The Effects of Graphite Particles on arc Plasma Characteristics

The interaction between graphite particles and argon plasma in the arc torch is investigated by numerical simulations. The addition of carbon vapor improves the specific heat capacity, electrical conductivity and thermal conductivity of plasma, and decreases its viscosity. It is important to note that the changes in the thermodynamic and transport properties of the plasma substantially affect the arc plasma temperature and the spatial distribution of the carbon vapor concentration. As the graphite particle feed rate increases, the arc will be continuously contracted and the arc electric current density will be increased. The carbon vapor enhances the plasma electrical conductivity, but the heat absorption by the particles reduces the temperature of the plasma, eventually leading to decreased the electrical conductivity. Both result in ascent of the electric field of the arc, so that increase the arc voltage. In addition, the heat flux radial distribution of radiation-absorption of the particles is much less than the thermal conduction, but the particles near the wall absorb radiation from arc region, so that reduce energy loss of the radiation of the arc column.