Shot noise in gyroklystrons

Expressions for the shot noise generated in the input cavity of a gyroklystron are calculated. Results are given for noise amplitude, noise temperature, and phase noise. For a beam of uncorrelated electrons the noise temperature scales as the beam energy. An estimate of the role of collective effects on the noise properties is given. These might either decrease or increase the noise level. It is expected that the shot noise in an actual device will depend in a sensitive way on the profile of magnetic field in the compression region preceding the input cavity.