https://doi.org/10.1051/epjconf/201715703013
DC currents collected by a RF biased electrode quasi-parallel to the magnetic field
1 Institut Jean Lamour, Facult des sciences, 54500 Vandoeuvre-les-Nancy, France
2 Max-Planck-Institut fr Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching, Germany
* Corresponding author:eric.faudot@univ-lorraine.fr
Published online: 23 October 2017
Local plasma biasings due to RF sheaths close to ICRF antennas result mainly in a negative DC current collection on the antenna structure. In some specific cases, we may observe positive currents when the ion mobility (seen from the collecting surface) overcomes the electron one or/and when the collecting surface on the antenna side becomes larger than the other end of the flux tube connected to the wall. The typical configuration is when the antenna surface is almost parallel to the magnetic field lines and the other side perpendicular. To test the optimal case where the magnetic field is quasi-parallel to the electrode surface, one needs a linear magnetic configuration as our magnetized RF discharge experiment called Aline. The magnetic field angle is in our case lower than 1 relative to the RF biased surface. The DC current flowing through the discharge has been measured as a function of the magnetic field strength, neutral gas (He) pressure and RF power. The main result is the reversal of the DC current depending on the magnetic field, collision frequency and RF power level.
© The authors, published by EDP Sciences, 2017
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
