Instant Start Thyratron.

An instant starting hydrogen thyratron is described which incorporates a helical cathode requiring no warm-up time, no stand-by power and no separate heater power supply. The cathode is a self-heating electrode comprised of a low impregnated type cathode having high cold pulse-emission capability. At cold start, the cathode provides sufficient emission capability to trigger readily and to attain full operating temperature via plasma heating effects and its own resistive dissipation. After shut-down, the cathode remains active in readiness for the next cold start, a cycle which can be repeated as often as desired. A specific implementation of the helical cathode comprises tungsten impregnated with barium calcium aluminate.