Experimental studies of a self-synchronising, multi pin-plane, corona stabilisation closing switch

A very high repetition rate closing switch is an essential element of all compact pulsed power sources for RF applications. The self inductance of the switch should be low and its design such that would allow its proper integration within a transmission line without introducing too much of a disturbance in the characteristic impedance. The paper presents research on a closing switch design developed a few years ago at Loughborough using a multi-pin/plane arrangement and based on corona stabilisation. The idea is that if synchronised operation of the multi-pin closing switch can be demonstrated, it will minimise the inductance introduced into the circuit to well below that of an equivalent single pin switch with another important advantage being that its implementation into a coaxial transmission line would not cause any impedance mismatch. The main aim of this research was therefore to develop a switch in which as many of the pin-plane gaps as possible are made to close simultaneously. This is not possible with a simple collection of parallel-connected conventional spark-gaps, and the corona stabilisation phenomenon was therefore adopted as a means of demonstrating simultaneous multi-pin operation. Initially the paper presents results from an initial study, related to determining the optimum number of pins necessary in the corona switch. Following this, results are reported and commented on from studies of the simultaneity of the pin-plane closure. Presentation of these results is followed by a detailed spectroscopic investigation of the plasma formed during activation of a pin-plan switch. The paper ends with conclusions from the work and the suggested way ahead.