Abstract
Effects of an externally applied magnetic field on CO2 and SF6 arc plasmas are examined by three-dimensional time-dependent magnetohydrodynamic numerical analysis. The present numerical analysis is carried out for a cylindrical-shaped simple chamber filled with CO2 or SF6 under the condition of direct electric current and uniform magnetic field. The dependence of thermodynamic and transport properties, and emission coefficients of each gas on temperature and pressure is taken into account in the numerical analysis. Numerical results show that thermal constriction of arc column by applying a magnetic field is more clearly apparent in the case of CO2. The heat transfer from arc plasma to surrounding gas for CO2 is more intense than that for SF6. This is because the rotational speed of arc plasma for CO2 is about two times faster than that for SF6, and also the thermal conductivity of CO2 at the edge of arc column is higher than SF6. In the case of CO2, both of arc voltage and pressure are more greatly increased by applying the magnetic field compared with the case of SF6.
