Investigation of gaseous electron multipliers with magnesium photocathodes for optical triggering of back-lighted thyratrons

Summary form only given. Developing reliable and compact optical triggering systems for back-lighted thyratrons (BLTs), light-activated pseudospark switches is of interest for applications of compact pulsed power. Investigation of the electron multiplication methods is crucial for utilization of low-intensity light sources, including ultraviolet (UV) light emitting diodes (LEDs), as optical sources for triggering BLTs. Recent advances on gaseous electron multipliers(GEMs) whose operation is based on gas multiplication within small, sub-millimeter to millimeter diameter holes has shown multiplication gains of 10³ in both atmospheric and low pressure gas mixtures and noble gases.In this work, we present investigation of GEM type triggering units with magnesium photocathodes for triggering BLTs. Quantum efficiency (QE) of magnesium under BLT relevant pressure conditions (upto 100 mTorr) were measured to be 10⁵. Higher quantum yield was demonstrated for utilization of Mg photocathode compared to Cu and Mo photocathodes. Measurements of the gaseous electron multiplication in argon and helium within the pressure range of 200 mTorr to 1 Torr are presented. Possible schemes for integration of such electron multiplier units with metal photocathode materials to the switch are discussed.