Improvement of high-current large-volume discharge with profiled hollow-cathode electrodes

Journal Article · Tue Apr 01 04:00:00 EST 1997 · IEEE Transactions on Plasma Science

DOI:https://doi.org/10.1109/27.602517· OSTI ID:522419

Chang, J J; Arnold, P A; Warner, B E ^[1]

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1. Lawrence Livermore National Lab., CA (United States)

Filamentary discharge at the electrode of high-power copper vapor lasers prevents stable operation when the buffer gas (Ne) pressures exceeds 30 torr. Experimental evidence indicates that the discharge constriction starts in the cathode fall region. The volumetric power deposition at the cathode fall is estimated to be {approximately}130 MW/cm{sup 3} at 40 torr during a peak discharge current of 2.5 KA. This highly pressure-dependent large thermal loading at cathode fall is likely to initiate thermal instability as pressure increases. This discharge instability can be mitigated by taking advantage of the hollow-cathode effect even for pressures exceeding 100 torr. The authors have designed a large-area electrode with many hollow-cathode grooves spreading over the uniform-field-profile area of the electrode for enhanced electron emission. This unique design lowers the cathode-fall voltage, and as a consequence, reduces the thermal loading at the cathode fall. With this profiled, hollow-cathode electrode, they have successfully extended stable discharge from {approximately}30 to {approximately}100 torr. They believe this profiled electrode design with multiple hollow-cathode grooves will expand hollow-cathode electrodes to many applications that require high-current large-volume discharge at elevated pressures.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 522419
• Journal Information: IEEE Transactions on Plasma Science, Journal Name: IEEE Transactions on Plasma Science Journal Issue: 2 Vol. 25; ISSN ITPSBD; ISSN 0093-3813
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
DESIGN
ELECTRODES
GLOW DISCHARGES
METAL VAPOR LASERS
PERFORMANCE
PRESSURE DEPENDENCE