M. Blank et al., STUDY OF ROTATING MODES IN HIGH-FREQUENCY WHISPERING-GALLERY MODE GYROTRONS, IEEE transactions on plasma science, 22(5), 1994, pp. 883-888
An investigation of coupling to the two rotations of TE(m,2,1) modes o
f a gyrotron oscillator was made. Experiments were performed on a mega
watt power level, 3 mu s pulsed gyrotron operating at frequencies from
123.5 GHz (TE(13,2,1)) to 153.5 GHz (TE(17,2,1)). Single rotation ope
ration was observed with the electron beam centered in the cavity. The
influence of tube misalignment on rotation mix was studied. The exper
imental results were in good agreement with predictions of linear coup
ling theory for an off axis electron beam. Both experiment and theory
showed that significant misalignments of the beam are possible before
a switch in the rotation direction of the output mode occurs.