Crowbar circuit for linear beam device having multi-stage depressed collector

Abstract

A linear beam device having a multi-stage depressed collector is provided with a single crowbar circuit that quickly removes all voltages from the collector electrodes upon detection of an arc between the collector electrodes. The linear beam device comprises a cathode and an anode spaced therefrom that are operable to form and accelerate an electron beam. A collector having a plurality of successive collector electrodes is arranged downstream from the anode to collect electrons of the electron beam. At least one power supply is coupled to the collector and provides a plurality of distinct voltage levels to respective ones of the collector electrodes. The power supply comprises a plurality of serially coupled filter capacitors, with each one of the filter capacitors being charged to a respective difference between adjacent ones of the distinct voltage levels. A crowbar circuit is coupled across the plurality of filter capacitors. The crowbar circuit reduces the total voltage across the plurality of filter capacitors to zero upon detection of an arc between any two of the collector electrodes. According to an embodiment of the invention, the power supply further comprises a plurality of diodes respectively coupled across the plurality of serially coupled filter capacitors. The diodes prevent reversal of voltage of a corresponding one of the filter capacitors upon operation of the crowbar circuit.