Simulation of plasma current ramp-up with reduced magnetic flux consumption in JT-60SA
Simulation of plasma current ramp-up with reduced magnetic flux consumption in JT-60SA
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JT-60SA 中磁通量消耗减少的等离子体电流斜坡上升仿真
DOI：
10.1088/0741-3335/57/6/065005
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发表时间：
2015
影响因子：
2.2
通讯作者：
and Y. Takase
中科院分区：
文献类型：
--
作者：
T. Wakatsuki;T. Suzuki;N. Hayashi;J. Shiraishi;S. Ide;and Y. Takase
采用湍流模型（CDBM）和集成模拟程序（TOPICS）研究了JT-60 SA中电流上升和中心螺线管（CS）磁通消耗降低的情况。如果等离子体电流被中性束驱动和自举电流过驱动，则等离子体电流可以从0.6 MA斜升到2.1 MA，而没有额外的CS通量消耗。在我们已经检查的情况下，在没有CS通量消耗的情况下电流斜升所需的持续时间长达150 s。为了实现从0.6 MA的电流驱动条件，由较低能量的中性束（85 keV）的电流驱动是有效的。在早期阶段，由于大的透过损失，较高能量的中性束（500 keV）不能在中心电子密度较低（约2× 10 19 m− 3）的情况下使用，而在后期阶段可以有效地使用。因此，主电流驱动器应当在电流斜升阶段期间从较低能量中性束切换到较高能量中性束。作为强烈的辅助加热的结果，等离子体β（等离子体压力与磁压力的比率）变高。用线性理想MHD稳定性分析程序（MARG 2D）研究了这种高β等离子体的理想MHD不稳定性。如果JT-60 SA的稳定板和真空室处有一个完全导电的壁，并且H模基座和内部输运势垒使等离子体具有更宽的压力分布，那么在电流上升过程中，可能影响堆芯等离子体的外部扭结模可以被稳定下来。
Current ramp-up with reduced central solenoid (CS) flux consumption in JT-60SA has been investigated using an integrated modeling code suite (TOPICS) with a turbulent model (CDBM). The plasma current can be ramped-up from 0.6 MA to 2.1 MA with no additional CS flux consumption if the plasma current is overdriven by neutral-beam-driven and bootstrap current. A time duration required for the current ramp-up without CS flux consumption becomes as long as 150 s in the scenario we have examined. In order to achieve a current overdrive condition from 0.6 MA, the current drive by a lower energy neutral beam (85 keV) is effective. A higher energy neutral beam (500 keV) cannot be used in this early phase with a low central electron density (~ 2× 10 19 m− 3) due to large shine through loss, while it can be effectively used in the later phase. Therefore, the main current driver should be switched from the lower energy neutral beam to the higher energy neutral beam during the current ramp-up phase. As a result of an intensive auxiliary heating, plasma beta (the ratio of the plasma pressure to the magnetic pressure) becomes high. Ideal MHD instabilities of such high beta plasmas have been investigated using a linear ideal MHD stability analysis code (MARG2D). External kink modes which might affect the core plasma can be stabilized during the current ramp-up if there is a perfectly conducting wall at the location of the stabilizing plate and the vacuum vessel of JT-60SA and the plasma has a broader pressure profile with the H-mode pedestal and the internal transport barrier.