Preliminary results of a broad beam RF ion source with electron plasma interaction

Abstract

A new design of a broad beam RF ion source is made to deliver currents of 100 /spl mu/A up to 30 mA with extraction voltages 200 V up to 2 kV. Its plasma intensifying system is made with both addition of electrons from an immersed filament in the discharge and axial magnetic field of 70 up to 300 G. Uniform beam density distribution is made with a planner graphite cathode which has a number of holes of varying diameter arranged to produce perveance matching with the normal Gaussian distribution of the beam density variation of the output current is studied with the variation of extraction magnetic field intensity, discharge pressure and electron injection into the plasma. The influence of electron injection into the plasma is found to have a great effect on increasing the extracted current to about four times its value without electron injection. The increase of extraction voltage is limited with the use of electron injection at V/sub ex/>2kV due to the presence of breakdown inside the discharge tube.