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Thermionic diode

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ravaner

Member
2010-04-16 7:20 am
Hello ! I just discovered in an old document (Dupont Nemours 1952) that Shockley Law is also available for thermionic diode with inverted bias (plate < cathode), this for low currents < 200 µA, and before space charge appears (Child-Lagmuir). I'm very surprised, where is Fermi level ? where are N & P ? If someone knows a demonstration of this, thanks by advance.
 
So what?


...before space charge appears? Cold cathode? In other words in conditions we never use rectifiers?
There are no N & P, just free electrons in the space charge area over the hot cathode.
There may be some leakage going the 'wrong' way, but if so, it's so small it can be effectively ignored.
Actually, I'm no physics master, so can't say for sure.
 

ravaner

Member
2010-04-16 7:20 am
Of courses N & P carriers were a joke :). Thanks for your explanation which shows why we retieve the Boltzmann / Fermi statistic from which Shockley law is issued. For info the diode uses indirect heating (filament) and is parallelized with very high value resistors in a transimpedance amplifier (electrometer).
 
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