Solid-state techniques are making inroads into one of the few remaining areas where, until now, valves have remained unchallenged - high voltage technology.
Damage to transistors and so on when flash-over or other overload conditions occur has been one of the major problems in designing transistorised high voltage supplies.
In one remedy, in the case of a 25kV supply, the high voltage DC line is obtained by means of an eight-stage Cockroft-Walton multiplier. This means that the AC feed to the multiplier is of a relatively low value and at relatively low impedance due to regenerative feedback being applied to the HF oscillator from which the AC is derived.
Since the feedback voltage is proportional to the voltage across the load, short circuits and flashovers mean that the feedback is correspondingly small and damage to the transistor is avoided.
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