Status of electron temperature and density measurement with beam emission spectroscopy on thermal helium at TEXTOR

TitleStatus of electron temperature and density measurement with beam emission spectroscopy on thermal helium at TEXTOR
Publication TypeJournal Article
Year of Publication2008
AuthorsO. Schmitz, I.L Beigman, L.A Vainshtein, B. Schweer, M. Kantor, A. Pospieszczyk, Y. Xu, M. Krychowiak, M. Lehnen, U. Samm, B. Unterberg
JournalPlasma Physics and Controlled Fusion
Volume50
Number11
Pagination23
Date PublishedNov
Type of ArticleArticle
ISBN Number0741-3335
Accession NumberISI:000260311700004
KeywordsBOUNDARY, diagnostics, LINE EMISSION, PLASMA EDGE, RADIATIVE MODEL, TRANSPORT
Abstract

Beam emission spectroscopy on thermal helium is used at the TEXTOR tokamak as a reliable method to obtain radial profiles of electron temperature T-e(r, t) and electron density ne(r, t). In this paper the experimental realization of this method at TEXTOR and the status of the atomic physics employed as well as the major factors for the measurement's accuracy are evaluated. On the experimental side, the hardware specifications are described and the impact of the beam atoms on the local plasma parameters is shown to be negligible. On the modeling side the collisional-radiative model (CRM) applied to infer ne and Te from the measured He line intensities is evaluated. The role of proton and deuteron collisions and of charge exchange processes is studied with a new CRM and the impact of these so far neglected processes appears to be of minor importance. Direct comparison to Thomson scattering and fast triple probe data showed that for high densities ne > 3.5 x 10(19) m(-3) the T-e values deduced with the established CRM are too low. However, the new atomic data set implemented in the new CRM leads in general to higher Te values. This allows us to specify the range of reliable application of BES on thermal helium to a range of 2.0 x 10(18)

URL<Go to ISI>://000260311700004
Division

Fusion Physics

PID

191071e2cc5afcad002981af63fdb1d0

Alternate TitlePlasma Phys. Control. Fusion

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