Operation of a tunable gyrotron at the second harmonic of the electron cyclotron frequency

The University of Sydney's GYROTRON IV is a single CW source of low-power millimetre-submillimetre radiation that can be tuned across a broad frequency range from below 100 GHz to above 500 GHz. The higher frequencies are obtained when the gyrotron operates at the second harmonic of the electron cyclotron frequency. The conditions for achieving second harmonic operation are discussed.