title: Generation of powerful subnanosecond microwave pulses by intense electron bunches moving in a periodic backward wave structure in the superradiative regime.
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 300-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.
authors.affiliation: Institute of Applied Physics, RAS, 603600 Nizhny Novgorod, Russia.
authors.forename: N S
authors.initials: NS
authors.lastname: Ginzburg
authors.forename: N Y
authors.initials: NY
authors.lastname: Novozhilova
authors.forename: I V
authors.initials: IV
authors.lastname: Zotova
authors.forename: A S
authors.initials: AS
authors.lastname: Sergeev
authors.forename: N Y
authors.initials: NY
authors.lastname: Peskov
authors.forename: A D
authors.initials: AD
authors.lastname: Phelps
authors.forename: S M
authors.initials: SM
authors.lastname: Wiggins
authors.forename: A W
authors.initials: AW
authors.lastname: Cross
authors.forename: K
authors.initials: K
authors.lastname: Ronald
authors.forename: W
authors.initials: W
authors.lastname: He
authors.forename: V G
authors.initials: VG
authors.lastname: Shpak
authors.forename: M I
authors.initials: MI
authors.lastname: Yalandin
authors.forename: S A
authors.initials: SA
authors.lastname: Shunailov
authors.forename: M R
authors.initials: MR
authors.lastname: Ulmaskulov
authors.forename: V P
authors.initials: VP
authors.lastname: Tarakanov