SELF-ADJUSTING ANODE POWER-SUPPLY FOR A GYROTRON

Sydney University's tunable cw gyrotrons use a simplified power supply arrangement to provide the voltages on the gun electrodes. The cathode supply is conventional, but the anode voltage is provided by a single high-value resistor connected between the anode and ground. A small fraction of the electrons in the beam are reflected and the anode automatically finds an optimum operating potential. This arrangement is shown to have lower starting currents. Two advantages follow. It becomes easier to operate low-power gyrotrons with modest power supplies and it becomes easier to achieve higher frequencies by exciting harmonics of the electron cyclotron frequency.