High-Power Free-Electron Masers Based on Linear Induction Accelerators

We review the results of theoretical and experimental studies of high-power free-electron masers (FEMs), which are performed jointly by the Joint Institute for Nuclear Research (JINR) and the Institute of Applied Physics of the Russian Academy of Sciences (IAPRAS), using the LIU-3000 linear inductio...
Ausführliche Beschreibung

We review the results of theoretical and experimental studies of high-power free-electron masers (FEMs), which are performed jointly by the Joint Institute for Nuclear Research (JINR) and the Institute of Applied Physics of the Russian Academy of Sciences (IAPRAS), using the LIU-3000 linear induction accelerator that has a particle energy of about 0.8 MeV, a beam current of up to 200 A, and a pulse duration of 200–250 ns. Various types of Bragg resonators are compared, including two-mirror schemes and resonator cavities with a jump in the corrugation phase. The nonlinear dynamics of FEMs with the cavities of the above-specified types is studied, and the regions of realization of single-mode, single-frequency regimes, when generators are excited by relativistic electron beams moving in a helical undulator and focused by a uniform longitudinal magnetic field, are found. The results of the theoretical analysis are confirmed by experimental studies. When a Bragg cavity with a corrugation phase jump is used in the regime of the reverse guiding field in the 8-mm wavelength range, a FEM with an output power of about 20–30 MW and a radiation spectrum width of 6–7 MHz is realized, which is close to the theoretical limit. The record-breaking set of parameters obtained for this class of generators (efficiency, power, stability of the single-mode generation regime in a sequence of up to $ 10^{6} $ pulses) made it possible to use FEM radiation in several applications, including the study of the resource of high-gradient accelerating structures under pulsed periodic thermal loads. To expand the spectrum of potential applications that require control over the frequency and phase of the radiation, the possibility to create wideband amplifying circuits of FEMs is demonstrated. In order to bring FEMs over to the short-wave part of the millimeter-wavelength range, it is proposed to use modified Bragg structures based on the coupling of traveling and quasi-critical waves. It is shown that including quasi-critical waves in the feedback circuit allows one to improve significantly the selectivity of Bragg cavities (as compared with their “conventional” analogs based on the coupling of counterpropagating wave beams with high group velocities) for the transverse dimensions that reach up to 10–20 wavelengths. Operability of novel cavities has been confirmed experimentally in prototypes of FEM oscillators operating in the $ K_{a} $- to W-bands at a multimegawatt power level and having a transverse dimension of up to 5 wavelengths. Prospects for advancing the studied class of generators to the subterahertz/terahertz frequency range on the basis of new-generation linear induction accelerators, which have been developed at the Budker Institute of Nuclear Physics (BINP), Siberian Branch of the Russian Academy of Sciences and form electron beams with a particle energy of 5–20 MeV and kiloampere currents, are discussed. Ausführliche Beschreibung

Autor*in:	Peskov, N. Yu. [verfasserIn] Ginzburg, N. S. Kaminsky, A. K. Sedykh, S. N. Sergeev, A. S.

Format:	E-Artikel
Sprache:	Englisch

Erschienen:	2021

Anmerkung:	© Springer Science+Business Media, LLC, part of Springer Nature 2021

Übergeordnetes Werk:	Enthalten in: Radiophysics and quantum electronics - New York, NY [u.a.] : Consultants Bureau, 1965, 63(2021), 12 vom: Mai, Seite 931-975
Übergeordnetes Werk:	volume:63 ; year:2021 ; number:12 ; month:05 ; pages:931-975

Links:	Volltext

DOI / URN:	10.1007/s11141-021-10105-8

Katalog-ID:	SPR04546619X