Measurements and Modeling of Plasma Arc

The electron temperature of a helium vacuum arc discharge has been estimated by using of optical emission spectroscopy (OES) technique and assuming a local thermodynamic equilibrium (LTE) model. A data acquisition card with LABVIEW program software is used to pick up data to computer system. The measurements have been evaluated at different conditions of current, pressure and distance between anode and cathode. Temperature calculations have been done by using of two methods: line intensity versus excitation method and relative intensities of two lines method. The behavior of temperature with current, pressure and distance by the two ways have been compared. Simple software has been done using MATLAB program to evaluate the electron temperature by using the line intensity versus excitation method. It has been found that electron temperature decreased from 0.72 and 0.96 eV to 0.29 and 0.59 eV with increasing distance between anode and cathode from 4 mm to 12 mm, respectively, at constant pressure and current of 5 torr and 20 A, respectively. The electron temperature increased from 0.21 and 0.3 to 0.67 and 0.94 eV by increasing the arc current from 15 to 45 A, respectively, at constant distance between the two electrodes and constant pressure, 4 mm and 0.5 torr, respectively. It has been found that the electron temperature decreased from 0.57 and 2.3 to a 0.21 and 0.8 eV with increasing pressure from 0.1 to 1 torr, respectively, where the current and the distance between the two electrodes are constant at 25A and 4mm. Finally a mathematical model has been done to interpret the experimental results, and to describe the cathode region of the vacuum arc discharge.