Voltage transients due to arc extinction

High transient voltages may be developed in equipment associated with gas conduction tubes when there is a sudden cessation or change in the magnitude of the current that is being conducted through the tube. The conditions for the occurrence of this phenomenon have received considerable attention from those working in the field of gas conduction tubes as well as those who have applied such devices. Three conditions of operation of gas conduction devices have been recognized as contributing or being capable of creating the rapid rate of current change that is necessary to generate the high voltages observed: 1. cathode-spot extinction, 2. arc extinction, or gas ¿starvation¿ as it is sometimes called, and 3. the pinch effect. The pinch effect occurs when the current through the discharge reaches a sufficient magnitude to cause the conduction electrons to be pressed into a tight spiral because of the force of the self-induced magnetic field on the electron trajectory. This phenomenon is receiving considerable attention in the controlled thermal nuclear work that is currently being undertaken. Of the three, the pinch effect has not been demonstrated to be a contributing factor in the generation of transient voltages under normal conditions of operation and will not be considered further in this paper.