radiation from subnanosecond electron bunches moving through a periodic waveguide and interacting with a backward propagating wave are presented. The subnanosecond microwave pulses in Ka and W bands were generated with repetition frequencies of up to 25 Hz. The mechanism of microwave pulse generation was 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; this can be interpreted as superradiance. The illumination of a panel of neon bulbs resulted in a finely structured pattern corresponding to the excitation of the TM01 mode. 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 60 MW for the 390-ps pulses at 38 GHz. These results are compared with numerical simulations. The initial observation of 75-GHz, 10-15-MW radiation pulses with a duration of less than 150 ps is also reported. [S1063-651X(99)00709-6].