Trigatron

a cold-electrode spark-gap switch in which the discharge between the two main electrodes is initiated by a trigger voltage pulse applied to the third (trigger) electrode. A triga-tron may have an open design, with the discharge occurring in air, or may be hermetically sealed, with the electrodes being enclosed in a gas-filled glass or ceramic envelope at a pressure of 10–10³ kilonewtons/m². The trigger electrode is located either between the main electrodes or in the hollow core of one of the main electrodes. By the mid–1970’s, the term “trigatron” was practically superseded in the USSR by the broader term “controlled discharger” (upravliaemyi razriadnik).