High heat flux test results for a thermal break DEMO divertor target and subsequent design and manufacture development

This paper focuses on the development of the water-cooled divertor target concept known as Thermal Break, which was carried out in two phases. In Phase 1, six small scale mock-ups were fabricated and subjected to high heat flux (HHF) testing of up to 25 MW/m2 and thermal cycling of up to 500 cycles...

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Bibliographic Details
Published in:Fusion engineering and design 2019-09, Vol.146, p.1657-1660
Main Authors: Lukenskas, Adomas, Barrett, T.R., Fursdon, M., Domptail, F., Schoofs, F., Greuner, H., Dose, G., Roccella, S., Visca, E., Gallay, F., Richou, M., You, J.-H.
Format: Article
Language:English
Subjects:
Brazing
Cracking (fracturing)
CuCrZr
Damage detection
Design optimization
Design parameters
Divertor target
Fracture mechanics
Grooves
Heat flux
Heat transfer
High heat flux
Interlayers
Plastic deformation
Response surface methodology
Thermal barriers
Thermal break
Thermal cycling
Tungsten
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Summary:This paper focuses on the development of the water-cooled divertor target concept known as Thermal Break, which was carried out in two phases. In Phase 1, six small scale mock-ups were fabricated and subjected to high heat flux (HHF) testing of up to 25 MW/m2 and thermal cycling of up to 500 cycles at 20 MW/m2. All six mock-ups survived the campaign and maintained 20 MW/m2 heat exhaust capability. Detailed examination of mock-ups was carried out to understand the damage mechanisms. One mock-up, which was tested beyond its design intent at 500 cycles, shows signs of progressive damage. Potential damage modes were identified and influenced subsequent Phase 2 mock-up design. Although there are signs of tungsten surface cracking, the predominant damage mode is not by “deep cracking” but substantial permanent deformation in the interlayer features. Therefore, in Phase 2 the manufacturing procedure was updated, the interlayer grooves were given stress-relieving radii which have significantly reduced the interlayer plastic strain range. Interlayer design parameters were selected following the use of response surface-based design search and optimization. Mock-ups of the Phase 2 design have been manufactured and HHF testing is planned within 2018.
ISSN:0920-3796
1873-7196
DOI:10.1016/j.fusengdes.2019.03.010