Cataphoresis in electric arcs

A two-dimensional numerical model is used to investigate cataphoresis (demi xing driven by electrical fields) in free-burning arcs in mixtures of argon with helium, hydrogen, nitrogen and oxygen at atmospheric pressure. The me thod of inclusion of electrical field effects in the combined diffusion coe fficient treatment of diffusion and demixing is presented. Cataphoresis is found to lead to large increases in helium concentration near the anode in argon-helium arcs and smaller decreases in hydrogen concentration near the axis in argon-hydrogen arcs. There is no significant effect in argon-nitrog en and argon-oxygen arcs. The effects of cataphoresis on other are properti es are generally small and are significant only in argon-helium arcs.