This article is cited in 1 paper

OPTICS AND NUCLEAR PHYSICS

Generation spectrum of long-pulse free-electron terahertz lasers: quasilinear theory

N. S. Ginzburg^ab, E. R. Kocharovskaya^ba, A. S. Sergeev^b, S. E. Fil'chenkov<sup>b

a</sup> Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, 603022 Russia
^b Federal Research Center Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, 603950 Russia

Abstract: A quasilinear theory is developed for free-electron lasers in which intense electron beams with a significant velocity dispersion are used to implement the kinetic regime of electron–wave interaction. Under the assumption that the field is stored in a high-$Q$ cavity, stationary distributions of the spectral density of excited cavity modes are found for various levels of the excess of the beam current above the threshold. It is shown that, if the excess is large, the energy distribution of the electrons that exit the cavity includes a plateau with the width proportional to the generation spectrum width. Parameters are estimated for long pulse free-electron lasers that can be implemented on the basis of linear induction accelerators. It is shown that the energy of high-dispersion electron beams can be efficiently converted into broadband terahertz radiation.

Received: 13.04.2021
Revised: 13.04.2021
Accepted: 15.04.2021

DOI: 10.31857/S1234567821100049

 English version: Journal of Experimental and Theoretical Physics Letters, 2021, 113:10, 626–630

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