Radial characterization of an ion beam in a deflected magnetic nozzle

Abstract

The radial characterization of an ion beam generated in a magnetically steered radio-frequency (RF) plasma source is presented. In the symmetrical magnetic nozzle (MN) configuration, radial profiles of the ion saturation current obtained with a planar Langmuir probe show a double-peaked profile. The same behaviour is confirmed by the radial measurements of the total ion current and the ion energy distribution functions (IEDFs) obtained with a retarding field energy analyzer. The IEDFs also show the presence of an ion beam centred at r = -2 cm. On the contrary, radial measurements taken with a magnetic nozzle deflected on the r - z plane exhibit a single-peaked profile with both the local ion population and the ion beam centred at r = -5 cm, in the direction of the MN orientation. It is shown that the ion beam location is changed as a result of a deflected magnetic nozzle, and that it follows the direction of increasing radial magnetic field.