Study of the structure and deviation from equilibrium in direct current supersonic plasma jets

• Published in: Journal of physics. D, Applied physics Applied physics, 2001-09, Vol.34 (18), p.2862-2874
• Main Authors: Selezneva, S E, Rajabian, M, Gravelle, D, Boulos, M I
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Optical (ultraviolet, visible, infrared) measurements; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; Plasma devices; Plasma diagnostic techniques and instrumentation; Plasma torches
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/34/18/321

Mathematical modeling and optical emission spectroscopy are applied to study the effect of the chamber pressure on the structure and properties of supersonic plasma jets formed by a direct current arc. In this installation, the plasma is created inside a nozzle where the flow is accelerated. As a result, some deviation from thermal and ionization equilibrium can be found, even at the working chamber inlet. In this paper, by means of a two-temperature model, we study the argon jet flow using the data of the emission spectroscopy measurements. It makes realistic assumptions about the inlet boundary conditions. The results show that, when the number pressure is low, a strongly underexpanded jet with a Mach disc is formed. For higher ambient pressure values, the core region of the jet changes to a mildly underexpanded structure with alternating oblique expansion and compression zones. (Author)