Thermal Radiation Analysis to Calculate the Temperature and
Heat Load of Wendelstein 7-X
Inertially Cooled Test Divertor
Unit Scraper Element
Authors: Han Zhang, Peter Titus, G. Douglas Loesser,
Joris Fellinger
Abstract: The W7-X divertor was designed to
have a maximal allowable heat flux of 5MW/m2.
However, in certain magnetic configurations, high flux footprints
due to the evolution of bootstrap currents results in high heat
loads to the divertor units. Previous study shows the heat load
can be >10MW/m2,
which significantly exceeds the allowable. Thus the scraper
element was designed to protect the sensitive areas of the
divertor and at the same time, not to affect normal
configurations.
A one dimensional radiation analysis was used to evaluate
transient heating and cooling processes of the scraper element. A
three dimensional radiation simulation, with views of cooler
regions of the vessel interior, demonstrates better heat removal
from the components behind the plasma facing tile surface. A three
dimensional ANSYS model has been built that includes the scraper,
its backing and neighboring vessel internals. The Test Divertor
Units (TDU), and wall panels act as thermal shields to protect the
vacuum vessel. View factors are calculated using ANSYS /AUX12. The
advantage of using aux12 is that the view factor matrix may be
calculated once, after that, changing the thermal load just
requires another run. There is no need to calculate the view
factors again. Simulation shows that with 8MW/m2
peak to 0.05m wide area of scraper, 20 minutes for cooling, the
scraper temperature thermal ratcheting is within the 1740K tile
limit and the wall panel temperature within 355K. Heat flux plots
have been provided for other analysis. Temperature results have
been transferred to a structural run. Temperature results for the
scraper and other areas behind the test divertor units are
provided.
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Presented at: IEEE 26th Symposium on Fusion
Engineering, (SOFE), Austin, TX, May 31-June 4, 2015
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Download PPPL-5171
(pdf 6.5 MB 7 pp)
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