31. This occurs through devices such as a hollow cathode plasma contactors, thermionic cathodes, and field emitter arrays. 32. This phenomenon, known as thermionics , is not a new discovery _ Thomas Edison spotted it back in 1883. 33. After receiving his M . A . in 1905, he began research on thermionic emission in the Cavendish Laboratory. 34. The thermionic triode, a vacuum tube invented in 1907, enabled amplified radio technology and long-distance telephony. 35. The same year John Ambrose Fleming invented the Fleming valve or thermionic diode which could also rectify an AM signal. 36. The thermal converters ( whose output power is a function of a temperature differential ) include thermoelectric and thermionic generators. 37. The "'EL34 "'is a thermionic valve or vacuum tube of the power pentode type. 38. Hot metal will emit electron via Thermionic emission . talk ) 17 : 48, 18 November 2008 ( UTC) 39. Of course, the photoelectric effect may be used in the retarding mode, as with the thermionic apparatus described above. 40. He invented the thermionic diode 1873 ( this was later given alternate credit to Edison's assistant WJ Hammer ).
