- a vacuum tube in which the cathode is heated electrically to cause the emission of electrons by thermal agitation.
Origin of thermionic tube
First recorded in 1925–30
Also called hot-cathode tube.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- An electrical component, typically an electron tube, through which electric current flows via the emission of thermions from a heated cathode.
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