Flush-mounted Langmuir probes in the WEST tokamak divertor

0552287 - ÚFP 2022 RIV CH eng J - Journal Article
Dejarnac, Renaud - Šesták, David - Gunn, J. P. - Firdaouss, M. - Greuner, H. - Pascal, J. Y. - Richou, M. - Roche, H.
Flush-mounted Langmuir probes in the WEST tokamak divertor.
Fusion Engineering and Design. Roč. 163, February (2021), č. článku 112120. ISSN 0920-3796. E-ISSN 1873-7196
R&D Projects: GA MŠMT(CZ) EF16_019/0000768; GA MŠMT(CZ) LM2018117
Institutional support: RVO:61389021
Keywords : Divertor * Flush-mounted * Langmuir probes * Tantalum * Tokamak * west
OECD category: Fluids and plasma physics (including surface physics)
Impact factor: 1.905, year: 2021
Method of publishing: Limited access
https://www.sciencedirect.com/science/article/pii/S0920379620306682?via%3Dihub

The design of the Langmuir probes for the lower divertor of the WEST tokamak is presented, in which uncooled, tungsten-coated graphite targets were installed for the first phase of operation in anticipation of full-tungsten, actively cooled, ITER-like divertor components. Due to the long plasma discharges and high heat loads, the probe tips are flush with the divertor tiles in which they are embedded, as it is foreseen and indeed required in ITER. Tantalum metal was chosen for the probe tips because of its high melting point, and ductility at room temperature which allows simple crimping to electrically connect them to cables, as well as being compatible with the full metal environment of WEST. High heat flux tests of Ta Langmuir probe prototypes confirmed the robustness of the design for energy flux densities up to 8 MW/m2 for 5.5 s, and at lower 3.5 MW/m² energy flux density for 40 s long discharges. The probes were operational from the first discharge in WEST and the good alignment of all probes with the surrounding surface was confirmed by a good match of each adjacent probe's data when the strike points were swept across the target.
Permanent Link: http://hdl.handle.net/11104/0327416