托卡马克中低动量扩散率区域的物理机制及其实验适用性
Physics of the low momentum diffusivity regime in tokamaks and its experimental applicability
AI总结：
本文通过非线性回旋动理学模拟提出降低动量扩散率以增强流剪切的新方法，发现LMD区域可驱动强流剪切从而显著降低热通量并提高临界温度梯度，并在MAST和SMART托卡马克中验证了其实验适用性。
摘要：
强 $E\ imes B$ 等离子体流剪切有利于减少湍流输运。然而，驱动流剪切的传统方法无法很好地扩展到未来聚变发电厂等大型装置上。在本文中，我们使用大量非线性回旋动理学模拟研究了一种增加流剪切的新方法：降低动量扩散率使等离子体“更容易被推动”。我们首先使用理想化的圆形几何结构，发现在紧凑纵横比、低安全因子、高磁剪切和低温梯度下可以获得低动量扩散率。这就是所谓的低动量扩散率（LMD）区域。为了驱动本征动量通量，我们随后倾斜磁通面，使其上下不对称。在LMD区域中，这种本征动量通量驱动了强流剪切，能够显著降低热通量并提高临界温度梯度。我们还考虑了MAST托卡马克的实际实验几何结构，以说明该策略具有实用性并能产生具有实验意义的流剪切。最后，对SMART托卡马克做出了初步预测。
英文摘要：
Strong $E\times B$ plasma flow shear is beneficial for reducing turbulent transport. However, traditional methods of driving flow shear do not scale well to large devices such as future fusion power plants. In this paper, we use a large number of nonlinear gyrokinetic simulations to study a novel approach to increase flow shear: decreasing the momentum diffusivity to make the plasma ``easier to push''. We first use an idealized circular geometry and find that one can obtain low momentum diffusivity at tight aspect ratio, low safety factor, high magnetic shear and low temperature gradient. This is the so-called Low Momentum Diffusivity (LMD) regime. To drive intrinsic momentum flux, we then tilt the flux surface, making it up-down asymmetric. In the LMD regime, this intrinsic momentum flux drives strong flow shear that can significantly reduce the heat flux and increase the critical temperature gradient. We also consider the actual experimental geometry of the MAST tokamak to illustrate that this strategy can be practical and create experimentally significant flow shear. Lastly, a preliminary prediction for the SMART tokamak is made.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
