Correlation of current quenching and occurrence of metal vapor in a pseudospark discharge
- Univ. of Erlangen-Nuernberg, Erlangen (Germany). Physics Dept.
Concerning the technical properties of a high current switch, it is very important to investigate the erosion of the electrodes. Looking at the erosion rates of about 10 {micro}g/C that were measured for special parameter ranges of the pseudospark discharge it is obvious that a lot of metal vapor is present and so detectable during the discharge. The quenching phenomenon, i.e., a sudden interrupt of the discharge current, was investigated in a pseudospark discharge with charging voltage of 2.5 kV, maximum current of 2 kA and discharge duration of 3 {micro}s. The working gas was hydrogen at a pressure of 40 Pa. Concerning electrode material and geometric parameters, molybdenum electrodes were chosen with hole diameters of 5 mm; the electrode distance was 3 mm. In this parameter range, a temporal correlation of current quenching and the occurrence of metal vapor could be detected by means of time-resolved optical spectroscopy. With each current interruption a sudden increase of emission from neutral molybdenum atoms as well as an increase of cathode spot emission, which is spatially localized on the cathode, occurs. Also oxygen ions were observed which show a similar time-dependence, however with a significant delay of the order of 200 ns. The results are discussed in the scope of the mechanism proposed for quenching, i.e., ion depletion in the plasma boundary layer, and the mechanisms occurring in the high current phase of a pseudospark discharge.
- OSTI ID:
- 118943
- Journal Information:
- IEEE Transactions on Plasma Science, Journal Name: IEEE Transactions on Plasma Science Journal Issue: 3 Vol. 23; ISSN ITPSBD; ISSN 0093-3813
- Country of Publication:
- United States
- Language:
- English
Similar Records
Test of SiC-electrodes in a high current pseudospark switch
Electron emission from pseudospark cathodes