A high-impedance, cold-cathode trigger tube

The tube to be described is a cold-cathode, gas-filled tetrode which triggers on extremely low signals. It was developed by the Raytheon Manufacturing Company in cooperation with the Diamond Ordnance Fuze Laboratories. Under pre-firing conditions, the tube passes a very small Townsend current of about 10^-9amp. On application of a firing signal, current in the sensitive gap rises to about 10^-8amperes, then breaks down into a glow discharge which transfers to the main gap in a few microseconds. After firing, conduction currents are limited only by resistance present in the external circuit, and under certain circumstances currents up to 6 amperes can be passed. Typical firing voltages are in the range of 5 to 10 volts for an applied signal of about 500 v/s. Input impedances of 10⁷to 10⁸ohms have been measured for the device.