The Back-Lighted Thyratron

Abstract

This chapter reviews a new optically triggered pseudospark-type switch that operates with characteristics that are useful for certain high power, high pulse energy applications. The optically triggered pseudospark described here is referred to as a back lighted thyratron (BLT), a name that is indicative of its method of operation as well as the super-dense glow characteristic of its discharge (Kirkman and Gundersen, 1986; Kirkman et al., 1988a). Optical gating or triggering of high power switches is useful for applications requiring low jitter and/or optical isolation of the trigger. Laser initiated high power, high pulse energy switches previously developed include the laser-triggered spark gap (Pendleton and Guenther, 1965; Guenther and Bettis, 1971). The laser triggering mechanism for the laser triggered spark gap normally utilizes a focused laser which produces a small plasma either at the surface of one electrode (Williams and Guenther, 1990) or in the switch fill gas (by optical breakdown of the gas). Specific electrode photoemissive mechanisms have also been investigated for high pressure spark gap triggering (Harsch et al., 1975). These devices are discussed in more detail in Chapter 3.