Predicting residual stress (RS) contribution to intrinsic rotation is one of the major challenges in the study of momentum transport in tokamaks. One efficient experimental means of quantifying RS torque magnitude is to generate radially-flat and near-zero rotation profiles, termed ‘balanced rotations’ in this work, using counter-I_p Neutral Beam Injections (NBIs) to effectively cancel the torques from co-I_p NBIs. One remaining question, however, is on whether or not the attained velocity profile is well zeroed and flat enough so that the predicted RS torques based on perfect balance assumption can be used for further studies such as fitting of diffusive and convective coefficients to match with experiments. This article presents a neoclassical means of validating the attained balanced and unbalanced rotations at EAST to consequently validate the predicted RS torque profiles, using TRANSP/NUBEAM and a recently-developed neoclassical rotation/transport code TransROTA (Bae et al 2024 Comput. Phys. Commun. 296 108992). Both balanced and unbalanced EAST H-mode discharges are analyzed to find that the suggested neoclassical validation methodology successfully validates attained balanced rotations. It also finds that neoclassical gyroviscous (NGV) torque serves as the balance-breaking mechanism for axisymmetric plasmas and the balance-breakings start from the core and propagate towards the edge. This work also suggests the possibility of using the neoclassical methodology to find locally-balanced rotations at an elevated velocity range near ∼20 km s⁻¹, which implies possible scaling of RS torques up to a certain elevated velocity range.

中文翻译：

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EAST H 模式放电平衡和不平衡旋转的新古典验证

预测残余应力（RS）对内旋转的贡献是托卡马克动量传输研究的主要挑战之一。量化 RS 扭矩大小的一种有效实验方法是生成径向平坦且接近零的旋转轮廓，在本工作中称为“平衡旋转”，使用反我_p 中性束喷射 (NBI) 可有效消除来自 co- 的扭矩我_p NBI。然而，剩下的一个问题是所获得的速度分布是否良好调零且足够平坦，以便基于完美平衡假设的预测 RS 扭矩可用于进一步的研究，例如拟合扩散和对流系数以与实验相匹配。本文提出了一种新古典方法，使用 TRANSP/NUBEAM 和最近开发的新古典旋转/传输代码 TransROTA（Bae等人2024年计算。物理。交流。 296108992）。对平衡和不平衡 EAST H 模式放电进行了分析，发现建议的新古典验证方法成功地验证了所获得的平衡旋转。它还发现新古典回旋粘性（NGV）扭矩充当轴对称等离子体的平衡破坏机制，并且平衡破坏从核心开始并向边缘传播。这项工作还提出了使用新古典方法在接近〜20 km s ^-1的高速范围内找到局部平衡旋转的可能性，这意味着RS扭矩可能缩放到一定的高速范围。