The Langmuir probe system in the Wendelstein 7-X test divertor

L. Rudischhauser*, M. Endler, U. Höfel, K. C. Hammond, J. P. Kallmeyer, B. D. Blackwell

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    16 Citations (Scopus)

    Abstract

    The design and evaluation of the Langmuir probe system used in the first divertor operation phase of Wendelstein 7-X is described. The probes are integrated into the target plates and have individually facetted surfaces to keep the angle of incidence of the magnetic field within an appropriate range for different magnetic configurations. Multiple models for the derivation of plasma parameters from current-voltage characteristics are introduced. These are analyzed with regard to their assumptions and limitations, generalized, and adapted to our use case. A detailed comparison is made to determine the most suitable model. It is found that the choice of model has a large impact, for example, resulting in a change in the inferred temperatures of up to a factor two. This evaluation is implemented in a Bayesian modeling framework and automated to allow for joint analysis with other diagnostics and a replacement of ad hoc assumptions. We rigorously treat parameter uncertainties, revealing strong correlations between them. General and flexible model formulations permit an expansion to additional effects.

    Original languageEnglish
    Article number063505
    JournalReview of Scientific Instruments
    Volume91
    Issue number6
    DOIs
    Publication statusPublished - 1 Jun 2020

    Fingerprint

    Dive into the research topics of 'The Langmuir probe system in the Wendelstein 7-X test divertor'. Together they form a unique fingerprint.

    Cite this