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Effects of equilibrium radial electric field on ion temperature gradient instability in the scrape-off layer of a field-reversed configuration
Plasma Physics and Controlled Fusion ( IF 2.2 ) Pub Date : 2021-04-30 , DOI: 10.1088/1361-6587/abf403
W H Wang 1 , J Bao 1 , X S Wei 1 , Z Lin 1 , G J Choi 1 , S Dettrick 2 , A Kuley 3 , C Lau 2 , P F Liu 1 , T Tajima 1, 2
Affiliation  

Linear and nonlinear effects of the equilibrium radial electric field on the ion temperature gradient (ITG) instability in the scrape-off layer (SOL) of a field-reversed configuration have been studied using gyrokinetic particle simulations for a single toroidal mode. Linear simulations with adiabatic electrons find that the $E \times B$ flow shear reduces the growth rate and causes a radial tilting of the mode structure on the toroidal plane. Nonlinear simulations find that the $E \times B$ flow shear significantly decreases ITG saturation amplitude and ion heat transport in the SOL by reducing both turbulence intensity and eddy size. The turbulence intensity is determined by fluid eddy rotation, which is the dominant saturation mechanism for the SOL ITG instability with a single toroidal mode number. On the other hand, parallel wave-particle decorrelation is the dominant mechanism for the SOL ITG turbulent transport. A random walk model using the guiding center radial excursion as the characteristic length scale and the eddy turnover time as the characteristic time scale fits very well to the scaling of ion heat conductivity with the $E \times B$ flow shear.



中文翻译:

平衡径向电场对场反转配置的刮除层中离子温度梯度不稳定性的影响

平衡径向电场对场反转配置的刮除层 (SOL) 中离子温度梯度 (ITG) 不稳定性的线性和非线性影响已使用单环形模式的陀螺运动粒子模拟进行了研究。使用绝热电子的线性模拟发现,$E \times B$流动剪切会降低生长速率并导致环形平面上模式结构的径向倾斜。非线性模拟发现$E \times B$通过降低湍流强度和涡流大小,流动剪切显着降低了 SOL 中的 ITG 饱和幅度和离子热传递。湍流强度由流体涡旋决定,这是具有单一环形模数的 SOL ITG 不稳定性的主要饱和机制。另一方面,平行波粒去相关是 SOL ITG 湍流传输的主要机制。以导向中心径向偏移为特征长度尺度,以涡旋周转时间为特征时间尺度的随机游走模型非常适合离子热导率随$E \times B$流动剪切的尺度变化。

更新日期:2021-04-30
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