This title appears in the Scientific Report : 2018 

Numerical estimate of themulti-species ion sound speed of Langmuir probe interpretations inedge plasmas of Wendelstein 7-X
Cosfeld, J.
Rack, M. / Reiter, D. / Drews, P. / Blackwell, B. / Jakubowski, M. / Niemann, H. / Zhang, D. / Feng, Y. / Wendelstein 7-x Team
Plasmaphysik; IEK-4
Jülich Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag 2018
20 p.
Berichte des Forschungszentrums Jülich 4414
Please use the identifier: in citations.
The three-dimensional Monte Carlo transport code package EMC3-EIRENE has been widely applied as edge plasma analysis tool for more than a decadenow, resulting in successful validation applications against various measured trendsseen in stellerator plasma boundaries. Here we apply this code package for Wendelstein7-X discharges in interpretive mode. We are able to clearly identify (and correct)an earlier experimental hardware probe misalignment, which had led to an otherwiseunresolvable inconsistency between experimentally constrained EMC3-EIRENE simulationsand mid-plane Langmuir probe measurements.Today W7-X plasma discharges still lack diagnostics to directly measure some importantedge plasma properties, such as the spatial distribution of the effective chargestate. Here EMC3-EIRENE simulations are applied in an iterative process to reconstructthese computationally. Earlier assumptions on the effective charge state distributionfor reported Langmuir probe measurement have to be revised. Re-processingof up- and down-stream Langmuir probe measurements with code interpreted spatialprofiles of the effective charge state now lead to overall improved physical consistency.