Title: Determination of 2D poloidal maps of the intrinsic W density for transport studies in JET-ILW

Abstract

The experimental method developed at ASDEX Upgrade for the determination of the intrinsic tungsten (W) density profile coupling data from the soft X-ray (SXR) diagnostic and vacuum-ultra-violet (VUV) spectroscopy has been upgraded for application to JET plasmas. The strong poloidal asymmetries in the SXR emission are modeled assuming a ln $\ln \left(ϵ\left(\rho ,R\right)/ϵ\left(\rho ,R_0\right)\right)=\lambda \left(\rho \right)\left(R^2-R_0^2\right)$ distribution, where ρ is the flux coordinate, R is the major radius, and λ is the fit parameter. The W density is calculated from the resulting 2D SXR emissivity maps accounting for contributions from a low-Z impurity (typically beryllium) and main ion with the assumption that their contributions are poloidally symmetric. Comparing the result with the independent W concentration measurement of VUV spectroscopy, a recalibration factor for the SXR emissivity is calculated making the method robust against the decrease in the sensitivity of the SXR diodes which has been observed across multiple campaigns. The final 2D W density map is checked for consistency versus the time-evolution of the W concentration measurement from VUV spectroscopy, toroidal rotation measurements from charge exchange recombination spectroscopy, and tomographic reconstructions of bolometry data. The method has been found to be robust for W concentrations above a few 10^-5 and in cases where the contributions from other medium-Z impurities such as Ni are negligible.

Authors:

Sertoli, Marco  ^[1];

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Flanagan, Joanne ^[2]; Maslov, Mikhail ^[2]; Maggi, Costanza ^[2]; Coffey, Ivor ^[2]; Giroud, Carine ^[2]; Menmuir, Sheena ^[2]; Carvalho, Pedro ^[3]; Shaw, Anthony ^[2]; Delabie, Ephrem ^[4]

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+ Show Author Affiliations

1. Max Planck Institut für Plasmaphysik, Garching (Germany); Culham Science Centre, Abingdon (United Kingdom). Culham Centre for Fusion Energy (CCFE), EURATOM/UKAEA Fusion Association
2. Culham Science Centre, Abingdon (United Kingdom). Culham Centre for Fusion Energy (CCFE), EURATOM/UKAEA Fusion Association
3. Universidade de Lisboa (Portugal)
4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:

Thu Nov 01 00:00:00 EDT 2018

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1811412

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Review of Scientific Instruments

Additional Journal Information:

Journal Volume: 89; Journal Issue: 11; Journal ID: ISSN 0034-6748

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

47 OTHER INSTRUMENTATION; Rotation measurement; Tokamaks; Impurity levels; X-rays; VUV spectroscopy; Electromagnetic radiation detectors; Transport properties