Ionization Time of Thyratrons

Abstract

Seventeen thyratron and grid-glow tubes, representing 12 different types, have been tested, and their ionization times have been measured with a cold-cathode-type oscillograph. These ionization times vary over a wide range, from a fraction of a microsecond to several hundred microseconds. Ionization time has been found empirically to be inversely proportional to grid overvoltage. Grid over- voltage is defined as the difference between the potential applied to the grid and the critical potential necessary to prevent firing. Argon, neon, and mercury-vapor tubes were included in the test. Mercury temperature was found to have no appreciable effect on the ionization time with low grid overvoltages. All mercury-vapor tubes have similar ionization-time characteristics. In fact, tubes of the same type and manufacture sometimes differed from each other more than one tube differed from another tube of different construction and manufacture.

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