Discharge mechanism of the Kyoto University-type microwave plasma cathode or microwave ion source

In this paper the discharge mechanism of the Kyoto University-type microwave plasma cathode is studied. The relationship between the electron-absorbed power pe and electron impact frequency γc is obtained. When B=875 G, pe decreases with the increment of γc. At the same time when γc→0 or γc≪ω, electron cyclotron resonance (ECR) discharge will be set up. When B≳875 G and γc =107–108 s−1, the off-resonance discharge exists. With γc increased up to a certain limit, it follows that when ωz‖γ=ω=(2×3−1/2)1/2ω, a new type of discharge, the so-called double resonance (DR) discharge, occurs. For the Kyoto University-type MPC or MIS, the off-resonance discharge and DR discharge can be satisfied and it is verified by experiment.