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
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.