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Mode splitting effect in FEMs with oversized Bragg resonators

Journal Article · · Physics of Plasmas
DOI:https://doi.org/10.1063/1.4956445· OSTI ID:22600050
;  [1]; ; ;  [2];  [1]
  1. Institute of Applied Physics Russian Academy of Sciences, Nizhny Novgorod (Russian Federation)
  2. Joint Institute for Nuclear Research, Dubna (Russian Federation)
Splitting of the fundamental mode in an oversized Bragg resonator with a step of the corrugation phase, which operates over the feedback loop involving the waveguide waves of different transverse structures, was found to be the result of mutual influence of the neighboring zones of the Bragg scattering. Theoretical description of this effect was developed within the framework of the advanced (four-wave) coupled-wave approach. It is shown that mode splitting reduces the selective properties, restricts the output power, and decreases the stability of the narrow-band operating regime in the free-electron maser (FEM) oscillators based on such resonators. The results of the theoretical analysis were confirmed by 3D simulations and “cold” microwave tests. Experimental data on Bragg resonators with different parameters in a 30-GHz FEM are presented. The possibility of reducing the mode splitting by profiling the corrugation parameters is shown. The use of the mode splitting effect for the output power enhancement by passive compression of the double-frequency pulse generated in the FEM with such a resonator is discussed.
OSTI ID:
22600050
Journal Information:
Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 7 Vol. 23; ISSN PHPAEN; ISSN 1070-664X
Country of Publication:
United States
Language:
English