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: firstname.lastname@example.org
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
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