High heat flux testing of mm thick tungsten coatings on carbon-fiber composites for the JT-60SA tokamak

M. Fukumoto, H. Greuner, B. Böswirth, S. Elgeti, H. Maier, R. Neu, T. Nakano, N. Kuroki, K. Noumi, T. Takabatake, N. Yoshida

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

High heat flux tests have been performed on 0.4 mm thick W coatings produced by vacuum plasma spraying on carbon-fiber composites (CFCs) for the future actively cooled W-coated CFC divertor target in JT-60SA. The surface temperature of the W coating increased up to 2000 °C at 15 MW m−2 for 5 s. No severe morphological changes, for example, melting, cracking and delamination were observed although recrystallization and grain growth were found in the W coating. Cyclic loading at 15 MW m−2 for 3 s with 50 cycles and additional 50 cycles with longer pulse length of 4 s produced again no severe morphological changes. Heat transfer analysis of the W-coated CFC sample during the high heat flux test showed that thermal resistance between W coatings and CFCs was negligibly low. This analysis also showed that the surface temperature of the 1 mm thick W coating on the actively cooled CFC monoblock divertor target in JT-60SA will be higher than the recrystallization temperature, 1200 °C, at the steady state heat flux of 15 MW m−2. Therefore, a reduction of armor thickness of the future actively cooled W-coated CFC monoblock divertor target in JT-60SA could be necessary to decrease the surface temperature to less than the recrystallization temperature.

Original languageEnglish
Article number014029
JournalPhysica Scripta
Volume2017
Issue numberT170
DOIs
StatePublished - 2017

Keywords

  • CFC
  • High heat flux
  • JT-60SA
  • Tungsten
  • Tungsten coating
  • Vacuum plasma spray

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