Cold cathode

A cold cathode vacuum tube is one in which there is no cathode heater. It contrasts with the heater operated cathodes of vacoum tubes used in early electronics. Cold cathodes somethimes have rare earth coating on them for enhancing electron emission.

In such a tube, glow discharge is usually minimized, in favor of arc discharge. Some important examples include the krytron, sprytron, and ignitron tubes. The most common cold cathode application is in neon signs.