a mercury-arc rectifier controlled by a subsidiary electrode, the igniter, partially immersed in a mercury cathode. A current passed between igniter and cathode forms a hot spot sufficient to strike an arc between cathode and anode
Word origin
C20: from igniter + electron
ignitron in American English
(ɪgˈnaɪˌtrɑn)
noun
a type of mercury-arc rectifier tube having a mercury-pool cathode and a single graphite anode: when a current is passed through an igniter rod into the pool, the mercury vapor is ionized and an arc starts between the cathode and anode: used in resistance welders, the control equipment for much high-energy research apparatus, etc.