Net Emission Coefficient of Plasma Excited in the Electrical Discharge Machining Through Liquid Nitrogen Dielectric Medium

In the enthalpy conservation equation of plasma model for the arc plasma columns based upon fluid description, a term appears as radiation loss which is a sink term. The purpose of this study is to calculate this radiative heat loss for electrical discharge machining (EDM) arc plasmas in the liquid nitrogen dielectric medium, using method of net emission coefficient (NEC). Assuming cylindrical, in local thermodynamic equilibrium and isothermal plasma, the NEC is calculated for two pressures of 0.1 and 1 MPa, in the working temperature of EDM plasmas range between 5500 and 10 000 K, and according to the EDM plasmas radius. Emissions of atomic lines as well as continuum radiations are considered as the origins of the NEC. The line shapes in this calculation are given by convolution of Doppler and Lorentz profiles, resulting in a simplified Voigt profile. The overlapping lines are also taken into account. Presented results for NEC can serve as input data for various numerical models of EDM process.