Simple macroscopic theory of cyclotron maser instabilities
Abstract
The stability of an annular layer of relativistic electrons, guided by a uniform magnetic field inside a circular waveguide is analyzed using a fluid dynamical treatment. The simple theory presented here is aimed at providing some perspective of the cyclotron maser instability which traditionally has required an analysis in phase space. The same dispersion relationship is recovered from the macroscopic fluid model. Thus in addition to the usual interpretation in terms of phase bunching in the electronic motions, the cyclotron maser instability may also be regarded simply as a growing spacecharge wave in a relativistic beam which is in synchronism with the surrounding structure, or as due to current bunching, or even as an instability of the shear flow of a rotating relativistic electron fluid. Such a variety of interpretations emerges because the cyclotron maser instability is recently identified as the negative mass instability in rotating relativistic beams. The ac spacecharge effects are completely accounted for in the present study.
 Publication:

IEEE Transactions on Electron Devices
 Pub Date:
 February 1982
 DOI:
 10.1109/TED.1982.20703
 Bibcode:
 1982ITED...29..320L
 Keywords:

 Cyclotron Radiation;
 Macroscopic Equations;
 Magnetic Fields;
 Magnetohydrodynamic Stability;
 Maser Outputs;
 Relativistic Electron Beams;
 Electron Bunching;
 Flow Stability;
 Larmor Radius;
 Rotating Fluids;
 Shear Flow;
 Space Charge;
 Wave Dispersion;
 Waveguides;
 Lasers and Masers