One-Dimensional Analysis of ECRH-Assisted Plasma Start-Up in JT-60SA
One-Dimensional Analysis of ECRH-Assisted Plasma Start-Up in JT-60SA
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DOI：
10.13182/fst14-811
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发表时间：
2015-05
影响因子：
0.9
通讯作者：
K. Hada;K. Nagasaki;K. Masuda;S. Kobayashi;S. Ide;A. Isayama;K. Kajiwara
中科院分区：
文献类型：
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作者：
K. Hada;K. Nagasaki;K. Masuda;S. Kobayashi;S. Ide;A. Isayama;K. Kajiwara
摘要利用一维模型分析了二次谐波非常模电子回旋共振加热(ECRH)辅助的等离子体启动。该模型得到了电子和离子的能量输运方程、电子和氢原子的粒子输运方程和环向电流方程。对于圆柱对称的等离子体，也就是直立为具有圆形截面的圆柱体并具有轴向ECRH功率吸收的情形，求解了这些方程。计算表明，在JT-60SA上，ECRH具有启动等离子体的阈值功率。例如，对于初始氢原子密度NH(t=0)=3.0×1018m-3，误差场BERR=1mT，碳和氧杂质分数Nc/Ne=NO/Ne=0.1%，以及EC光束半径约5 cm的等离子体启动，需要大约1 mW的ECRH功率。这一估算的ECRH功率小于计划功率，并且随初始氢原子密度的增加而亚线性增加。阈值功率弱依赖于误差场和碳杂质浓度。对于初始氢原子密度较低的等离子体启动，这一点尤为突出。这一结果表明，抑制误差场和碳杂质密度有助于可靠的等离子体启动。
Abstract By using a one-dimensional model, we analyze plasma start-up assisted by second-harmonic extraordinary-mode electron cyclotron (EC) resonance heating (ECRH). The model leads to energy transport equations for electrons and ions, particle transport equations for electrons and hydrogen atoms, and a toroidal current equation. These equations are solved for a cylindrically symmetrical plasma; that is, a torus straightened to a cylinder with a circular cross section and on-axis ECRH power absorption. The calculation indicates that ECRH has a threshold power for plasma start-up in JT-60SA. For example, approximately 1 MW of ECRH power is required for plasma start-up for an initial hydrogen atom density nH(t=0) = 3.0 × 1018 m-3, an error field Berr = 1 mT, carbon and oxygen impurity fractions nc/ne = no/ne = 0.1%, and an EC beam radius of approximately 5 cm. This estimated ECRH power is less than the planned power and increases sublinearly with the initial hydrogen atom density. The threshold power depends weakly on the error field and carbon impurity concentration. This is especially prominent for plasma start-up with a low initial hydrogen atom density. This result implies that suppressing the error field and carbon impurity density is helpful for reliable plasma start-up.