Simultaneous closure of multiple high voltage parallel spark channels without switch: A parametric study

Abstract

Results of a detailed parametric study of a self-switched mutually inductively coupled high voltage parallel spark preionizer are presented. The maximal behavior exhibited by the breakdown voltage of the parallel gaps with respect to the number of mutually coupled turns has been explained. It has been found that there exists a threshold rise time of the current pulse beyond which simultaneous closure of the parallel gaps is not possible and that this threshold value is independent of the nature and geometry of the cores used for the mutual coupling. The degree of simultaneity of the closure of the self-switched parallel gaps matched that of the conventional operation of such gaps.

Enhanced efficiency of a mutually coupled parallel spark preioniser

“…Simultaneous closure of the parallel gaps of the preioniser array here without a switch was made possible by ballasting each of the spark channels with inductance and then mutually coupling them to the others through magnetic cores [2]. Subsequent operation of a wide discharge TEA CO 2 laser [3] by placing this preioniser switch only to one side of the discharge clearly identified the decided advantage of this mutually coupled preioniser switch (MCPS) as an effective preconditioning source.…”

On the operation of switch-less transversely excited atmosphere CO2 lasers in the oscillator and amplifier configurations

“…Here, the pre-ionizer, an integral part of the laser head, in addition to preconditioning the inter-electrode volume, performed the role of a switch as well. Simultaneous closure of the parallel gaps of the pre-ionizer was made possible by inductively ballasting each of the spark channels and then mutually coupling them through magnetic cores [4]. Synchronization of the operation of a laser with an event is of utmost importance and in the absence of a conventional switch, e.g., a spark gap or a thyratron, the triggering of such a switch-less laser is not straightforward.…”

Repetitive operation of switchless transverse flow transversely excited atmosphere CO2 lasers

“…[15][16][17][18][19][20][21][22] In this method, the preionising spark array, an integral part of the laser head, was made to serve the dual role; that of a switch as well as of a source of UV photons essential for the preconditioning of the inter-electrode volume. The sequential preionising spark array used in the initial stage of this study was constructed by segmenting the main spark gap into smaller adjustable gaps and then placing them in series along the length and to one side of the discharge.…”

“…The subsequent work has been directed towards gaining a deeper understanding of the characteristics of MCPS (Refs. [17][18][19] that, in turn, allowed perfecting this switchless operation technique by way of extending the operation to include wider discharge width 19 and conventional sized systems 20 that could also be operated in triggered mode. 21,22 Repetitive operation, which was the prime motivation for moving towards switchless configuration, has so far eluded us primarily due to the following reason.…”

“…21,22 Repetitive operation, which was the prime motivation for moving towards switchless configuration, has so far eluded us primarily due to the following reason. As the operating voltage of a switchless laser is governed by the preioniser gap length, 17 in order to have an independent control on the operating voltage of the laser and the composition of the laser gas mixture, the preionisation chamber is isolated from the main discharge by means of LiF windows 16,19,20 that offer high transmission to the UV photons in the 110-130 nm range known to cause effective photo preconditioning. 23 As the contaminated gas in the inter-electrode volume needs to be replenished between two successive pulses to obtain arcfree repetitive operation, 24 transverse gas flow configuration that allows quicker replenishment at low gas flow rates as compared to the longitudinal flow configuration, is desirable.…”