A compact low-pressure trigatron

The constructional details and operational characteristics of a 10kV 100kA low-pressure switch, developed for use in research on rotating plasmas, are given. This switch, employing a single parallel-plate gap with a triggering pin built into the centre of one electrode, has a concentric cylindrical return path made integral with a current-measuring device. The switch is easily triggerable, operates over a very wide voltage range, has a low inductance, and is virtually silent, both audibly and electrically. From an investigation of the conditions affecting closing time and jitter, it is concluded that the device is feasible for synchronous switching, using several switches in parallel paths. A brief account is given of the development, to date, of a higher-voltage switch suitable for application, in ten parallel paths, to a large capacitor bank. The conducting channel of the switch has been observed by streak photography to spread radially from the trigger with a velocity of 1 2 × 106 cm/s. This value is consistent with that obtained in the measurement of the time variation of switch-gap inductance, for which a technique was developed to isolate the inductive from the non-inductive voltage drop. A theoretical basis of the triggering mechanism is presented.