ISSN:
1089-7623
Quelle:
AIP Digital Archive
Thema:
Physik
,
Elektrotechnik, Elektronik, Nachrichtentechnik
Notizen:
A large area, indirectly heated cathode capable of continuous, high- current electron emission is described. The cathode assembly utilizes an indirectly heated lanthanum molybdenum carbide (LaMo) disk as the thermionic electron emitter. Other cathode shapes are also discussed. The disk cathode emits up to 500 A of electrons at an average of 11 A/cm2 in continuous operation in a plasma discharge. LaMo material is machinable and is not fragile even after extended operation. Careful fabrication and conditioning of the LaMo carbide surface is required. The electron emission capability depends strongly on producing the proper fine grain structure of the molybdenum carbide surface layer to allow adequate diffusion of lanthanum to the surface. Failure to produce the correct surface structure results in intermittent electron emission. The electron emission was not affected by exposure to both air and water during operation, but the emission is poisoned by small amounts of tungsten on the surface. After proper preparation, this intermediate temperature electron emitter is very rugged and has a long lifetime.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.1138439
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