MULTIPLY-CHARGED ION-TRANSPORT IN FREE-BOUNDARY VACUUM-ARC PLASMA-JET

The free boundary plasma arc jet expansion was analyzed based on a two -dimensional hydrodynamic model. The plasma jet expansion was modeled using the sourceless steady-state hydrodynamic equations, where the pl asma free boundary was determined self-consistently. Due to the existe nce of an electric field in the quasineutral plasma the different char ged ion species can be spatially separated. It was found that the mean charge state distribution is strongly nonuniform with a tendency for the highly charged species to appear near the plasma jet boundary regi on. Along the center line the density of singly charged ions falls off by about four times while the density of fourfold charged ions drops by more than 100 times. The radial charge state distribution becomes m ore nonuniform with increasing magnetic field. Good qualitative agreem ent between calculated and experimental radial distributions of differ ent charged species was obtained. (C) 1998 American Institute of Physi cs. [S0021-8979(98)07323-X]