SPECTROSCOPIC STUDIES OF ARGON AND NITROGEN PLASMAS AT REDUCED PRESSURE. TEMPERATURE DISTRIBUTIONS IN PLASMAJETS AND WALL-STABILIZED ARCS.
Final technical rept.,
WARNER AND SWASEY CO FLUSHING N Y
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Stationary plasmas at reduced pressure 0.02 - 0.1 atm. were studied by two different experimental approaches, the plasmajet and the wall-stabilized arc. The nitrogen plasmajet at low pressure is characterized by the appearance of a shock front Mach disc and exhibits pressure and temperature gradients. A method based on the atomic Boltzmann plot in absolute intensity units was used to obtain both the pressure and the temperature distribution. A wall-stabilized arc device with wide confining channel proved to be well suited for obtaining a high current 250 A, low pressure 0.1 atm. argon arc. Core temperatures above 16,000 K were determined and a high degree of ionization observed. The absence of pressure gradients makes the modified wall-stabilized arc a useful tool for research at reduced pressure, but problems of arc stability and symmetry remain to be solved. The wavelengths of several new lines in the argon and nitrogen spectrum were determined, and a strong triplet in the near ultraviolet could be classified as belonging to the transition 3s 2P - 5p 2D of N I. Author