Characteristic Performance of a Multi-Aperture Ion Source for Application in Ion Thruster and Material Processing

Abstract

The Multi-aperture and low energy ion sources have applications in ion thrusters and in material processing e.g. etching, ion implantation, sputtering and deposition etc. For these applications, an ion source capable of delivering ion beam (Ar+ / Xe+) of 100 mm diameter, with current up to 200 mA and energies from 0.6keV to 2.0keV is being developed. A magnetic bucket type plasma chamber is utilized to produce Argon plasma with discharge current of 5 – 30A. The ion beam is extracted and accelerated using a two grid extraction system having ∼ 1000 apertures each of diameter 2 mm with an inter-grid spacing of 1 mm. In the present work, the first results obtained on this ion source are being reported. The beam characteristics, namely, current density profiles, angular beam divergence and electrical efficiencies have been measured by a Faraday cup array and sensitive current meters, respectively. The measured angular beam divergence varied from 4 −12 degrees when operated for the entire operational range. Additionally, Doppler shift spectroscopy diagnostics was also performed on Ar ion beam for estimating extracted beam energies and angular beam divergence. Studies showed that the measurement of ion beam current at higher pressures is limited by neutralization of the ion beam via charge exchange phenomena.