Influence of Background Plasma on Operation Efficiency of High-Power CW Gyrotrons

Inhalt:
A slow wave non-linear single mode stationary theory describing influence of background plasma which occurs in the gyrotron cavity on gyrotron operation has been developed. It is shown that the main effects of a low density background plasma on efficiency are concerned with decreasing the mismatch between operational and cyclotron frequencies and decreasing the beam-wave coupling coefficient. Numerical calculations are performed for the 140 GHz 1 MW CW gyrotron developed in Karlsruhe for fusion applications. Interpretation of some experimental effects which are not yet clearly understood is addressed.