An enclosed spark-gap for overvoltage protection

In radar circuits, if, under fault conditions, the modulator cable is not discharged, overvoltages may arise which are dangerous to components. The paper describes a spark-gap employed as a protective device. Such a gap should break down without time-lag at a little above the circuit-operating voltage. De-ionization should be rapid, as voltage pulses may recur at up to 5 000 per second. Breakdown voltage should be unaffected by previous breakdowns, and should be independent of atmospheric pressure and temperature. The sealed-off, hydrogen-tilled spark-gap described substantially satisfies these conditions. Breakdown voltages of 5 and 16 kV were standardized, but samples for experimental work were supplied up to 22 kV. Pressures up to 2 atmospheres of hydrogen were employed. A robust design enclosed in a ceramic envelope also is described.