Power exhaust by core radiation at COMPASS tokamak
| Autor: | Olivier Février, Martin Hron, M. Sos, M. Bernert, L. Kripner, Matthias Komm, S. S. Henderson, Martin Imrisek, D. Mancini, D. Naydenkova, M. Morbey, Petra Bilkova, P. Bohm, Radomir Panek, Jordan Cavalier, D. Brida, J. Adamek, Petr Vondracek, M. Jerab |
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| Přispěvatelé: | EUROfusion MST1 Team, Science and Technology of Nuclear Fusion, Applied Physics and Science Education |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Nuclear and High Energy Physics
Materials science Tokamak Thermonuclear fusion Detachment Impurity seeding Neon 7. Clean energy 01 natural sciences 010305 fluids & plasmas law.invention Plasma law Physics::Plasma Physics 0103 physical sciences Argon 010306 general physics Pressure gradient COMPASS tokamak Divertor Mechanics Fusion power Dissipation Condensed Matter Physics Heat flux Nuclear fusion |
| Zdroj: | Nuclear Fusion Nuclear Fusion, 61(3):036016. Institute of Physics |
| ISSN: | 0029-5515 |
| Popis: | Substantial power dissipation in the edge plasma is required for the safe operation of ITER and next-step fusion reactors, otherwise unmitigated heat fluxes at the divertor plasma-facing components (PFCs) would easily exceed their material limits. Traditionally, such heat flux mitigation is linked to the regime of detachment, which is characterised by a significant pressure gradient between upstream and downstream scrape-off layer (SOL). However, the physics phenomena responsible for power dissipation and pressure loss are distinctly different, especially when the power dissipation is achieved by impurity seeding. In principle, it is possible to achieve substantial mitigation of the heat fluxes while maintaining conservation of the pressure along the open field lines in the SOL. This regime can be accessed by injection of medium- or high-Z impurities, which mostly radiate inside the last closed flux surface. The critical question related to such an approach is the effect on confinement and perspective fusion power generation in future thermonuclear reactors. In this work, we report on experiments at COMPASS tokamak, where neon and argon impurities were injected in ohmic or NBI-heated low confinement plasmas. With appropriate seeding waveform, stable scenarios were achieved, avoiding the radiative collapse of plasmas. Significant reduction of heat fluxes at the outer target was observed, with heat flux pattern similar to the one previously achieved by nitrogen seeding. The reduction of downstream pressure was, however, accompanied by an equal reduction of upstream pressure, indicating that the power dissipation occurred inside the separatrix. Indeed, the impurity cooling is causing a significant drop of edge temperature; however, the effect in the plasma centre is much less pronounced. |
| Databáze: | OpenAIRE |
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