Avalanche transistor pulser for fast-gated operation of micro-channel plate image-intensifiers

Abstract

Transistors operated in the avalanche mode are employed to generate a 1000 volt 10 to 30 nsec wide pulse with less than 4 nsec rise and fall times. This pulse is resistively attenuated to approximately equal to 270 volts and drives the image intensifier tube which is a load of approximately equal to 200 pf. To reduce stray inductance and capacitance, transistor chips were assembled on a thick-film hybrid substrate. Circuit parameters, operating conditions, and coupling to the microchannel plate image-intensifier (MCPI/sup 2/) tube are described. To provide dc operating voltages and control of transient voltages on the MCPI/sup 2/ tube a resistance-capacitance network has been developed which (a) places the MCPI/sup 2/ output phosphor at ground, (b) provides programmable gains in ''f-stop'' steps, and (c) minimizes voltage transients on the MCPI/sup 2/ tube