Eigenmode interactions in gyrotron electron beams

Small-signal calculations are presented for eigenmode interactions in relativistic electron beams. The interaction mechanism of the Whistler mode with the electron beam is shown to occur over extremely large bandwidths and may be used in millimeter-wave amplifiers or oscillators. The effect of beam temperature is discussed, showing that bandwidth is reduced due to velocity spreads parallel to the applied magnetic field. Preliminary large-signal calculations are presented. Possible oscillations observed in gyrotrons may be due to these eigenmodes.