On the origin of the DIII-D L-H power threshold isotope effect
| Autor: | K.J. Callahan, L. Schmitz, T.A. Carter, E.A. Belli, C. Chrystal, S.R. Haskey, B.A. Grierson, K.E. Thome, S.P. Smith, G.R. McKee, G.M. Staebler, C. Holland, A. Ashourvan, Z. Yan |
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| Jazyk: | angličtina |
| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | Nuclear Fusion, Vol 63, Iss 12, p 126009 (2023) |
| Druh dokumentu: | article |
| ISSN: | 1741-4326 0029-5515 |
| DOI: | 10.1088/1741-4326/acf86c |
| Popis: | The increased low to high confinement mode (L to H-mode) power threshold $P_\mathrm{LH}$ in DIII-D low collisionality hydrogen plasmas (compared to deuterium) is shown to result from lower impurity (carbon) content, consistent with reduced (mass-dependent) physical and chemical sputtering of graphite. Trapped gyro-Landau fluid (TGLF) quasilinear calculations and local non-linear gyrokinetic CGYRO simulations confirm stabilization of ion temperature gradient (ITG) driven turbulence by increased carbon ion dilution as the most important isotope effect. In the plasma edge, electron non-adiabaticity is also predicted to contribute to the isotope dependence of thermal transport and $P_\mathrm{LH}$ , however its effect is subdominant compared to changes from impurity isotopic behavior. This L-H power threshold reduction with increasing carbon content at low collisionality is in stark contrast to high collisionality results, where additional impurity content appears to increase the power necessary for H-mode access. |
| Databáze: | Directory of Open Access Journals |
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