Radial characterization of an ion beam in a deflected magnetic nozzle
Antonella Caldarelli, Félicien Filleul, Christine Charles, Rod Boswell, Nicholas J. Rattenbury, John Cater
Abstract
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 $$r = -2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>r</mml:mi><mml:mo>=</mml:mo><mml:mo>-</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:math> cm. On the contrary, radial measurements taken with a magnetic nozzle deflected on the $$r - z$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>r</mml:mi><mml:mo>-</mml:mo><mml:mi>z</mml:mi></mml:mrow></mml:math> plane exhibit a single-peaked profile with both the local ion population and the ion beam centred at $$r = -5$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>r</mml:mi><mml:mo>=</mml:mo><mml:mo>-</mml:mo><mml:mn>5</mml:mn></mml:mrow></mml:math> 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.