The Steady State Challenge for Soft X-Ray Diagnostics on Wendelstein 7-X Stellarator
- Max-Planck-Institute fuer Plasmaphysik, Wendelsteinstr. 1, 17491 Greifswald (Germany)
- 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, Vol. 993, Issue 1; Conference: PLASMA 2007: International conference on research and applications of plasmas; 4. German-Polish conference on plasma diagnostics for fusion and applications; 6. French-Polish seminar on thermal plasma in space and laboratory, Greifswald (Germany), 16-19 Oct 2007; Other Information: DOI: 10.1063/1.2909099; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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