On Theory of Superheterodyne FELs with Longitudinal Electrostatic Undulator

Authors A.V. Lysenko1 , A.Yu. Brusnik1, I.I. Volk1 , M.A. Korovai1, S.S. Ilin1, O.L. Bunetskyi2

1Sumy State University, 2, Rimsky-Korsakov Str., 40007 Sumy, Ukraine

2O.Ya. Usikov Institute for Radiophysics and Electronics of the National Academy of Sciences of Ukraine, 12, Ac. Proskura Str., 61085 Kharkiv, Ukraine

Е-mail lysenko_@ukr.net
Issue Volume 12, Year 2020, Number 4
Dates Received 29 March 2020; revised manuscript received 20 August 2020; published online 25 August 2020
Citation A.V. Lysenko, A.Yu. Brusnik, I.I. Volk, et al., J. Nano- Electron. Phys. 12 No 4, 04037 (2020)
DOI https://doi.org/10.21272/jnep.12(4).04037
PACS Number(s) 41.60.Cr, 52.59.Ye
Keywords Superheterodyne Free-electron laser, Electrostatic undulator, Parametric resonance, Space charge waves, Wave growth rates.

Within the framework of the quadratic nonlinear approximation, the amplification characteristics of a single-stream superheterodyne free electron laser were analysed. Such device used two mechanisms of the electromagnetic signal amplification: the mechanism of parametric amplification of the electromagnetic wave using a traditional undulator with transverse periodically reversing magnetic field, and an additional amplification mechanism using longitudinal electrostatic undulator. By means of the averaged characteristics method, we obtained a system of differential equations describing the dynamics of the wave harmonics in superheterodyne free electron laser. Plural three-wave parametric resonant interactions between harmonics of different space charge wave types were discovered in the system. To implement such plural interactions, it was sufficient to have a monochromatic electrostatic pump field. We achieved and analysed an expression for the growth rate related to both the parametric instability of transverse waves and the parametric instability of longitudinal waves in an electrostatic undulator. We showed that the additional gain provided by the electrostatic undulator found its most efficient use in the systems characterized by relatively small values of the beam relativistic factor and rather high values of the electromagnetic signal frequency. We demonstrated the prospect of using such superheterodyne free electron lasers with longitudinal electrostatic undulator as a powerful amplifier in the millimeter-submillimeter wavelength range.

List of References