Reduction of ELM energy loss by pellet injection for ELM pacing
Reduction of ELM energy loss by pellet injection for ELM pacing
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DOI：
10.1088/0029-5515/53/12/123009
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发表时间：
2013-11
期刊：
影响因子：
3.3
通讯作者：
N. Hayashi;N. Aiba;T. Takizuka;N. Oyama
中科院分区：
文献类型：
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作者：
N. Hayashi;N. Aiba;T. Takizuka;N. Oyama
对于使用 ELMy H 模式等离子体进行 ITER 操作，需要减少由边缘局域模式 (ELM) 引起的能量损失。通过集成核心/刮除层/偏滤器传输代码 TOPICS-IB 以及磁流体动力学稳定性代码和考虑颗粒等离子体云 E × B 漂移的颗粒模型，研究了通过颗粒注射进行 ELM 起搏来减少 ELM 能量损失。研究发现，通过将颗粒注入基座等离子体，可以显着减少能量损失，其能量损失相当于自然ELM周期中间的时间，其压力高度仅比自然ELM开始时低约5%。在这种情况下，从低场侧注入颗粒可以使小颗粒（约占基座颗粒含量的 1-2%）和足够高的速度接近基座顶部，从而显着减少能量损失。在上述适合 ELM 起搏的条件下，颗粒会深入基座并触发高 n 气球模式，在基座顶部附近具有局部特征函数，其中 n 是环形模式数。在合适的条件下，模拟中成功地证明了 ELM 起搏可以减少能量损失，其中气体喷发的减少和偏滤器泵送的增强可以补偿由于起搏颗粒提供额外颗粒燃料而导致的核心密度增加。
The energy loss caused by the edge-localized mode (ELM) needs to be reduced for ITER operations with ELMy H-mode plasmas. The reduction in ELM energy loss by pellet injection for ELM pacing is studied by an integrated core/scrape-off layer/divertor transport code TOPICS-IB with a magnetohydrodynamic stability code and a pellet model taking account of the E × B drift of the pellet plasma cloud. It is found that the energy loss can be significantly reduced by a pellet injected to the pedestal plasma equivalent to that at the middle timing in the natural ELM cycle, whose pressure height is only about 5% lower than that of the natural ELM onset. In this case, pellet injection from the low-field side enables a small pellet, with about 1–2% of pedestal particle content and a speed high enough to approach the pedestal top, to reduce the energy loss significantly. With the above suitable conditions for ELM pacing, a pellet penetrates deep into the pedestal and triggers high-n ballooning modes with localized eigenfunctions near the pedestal top, where n is the toroidal mode number. Under suitable conditions, ELM pacing with reduced energy loss is successfully demonstrated in simulations, in which the gas puff reduction and the enhancement of divertor pumping can compensate for the core density increase due to additional particle fuelling by the pacing pellet.