Analysis of the Negative Absorption of Plasma-Cavity System

Abstract

A possibility of amplification by a cylindrical cavity of reflection type coaxial with a plasma column along the static magnetic field is discussed. The Q-value contributed from the plasma (Q_p) is calculated under the following conditions: i) The plasma is so tenuous that the perturbation theory may be used. ii) The velocity distribution function for plasma electrons is f₀∝v^qexp(−bv^s). iii) The effective collision frequency for momentum transfer is dominantly due to the collisions of an electron with neutral particles and varies with the speed v as ν_c(v)∝v^h. iv) The radius of the plasma is sufficiently smaller than the radius of the cavity.
When Q_p<0, the plasma-cavity system has a possibility of amplification or oscillation. This characteristic depends sensibly on the velocity distribution function for plasma electrons.