Avalanche Transistor Pulser for Fast-Gated Operation of Microchannel Plate Image-Intensifiers

Transistors operated in the avalanche mode are employed to generate a 1000 volt 10 to 30 nsec wide pulse with < 4 nsec rise and fall times. This pulse is resistively attenuated to ≃ 270 volts and drives the image intensifier tube which is a load of ≃ 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 (MCPI2) tube are described. To provide dc operating voltages and control of transient voltages on the MCPI2 tube a resistance-capacitance network has been developed which (a) places the MCPI2 output phosphor at ground, (b) provides programmable gains in "f-stop" steps, and (c) minimizes voltage transients on the MCPI2 tube.