https://doi.org/10.1051/epjconf/201715703025
Feasibility study of Passive Optical Emission Spectroscopy for the electric field measurements in IShTAR
1 Ghent University, Department of Applied Physics, Ghent, Belgium
2 Max-Planck-Institut für Plasmaphysik, Garching, Germany
3 LPP-ERM-KMS, TEC partner, Brussels, Belgium
4 Université de Lorraine, Nancy, France
5 Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
* e-mail: ana.kostic@ipp.mpg.de
Published online: 23 October 2017
Direct, non-intrusive, measurements of electric fields are essential for understanding the RF-sheath physics. This is especially true in the case of the ICRF antenna - plasma edge interaction in fusion devices. The rectification of the RF-fields near the plasma-facing components of an antenna leads to the development of DC electric fields that accelerate the ions from the plasma towards the antennas’ plasma-facing components, enhancing physical sputtering and release of impurities. IShTAR is a device dedicated to the investigation of the plasma - antenna interactions in tokamak edge-like conditions. It has a simplified geometry and enables an easy access and fast modifications, which makes it a suitable environment to develop diagnostics for electric field measurements.
This paper presents the observed Stark effect on He I spectral line profile, with passive optical emission spectroscopy. To be able to fully control the operating parameters, at this initial stage, the measurements are conducted on a simple DC-biased electrode rather than the ICRF antenna. Measured line profiles are compared with the analytical models of the Stark effect in magnetised helium plasma that, as a result of the good fit, provide the electric field strength.
© 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.
