Krytrons

Krytrons are a class of fast, gas-filled electronic switches used to convert a small control signal into a large, fast electrical pulse. They belong to the family of gas-discharge tubes and are related to thyratrons but are designed for quicker triggering. A krytron contains an anode, a cathode, and one or more control electrodes (trigger or gate). In normal operation the gas is non-conductive; a short trigger pulse ionizes the gas, initiating a rapid discharge that forms a conducting path between the anode and cathode. The device latches on while the current remains above a holding value and resets when the current falls below the holding threshold and the gas de-ionizes.

Krytrons were developed in the mid-20th century for high-speed pulsed-power applications. They have been used in radar transmitters, particle-accelerator timing systems, and other fast-switching circuits, and historically as very fast initiators in certain explosive-charge assemblies. They offer nanosecond-scale switching times and the ability to handle high voltages, but require hermetically sealed packaging, controlled gas mixtures, and careful handling. Performance can degrade from contamination, electrode wear, and mechanical shock.

In modern practice, many applications have moved to solid-state or optically triggered switches, and krytrons are now chiefly confined to specialized facilities and historical study. Their history reflects mid-century approaches to achieving ultra-fast switching and the dual-use concerns associated with high-energy pulse technology.