Effects of a Weak Transverse Magnetic Field and a Spatial Potential on Negative Ion Transport in Negative Ion Sources

The effects of the weak magnetic field on the negative ion ( ) extraction in a negative ion source have been studied by means of a two-dimensional electrostatic particle simulation. A particle-in-cell (PIC) model is used which simulates the motion of the charged particles in their self-consistent electric field. Since most electrons are magnetized by the weak magnetic field, it is shown that more ions arrive instead of electrons in the region close to the plasma grid in order to ensure the plasma neutrality. In the present article, the effect of the electron diffusion across the weak magnetic field is also taken into account. Although the electron diffusion effects weaken the difference of the dynamics between electrons and ions, the presence of the magnetic field still has a large contribution to the enhancement of the extraction. H