Release conditions of dust particle from plasma-facing wall in oblique magnetic field

斜行磁場中のプラズマ対向壁からのダスト粒子離脱条件

冨田 幸博*; 河村 学思*; Smirnov, R.*; 滝塚 知典; Tskhakaya, D.*

Tomita, Yukihiro*; Kawamura, Gakushi*; Smirnov, R.*; Takizuka, Tomonori; Tskhakaya, D.*

斜行磁場中の垂直なプラズマ対向壁からの球形ダスト粒子の離脱条件を解析的に調べた。ポアソン方程式か、ダストの離脱力を決めるシース電場を求めた。電場は磁場が壁に平行に近くなるほど減少する。一方プラズマ流は適度な斜行磁場中で大きくなる。強磁場中では、離脱可能ダストの半径は磁場入射が壁に鋭角になるほど大きくなる。また弱磁場中では、中間入射角のとき、すべてのダストが離脱できなくなる。

Release conditions of a spherical dust particle from a plasma-facing vertical wall immersed in an oblique magnetic field are studied analytically. The Poisson's equation is solved in the sheath to obtain the electric field at the wall, which repels the dust particle from the wall. The electric field decreases as the direction of the magnetic field approaches parallel to the wall. On the other hand the ion flow velocity becomes larger at moderate oblique angle than that without magnetic field. It is clarified that in the case of the strong magnetic field the critical dust radius for the release of the dust increases as magnetic field becomes more acute. In the case of the weak magnetic field, the critical radius disappears at the moderate angles of the oblique magnetic field.