Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges
Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges
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DOI：
10.1088/1741-4326/aa6cd3
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发表时间：
2017-05
期刊：
影响因子：
3.3
通讯作者：
R. Lunsford;A. Bortolon;A. Roquemore;D. Mansfield;M. Jaworski;R. Kaita;R. Maingi;A. Nagy
中科院分区：
文献类型：
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作者：
R. Lunsford;A. Bortolon;A. Roquemore;D. Mansfield;M. Jaworski;R. Kaita;R. Maingi;A. Nagy
通过采用中性气体屏蔽（NGS）模型来表征杂质颗粒注入，三种不同种类的颗粒：锂，硼，和碳，的烧蚀率进行了测定。利用在DIII-D进行的实验中记录的消融事件的持续时间来校准NGS模型，我们量化了消融率相对于等离子体密度分布。然后使用特定种类的颗粒屏蔽常数来模拟NSTX-U放电内的颗粒消融。对NSTX-U L模式等离子体以及自然ELM频率较低的H模式放电，以50 m s-1注入直径为300、500和700 μ m的颗粒进行了模拟。此外，每种物质的500微米颗粒的烧蚀计算在速度范围从50-150 m s-1。在H-模式放电这些模拟表明，大多数注入的颗粒烧蚀内或刚刚过去的边缘陡梯度区域。在这个径向位置，由烧蚀颗粒产生的背景等离子体的扰动可以导致有利于快速触发ELM崩溃的条件。
By employing a neutral gas shielding (NGS) model to characterize impurity granule injection, the ablation rates for three different species of granule: lithium, boron, and carbon, are determined. Utilizing the duration of ablation events recorded on experiments performed at DIII-D to calibrate the NGS model, we quantify the ablation rate with respect to the plasma density profile. The species-specific granule shielding constant is then used to model granule ablation within NSTX-U discharges. Simulations of 300, 500 and 700 micron diameter granules injected at 50 m s−1 are presented for NSTX-U L-mode type plasmas, as well as H-mode discharges with low natural ELM frequency. Additionally, ablation calculations of 500 micron granules of each species are presented at velocities ranging from 50–150 m s−1. In H-mode discharges these simulations show that the majority of the injected granule is ablated within or just past the edge steep gradient region. At this radial position, the perturbation to the background plasma generated by the ablating granule can lead to conditions advantageous for the rapid triggering of ELM crashes.