Development of a Radio Frequency Coupled Broad Beam Ion Source for Material Processing

Abstract

The present work presents the development of a radio frequency (RF) broad beam ion source for generating a high brightness ion beam for material processing. The source is able to deliver ion beams energy from 100 to 2000 eV with beam currents from 100 mu A up to 25 mA. The beam divergence does not exceed 8 degrees when using nominally flat grid. The extracted ion current from a plasma source depends on the plasma parameters particularly the electron density and the electron temperature of the plasma. Optical Emission Spectroscopy (OES) is used to determine the plasma electron density and temperature. The effects of argon filling pressures and RF power on electron temperature and density of plasma parameters are investigated. The electron density of argon plasma is between 4x10(11) and 7 x 10(12) cm(-3), whereas electron temperature 0.6 - 5 eV at pressures from 5x10(-4) to 8.5 x 10(-3) mbar over the RF powers deposited within the plasma from 25 to 200 W. The ion source is installed on a homemade accelerating tube. The beam optics is extensively studied with space charge compensation by Transport code. A solenoid magnet located between the ion source and the accelerating tube is used to focus and control the beam divergence. The performance of the accelerating facility is reported and applications for material modification are examined.