Title :
Measurement of cathode spot parameters with pulsed laser diagnostics
Author :
Vogel, Nadja ; Heinzinger, Jan ; Cichos, Frank
Author_Institution :
Dept. of Phys., Tech. Univ. Chemnitz, Germany
fDate :
12/1/1995 12:00:00 AM
Abstract :
The cathode spot formation in air within the first 170 ns was investigated by laser absorption photography and ps-pulse interferometry. The discharge was initiated between electrodes made from Ag or Pd with cathode-anode distance below 300 μm, the arc duration was some milliseconds, and the arc current 5-10 A. Picosecond holographic interferometry and momentary absorption photography yielded spatial-temporal density distributions in the ignition phase of the cathode spot. An absolute electron density value on the order of 4×1026 m-3 has been found. In contrast to vacuum, the cathode spot plasmas broaden little with increasing distance from the cathode, thus narrow plasma channels are observed in the vicinity of the cathode surface having diameters <20 μm
Keywords :
arcs (electric); cathodes; electron density; high-speed optical techniques; holographic interferometry; ignition; photography; plasma density; plasma diagnostics; plasma production by laser; plasma shock waves; plasma waves; shock waves; 300 mum; 5 to 10 A; Ag; Pd; absolute electron density value; air; arc current; arc duration; cathode spot; cathode spot formation; cathode spot parameters; cathode spot plasmas; cathode surface; cathode-anode distance; ignition phase; laser absorption photography; momentary absorption photography; picosecond holographic interferometry; plasma channel; ps-pulse interferometry; pulsed laser diagnostics; spatial-temporal density distributions; Absorption; Cathodes; Electrodes; Holography; Interferometry; Optical pulses; Partial discharges; Photography; Plasma density; Pulse measurements;
Journal_Title :
Plasma Science, IEEE Transactions on
