Effects of Multi-Species Ions on Sheath and Presheath in a Magnetic Field Decreasing toward a Wall

In the divertor region, the plasma contains deuterium (D) ion and tritium (T) ion in an open magnetic field. The effect of D ion and T ion on the electric potential near the wall in plasma with magnetic field decreasing toward a wall is investigated analytically. The distribution of the electric potential is obtained by plasma-sheath equation, where D ion and T ion are considered. The potential distribution depends on the parameters such as the profile of the magnetic field, the temperatures of D ion and T ion, and the amount rate of T ion to D ion. The particle distribution also is shown.