Experimental and Theoretical Studies of a Nitrogen Arc With Copper Evaporation From the Anode: RIA
Kasra Etemadi Principal Investigator
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This proposal is concerned with experimental and theoretical studies of thermal plasmas, in particular with the impact of anode evaporation to the anode region of a high intensity nitrogen arc. An improved emission spectroscopic technique will be utilized to measure the temperature and the vapor density distribution of the anode material (copper). In a two-step process the unresolved (0,0) emission band of molecules at 3914.4 A and the spectral line of CuI at 5218.2 A are chosen for the measurements. The plasma properties will be also determined by the relative line intensity method of CuI using 5105.5, 5153.2, 5218.2, 5700.2, and 5782.1 A spectral lines. Holographic interferometry will be used for flow visualization and for temperature measurements in the lower temperature regions (in the absence of turbulence and in the presence of an axisymmetrical plasma). An already existing computer program for the modeling of a mixture of argon and copper thermal plasma will be modified for a nitrogen-copper free burning arc. The thermodynamic and transport properties of the nitrogen-copper plasma required for the modeling will be calculated by a program written for a general multicomponent two-temperature plasma. In the intended study the plasma is assumed to be optically thin and in the state of Local Thermodynamic Equilibrium. Thermal plasmas can be applied for melting, cutting, welding and refining materials, and they play an important role in high power interrupters, arc lamps, reduction metallurgy and plasma spraying. A change in the anode geometry due to evaporation can have a deleterious affect on the desired heat and mass transfer and can damage switching devices. By applying advanced optical methods to determine the temperature and flow characteristics of the plasma in the vicinity of the electrodes, the evaporation process can be better understood.