The Steady State Challenge for Soft X-Ray Diagnostics on Wendelstein 7-X Stellarator

Journal Article · Wed Mar 19 04:00:00 EDT 2008 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.2909099· OSTI ID:21136897

Thomsen, H; Broszat, T; Mohr, S; Weller, A; Ye, M Y ^[1]; Carvalho, P ^[2]

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1. Max-Planck-Institute fuer Plasmaphysik, Wendelsteinstr. 1, 17491 Greifswald (Germany)
2. Associacao Euratom/IST Centro de Fusao Nuclear, Instituto Superior Tecnico 1049-001 Lisboa (Portugal)

The steady state operation of Wendelstein 7-X stellarator presently under construction in Greifswald poses special challenges to the diagnostics development [1, 2]. A critical issue is the heat load on plasma facing components ({approx}500 kW/m{sup 2}) over a long discharge time (up to 30 min), which leads to the necessity of active cooling. As result, the design of the 400 channel soft X-Ray Multi Camera Tomography System (XMCTS) [2, 3] has to cope with dark currents and amplifier drifts due to the heating of active components like photo diodes and in-vessel preamplifiers. In order to allow for a quantitative measurement of dynamic drifts and offsets, a shutter system and blind diodes are considered to compensate these effects. Another important issue is the large amount of data gathered by the XMCT system during long pulse discharges. A fast but less precise online reconstruction is planned, which will give information on the plasma shape and position on a human time scale. The two options under investigation are a Cormack-Inversion method and an approach based on neural networks [4]. Dependent on the available hardware, as much information as possible should be stored for more accurate offline-analysis. An intelligent way of marking interesting data is required. In case that the steady-state storage of all measured data is not feasible, at least this marked data will be stored in high time resolution.

• OSTI ID: 21136897
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 993; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CAMERAS
COMPUTERIZED TOMOGRAPHY
ELECTRIC DISCHARGES
FIRST WALL
HEATING LOAD
NEURAL NETWORKS
PHOTODIODES
PLASMA
PLASMA DIAGNOSTICS
SOFT X RADIATION
STEADY-STATE CONDITIONS
TIME RESOLUTION
WENDELSTEIN-7 STELLARATOR