Studies of self‐consistent field structure in a quasioptical gyrotron

The presence of an electron beam in a quasioptical gyrotron cavity alters the structure of the fields from that of the empty cavity. A computer code has been written that calculates this alteration for either an electron beam or a thin dielectric tube placed in the cavity. Experiments measuring the quality factor of such a cavity were performed for the case of a dielectric tube and the results agree with the predictions of the code. Simulations of the case of an electron beam indicate that self‐consistent effects can be made small, in that almost all the power leaves the cavity in a symmetric Gaussian‐like mode, provided the resonator parameters are chosen carefully.