Transient analysis of high-Z impurity screening by additional injection of low-Z impurity using integrated divertor code SONIC

Autor: Shohei Yamoto, Kazuo Hoshino, Yuki Homma, Tomohide Nakano, Nobuhiko Hayashi
Jazyk: angličtina
Rok vydání: 2023
Předmět:
Zdroj: Nuclear Fusion, Vol 63, Iss 7, p 076019 (2023)
Druh dokumentu: article
ISSN: 1741-4326
0029-5515
10849548
DOI: 10.1088/1741-4326/acd12c
Popis: The dynamics of the screening effect of Ar impurity by the injection of additional Ne has been studied through time-dependent analysis with the integrated divertor code SONIC. In the preceding study (Yamoto et al 2020 Plasma Phys. Control. Fusion 62 045006), the predictive simulation of JT-60SA plasma by SONIC has shown that the injection of additional Ne into Ar-seeded plasma results in lower Ar density and radiation power in the SOL and core edge than in the Ar-only seeded case. The results have demonstrated that the mixed impurity seeding of Ar and Ne may be advantageous for maintaining a high core plasma performance with a low divertor heat load. It was found that the friction force induced by the high D ^+ flow in the SOL towards the inner divertor (ID) region in the Ar + Ne seeded case pushes Ar impurities to the ID. However, the dynamics of D ^+ flow acceleration cannot be interpreted in the previous study because SONIC was a steady state code. In this study, we have developed the time-dependent version of SONIC and applied it to the transient analysis of the injection of additional Ne into Ar-seeded plasma in JT-60SA. When additional Ne is injected, Ne ions stay in the ID plasma near the X-point. As a result, the Ne radiation power increases near the X-point. The electron pressure then decreases due to the radiation cooling and the D ^+ flow is accelerated by the electron pressure gradient. The ion pressure also decreases due to the convection by the accelerated D ^+ flow by electron pressure gradient. The resulting ion pressure gradient further accelerates the D ^+ flow velocity towards the ID. The results suggest that both the high-performance core plasma and the low divertor heat load can be achieved by the Ar + Ne mixed impurity seeding.
Databáze: Directory of Open Access Journals
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