An experimental study of Cd I and Cd II excited-state densities in the interelectrode plasma of a multi-cathode-spot Cd vacuum arc is presented. Current pulses of 1.2 kA peak, 0.65 ms HAFW were passed between 12 mm diameter Cd electrodes spaced 4 mm apart and located in a vacuum chamber. Absolute time and space resolved line intensities were measured using a calibrated lens-monochromator-photomultiplier system. Peak excited-state densities ranging from 1016 to 1019m-3 were observed. Excited-state densities generally decreased as a function of distance from the cathode. The time at which the peak excited-state density occurs increased as a function of distance from the cathode, and decreased as a function of excitation energy. Cd II peaks occurred before Cd I peaks. Cd I excited-state densities and most Cd II excited-state densities could be related empirically through the Boltsmann distribution with distribution temperatures of 0.6-0.9 and 1.1-1.5 eV, respectively, though some Cd II states (6-11g2G) sometimes displayed inverted populations.
|Number of pages||9|
|Journal||Physica B: Physics of Condensed Matter & C: Atomic, Molecular and Plasma Physics, Optics|
|State||Published - Mar 1981|