Identifying the impact of rotation, anisotropy, and energetic particle physics in tokamaks
Identifying the impact of rotation, anisotropy, and energetic particle physics in tokamaks
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DOI：
10.1088/0741-3335/53/7/074021
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发表时间：
2011-05
影响因子：
2.2
通讯作者：
M. Hole;G. V. von Nessi;M. Fitzgerald;K. McClements;J. Svensson
中科院分区：
文献类型：
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作者：
M. Hole;G. V. von Nessi;M. Fitzgerald;K. McClements;J. Svensson
本文研究了托卡马克中极向旋转和环向旋转以及各向异性的影响。为了解决这些数据不确定性的影响，我们引入了一个贝叶斯推理框架，该框架利用运动斯塔克效应和磁数据概率地计算磁组态。利用这些计算，我们计算了具有良好旋转数据的放电在MAST中的极向和环向马赫数。我们的计算证实，极向马赫数Ms，θ = vθ/vi × B/Bθ接近于零（vθ和vi分别为极向和热速度），即使在极向场强Bθ与总场强B的比例较大的舷外侧也是如此。相反，等离子体的环向旋转在轴上达到0.5马赫数。然而，环向旋转对等离子体平衡重建的影响很小：它的作用是使磁轴半径增加约1%，使中心安全系数降低约5%。相比之下，为了使压力剖面与内部测量结果（如电荷交换复合光谱和汤姆逊散射）保持一致而进行的修正影响要大得多。在其他工作中，我们从中性束加热的MAST放电的TRANSP模拟计算了各向异性的水平。这显示了很大程度的各向异性，p⊥/p∥≈1.7，足以将中心安全系数提高15%。对于这种具有代表性的许多MAST放电，各向异性和一致的压力分布的影响比等离子体的环向旋转更为明显。
In this paper we study the effects of poloidal and toroidal rotation, and anisotropy in tokamaks. To resolve these effects from uncertainties in the data, we introduce a Bayesian inference framework which calculates the magnetic configuration probabilistically using motional Stark effect and magnetic data. Drawing on these calculations, we compute the poloidal and toroidal Mach numbers in MAST for a discharge with good rotation data. Our calculations confirm that the poloidal Mach number Ms,θ = vθ/vi × B/Bθ is near zero (with vθ and vi the poloidal and thermal velocity, respectively), even on the outboard side where the scaling of poloidal field strength Bθ to total field B is large. In contrast, the toroidal rotation of this plasma reaches a Mach number of 0.5 on axis. The impact of the toroidal rotation on the equilibrium reconstructions of the plasma is however small: it acts to increase the radius of the magnetic axis by ≈1%, and lower the central safety factor by ≈5%. In comparison, corrections to make the pressure profile consistent with internal measurements such as charge exchange recombination spectroscopy and Thomson scattering have a much larger impact. In other work we compute the level of anisotropy from a TRANSP simulation of a neutral beam-heated MAST discharge. This shows a large level of anisotropy, with p⊥/p∥ ≈ 1.7, sufficient to boost the central safety factor by 15%. For this discharge, which is representative of many MAST discharges, the effect of anisotropy and consistent pressure profiles is more pronounced than the toroidal rotation of the plasma.