DocumentCode :
3235256
Title :
Breakdown characteristics and conditioning of carbon and refractory metal electrodes
Author :
Goebel, Dan M.
Author_Institution :
Jet Propulsion Lab., California Inst. of Technol., Pasadena, CA
fYear :
2004
fDate :
23-26 May 2004
Firstpage :
1
Lastpage :
4
Abstract :
High voltage carbon and refractory metal electrodes employed in devices used in space, such as ion thrusters and traveling wave tubes, can be easily damaged by electrical breakdown and arcing events. Modification of the electrode surfaces due to these events can impact the voltage hold off capability of the surfaces, which could lead to additional arcing, further damage, and the potential for device failure. On the cathode-potential surface, the arc energy is deposited by all of the processes at the surface ultimately responsible for net electron emission, such as melting, vapor and paniculate formation, sputtering, ion bombardment, etc. On the anode-potential surface, the energy is deposited from the plasma or electron stream that crosses the gap, which causes surface damage by local heating. In spite of this energy dependence on the damage, many systems that use arc discharges characterize the amount of material removed from the surfaces and the lifetime of the device for voltage hold-off by the amount of current that passes through the arc, or the "Coulomb-rating". The results of a series of tests that were performed on the voltage hold off capability and damage to carbon-carbon composite surfaces and molybdenum surfaces due to induced arcing will be presented and discussed. Damage to the surfaces was characterized by the field emission performance after the arc initiation and SEM photographs for the different energy and coulomb-transfer arc conditions. Both conditioning and damage to the surfaces were observed, and will be related to the characteristics of the electrical breakdown
Keywords :
arcs (electric); carbon; composite materials; electric breakdown; electrodes; molybdenum; refractories; scanning electron microscopy; Coulomb-rating; Coulomb-transfer arc conditions; SEM photographs; anode-potential surface; arc discharge; arc energy; arcing events; breakdown characteristics; carbon conditioning; carbon-carbon composite surfaces; cathode-potential surface; device failure; electrical breakdown; electrode surfaces; electron stream; field emission performance; high voltage carbon; ion thrusters; molybdenum surfaces; net electron emission; plasma stream; refractory metal electrodes; surface damage; traveling wave tubes; voltage hold off capability; Breakdown voltage; Electric breakdown; Electrodes; Electron emission; Heating; Plasma devices; Plasma materials processing; Space exploration; Sputtering; Surface discharges;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Power Modulator Symposium, 2004 and 2004 High-Voltage Workshop. Conference Record of the Twenty-Sixth International
Conference_Location :
San Francisco, CA
Print_ISBN :
0-7803-8586-1
Type :
conf
DOI :
10.1109/MODSYM.2004.1433490
Filename :
1433490
Link To Document :
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