Simulation study of mixed-impurity seeding with extension of integrated divertor code SONIC
Simulation study of mixed-impurity seeding with extension of integrated divertor code SONIC
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DOI：
10.1088/1361-6587/ab6f9b
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发表时间：
2020-04-01
影响因子：
2.2
通讯作者：
Hayashi，Nobuhiko
中科院分区：
文献类型：
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作者：
Yamoto，Shohei;Hoshino，Kazuo;Hayashi，Nobuhiko
为了获得决定刮离层(SOL)/偏滤器区域中杂质输运可控性的关键物理参数，集成偏滤器程序SONIC被进一步扩展到动力学地处理三种或更多杂质物种。扩展的SONIC程序已经被应用于JT-60SA的稳态高贝塔情景类等离子体作为试验床。我们首先在固定的Ar种子背景等离子体上进行了Ne输运模拟。在Ar和Ne之间，得到了不同的辐射功率分布。Ar辐射在溶胶顶部附近较强，这主要是由于热力俘获的高电荷态Ar离子的线辐射所致。与之相反，Ne辐射在X点附近的高场侧较强，主要是由于Ne的线辐射被D+平行流动的热力和摩擦力的平衡所俘获。作为第二步，我们进行了Ne播种率的参数调查。Ne输运对等离子体的影响是自洽计算的。Ne杂质以固定的Ar喷发率注入到等离子体中。即使是0.02Pam~3 S−1的小Ne籽入率，也会导致Sol和核边缘的Ar辐射功率比只有Ar的情况低。这主要是由于在Ar+Ne引种情况下，向内偏滤器方向有较高的D+平行流动速度。由此产生的摩擦力将Ar杂质输送到内部偏滤器区域。当在模拟中关闭Ne~(7+)的线辐射时，看不到如此高的D~+平行流。这些结果表明，Ne~(7+)的线辐射在高D~+平行流中起着关键作用。结果表明，通过混合掺杂可以控制溶胶中的杂质输运。
Aimed at obtaining key physics that determine the controllability of impurity transport in the scrape-off layer (SOL)/divertor regions, the integrated divertor code SONIC has been further extended to handle three or more impurity species kinetically. The extended SONIC code has been applied to the steady-state high-beta scenario-like plasma of JT-60SA as a testbed. We first performed a Ne transport simulation on the fixed Ar-seeded background plasma. Different radiation power distribution along the magnetic field line was obtained between Ar and Ne. The Ar radiation is strong around the top region of the SOL, which is mainly due to the line radiation of highly charged Ar ions trapped by the thermal force. In contrast, the Ne radiation is strong around the high-field side near the X point, mainly due to the line radiation of Ne 7+ trapped by the balance between the thermal force and the frictional force with D+ parallel flow. We performed a parametric survey of Ne seeding rate as a second step. The effects of Ne transport on the plasma are self-consistently computed. The Ne impurities are injected into the plasma with a fixed puff rate of Ar. Even a small Ne seeding rate of 0.02 Pa m 3 s− 1 results in lower Ar radiation power in the SOL and core edge than in the Ar-only case. This is mainly due to the high D+ parallel flow velocity towards the inner divertor in the Ar+ Ne seeding case. The resultant frictional force transports the Ar impurities towards the inner divertor region. When the line radiation of Ne 7+ is switched off in the simulation, such high D+ parallel flow cannot be seen. These results suggest that the line radiation of Ne 7+ has a key role for the high D+ parallel flow. The results show the possibility of impurity transport control in the SOL by mixed-impurity seeding.