| 单词 | dull emitter |
| 释义 | > as lemmasdull emitter dull emitter n. a thermionic valve in which the filament operates at a relatively low temperature, and so does not glow brightly; also, such a filament; also attributive; hence dull-emitting adj. ΚΠ 1922 Wireless World 30 Sept. 858/2 The set has been designed that either R or ‘Dull Emitter’ valves can be fitted, the latter permitting of the operation of the set from dry cells. 1923 Wireless World 5 May 137/2 The dull-emitting filaments of the valves are made from thoriated tungsten and..if thoriated tungsten had not proved useful in electric lamp manufacture, there would not exist to-day the ‘dull-emitter’ valve. 1923 Exper. Wireless Nov. 97/2 The object of the dull emitter is to obtain the same filament emission with only a fraction of the energy previously required to render the ordinary filament sufficiently incandescent. 1970 D. F. Shaw Introd. Electronics (ed. 2) x. 209 Oxide-coated cathodes..glow a dull red and they are therefore called dull emitters, contrasted with tungsten filaments which are bright emitters. < as lemmas |
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