Electric Potential in Volume Produced Negative Ion Sources with Magnetic Field Increasing toward a Wall

Abstract

Distribution of electric potential near the wall in the volume produced negative ion source with the magnetic field increasing toward the wall such as the cusp magnetic field is investigated analytically. The plasma-sheath equation that gives the electric potential in the plasma region and the sheath region near the wall is derived analytically and the potential distribution near the wall is obtained by solving the plasma-sheath equation. Effects of the degree of increase of the magnetic field, the production amount of volume produced negative ion, and the ion temperature on the distributions of electric potential are shown.