Dispersion characteristics of plasma-filled cylindrical waveguide

An analytical and numerical study is made onthe dispersion properties of a cylindrical waveguide filledwith plasma. An electron beam and static external magneticfield are considered as the mechanisms for controllingthe field attenuation and possible stability of the waveguide.The effects of plasma warmness and inhomogeneityare also considered. Dispersion relations in x describingdifferent physical situations that govern the mode propagationin the waveguide are obtained. The plasma dielectrictensors and the dispersion relations which describe E and Hwaves and, hence, the damping rate of these waves arecalculated and studied. The necessary conditions for thefield stability in the waveguide and amplification coefficientsfor these waves are also obtained. H-wave modes arealways attenuated by collisional effect. The growth of theexcited E wave is calculated in the resonance case, andthe stability condition for the E wave is obtained. E wavesare found to be more stable in warm plasma compared tocold plasma. The results obtained here are of great interestand may be used to analyze how the plasma affects theelectromagnetic properties of the cavity of the 1–2 MW140–170 GHz continuous-wave gyrotron (for W7-X stellaratorand ITER), for MW gyrotron development for fusionplasma applications, and for second harmonic generation ina plasma-filled parallel plane waveguide.