Plasma-Cavity Systemによる負吸収の可能性

It is discussed that the cylindrical cavity of a reflection type, coaxial with a plasma column along the static magnetic field may amplify the incident wave. The Q-value contributed by the plasma (Qp) is calculated under the following conditions : i) The plasma is so tenuous that the perturbation theory is used.ii) The velocity distribution function of plasma electrons is as follows : f° (v) ∝ vq exp (-bys).iii) The effective collision frequency for momentum transfer is dominantly due to the collision of electron with neutral particles and varies with the speed v as νc (v) ∝vh.iV) The radius of the plasma is sufficiently smaller than the radius of the cavity. In the case of Qp>0, the incident wave is always attenuated by the plasma-cavity system. However, when Qp<0, the plasma-cavity system has a possibility of amplification or oscillation. This Characteristic of the plasma-cavity system depends sensibly on the velocity distribution function of plasma electrons.