Influence of Discharge Voltage on Charged Particles in a Multi-Dipole Device in the Presence of an Ion Collecting Surface

The influence of discharge voltage on ion collecting surfaces in the form of a metal plate and a mesh grid is investigated in a multi-dipole device. In the experiment, a solid metal plate and a mesh grid are placed alternately at one end of the multi-dipole device. It is seen that except for high negative bias, the ion space charge layer in front of the grid gets depleted with the increase in discharge voltage whereas it gets thickened in front of the plate. It is also observed that the electron loss at the cusp (anode current) changes accordingly in both the cases. The increase in discharge voltage can enhance the Bohm speed of ions towards the ion collecting surfaces. Further, the negative potential applied to the ion collecting surfaces lowers the bulk plasma potential, which in turn affects the anode current.