Influence of wall impedance on the electron cyclotron maser instability
Abstract
The influence of finitewall impedance on the cyclotron maser instability is investigated for a hollow electron beam. The stability analysis is carried out within the framework of the linearized VlasovMaxwell equations, assuming that the beam thickness is much less than the mean radius of the beam. The formal dispersion relation for azimuthally symmetric electromagnetic perturbations including the important influence of arbitrary wall impedance is obtained. One of the most important features of the analysis is that, for a purely resistive wall, the instability growth rate is substantially reduced by a very small wall resistivity. Moreover, the range of axial wavenumbers corresponding to instability increases rapidly as the wall resistivity is increased. Cyclotron maser stability properties for a dielectric loaded waveguide are also investigated. For an appropriate choice of the dielectric constant ɛ and the thickness of the dielectric material, it is shown that the instability bandwidth can be more than double that for a perfectly conducting waveguide.
 Publication:

Physics of Fluids
 Pub Date:
 December 1980
 DOI:
 10.1063/1.862955
 Bibcode:
 1980PhFl...23.2538U
 Keywords:

 Cyclotron Radiation;
 Electrical Impedance;
 Electron Beams;
 Electron Radiation;
 Maser Outputs;
 Surface Reactions;
 Dielectrics;
 Laser Stability;
 Maxwell Equation;
 Microwave Emission;
 Vlasov Equations;
 Walls;
 Wave Dispersion;
 Waveguides;
 Lasers and Masers