Effects of toroidal flows on ballooning mode instabilities have been studied extensively in recent years. In the published works, toroidal flow effects are taken into account only in the perturbation equation while the tokamak equilibrium is assumed to be unchanged. In this work, the influence of a toroidal flow on ballooning mode instabilities is numerically investigated by using the BOUT++ code while the modification of the tokamak equilibrium due to the flow has been taken into account in fixing the profiles of the quasi-toroidal magnetic field, quasi-density, and quasi-pressure and only changing the toroidal Mach number. A toroidal flow can significantly modify the safety factor q profile and the pressure gradient ∇P, which then affects the ballooning instability. The simulation results show that in the presence of shear flows, the growth rate of the ballooning mode will be affected if the modified equilibrium is considered. For a shear flow, the growth rates of high-n modes are significantly reduced.

中文翻译：

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环形平衡流对托卡马克气球模式稳定的影响

近年来，已经广泛研究了环形流动对膨胀模式不稳定性的影响。在已发表的著作中，仅在扰动方程式中考虑了环流效应，而假定托卡马克平衡不变。在这项工作中，通过使用BOUT ++代码对环形流对膨胀模式不稳定性的影响进行了数值研究，同时在确定准环形磁场的分布时已考虑到由于流动导致的托卡马克平衡的修正，准密度和准压力只改变环形马赫数。甲环形流可显著修改的安全系数q轮廓和压力梯度∇ P，从而影响膨胀的不稳定性。仿真结果表明，在存在剪切流的情况下，如果考虑修正的平衡，则将影响膨胀模式的增长率。对于剪切流，高n模式的增长率显着降低。