Pulse selection and shaping based on gas breakdown

A new method of pulse selection and shaping is described, utilizing the reflection and attenuation of a gas breakdown event. Using 10.6-µm wavelength radiation breakdown, plasma reflectivities of 4-8% were measured and the reflected pulses showed a risetime faster than the 3.1-nsec response time of the detection system. Calculations of the time-dependent growth of the electron concentration leading up to breakdown, together with a simple model of the plasma reflectivity, predict pulse risetimes of 4 psec and 0.15 nsec for breakdown induced by ramping pulses of 1-nsec and 100-nsec duration, respectively. Experimental conditions favoring the attainment of these fast risetimes. are discussed.