thermionic
adjective
therm·ion·ic ˌthər-(ˌ)mī-ˈä-nik 
: relating to, using, or being the emission of charged particles (such as electrons) by an incandescent material
Example Sentences
Recent Examples on the Web The thermionic diode heat engine invented by Nottingham and Hatsopoulos in the 1950s finally went all the way and produced power with no moving parts. 
Charles A. Berg, The New York Review of Books, 6 June 2019 The thermionic diode heat engine invented by Nottingham and Hatsopoulos in the 1950s finally went all the way and produced power with no moving parts. Charles A. Berg, The New York Review of Books, 6 June 2019
Charles A. Berg, The New York Review of Books, 6 June 2019 The thermionic diode heat engine invented by Nottingham and Hatsopoulos in the 1950s finally went all the way and produced power with no moving parts. Charles A. Berg, The New York Review of Books, 6 June 2019 Word History
Etymology
thermion charged particle from an incandescent source, from therm- + ion
First Known Use
1909, in the meaning defined above