在用径向局部模拟方法计算新经典输运时,为了保持相空间体积守恒,通常忽略与通量面相切的磁漂移。本文研究了切向磁场漂移对局域新经典输运的影响。为了在新经典输运的局部处理中保留切向磁漂移的影响,发展了一种新的漂移动力学模拟的局部公式。将切向磁漂移引起的相空间体积的可压缩性作为漂移动力学方程的源项,用非哈密顿系统的双权$δf$ Monte Carlo方法[G.~ Hu和J.~ A.~等离子体物理$\rm \textbf{1}$,863(1994)]。结果表明,漂移对托卡马克中新经典输运的影响是可以忽略的。然而,在非轴对称系统中,切向磁漂移实质上改变了新经典输运对径向电场$E_{\rm r}$的依赖性。通过考虑切向磁漂移,消除了传统局域新经典输运模拟中观测到的$E_{\rm r} = 0$周围新经典径向通量的峰值行为。
英文摘要:
In evaluating neoclassical transport by radially-local simulations, the magnetic drift tangential to a flux surface is usually ignored in order to keep the phase-space volume conservation. In this paper, effect of the tangential magnetic drift on the local neoclassical transport are investigated. To retain the effect of the tangential magnetic drift in the local treatment of neoclassical transport, a new local formulation for the drift kinetic simulation is developed. The compressibility of the phase-space volume caused by the tangential magnetic drift is regarded as a source term for the drift kinetic equation, which is solved by using a two-weight $δf$ Monte Carlo method for non-Hamiltonian system [G.~Hu and J.~A.~Krommes, Phys. Plasmas $\rm \textbf{1}$, 863 (1994)]. It is demonstrated that the effect of the drift is negligible for the neoclassical transport in tokamaks. In non-axisymmetric systems, however, the tangential magnetic drift substantially changes the dependence of the neoclassical transport on the radial electric field $E_{\rm r}$. The peaked behavior of the neoclassical radial fluxes around $E_{\rm r} = 0$ observed in conventional local neoclassical transport simulations is removed by taking the tangential magnetic drift into account.
Benchmark of the Local Drift-kinetic Models for Neoclassical Transport Simulation in Helical Plasmas
在此报告了基于几个局部漂移动力学模型的新古典输运程序的基准。这里,漂移动力学模型是ZOW、ZMD、DKES样的和全局的,如在[Matsuoka et al.,Physics of Plasmas 22,072511(2015)]。基准中采用了HSX、LHD和W7-X的磁几何结构。研究发现,当$\boldsymbol E \times \boldsymbol B$与磁漂移速度相比足够大时,$\boldsymbol E \times \boldsymbol B$不可压缩性的假设导致了模型间新经典径向通量和平行流的差异。另一方面,当$\boldsymbol E \times \boldsymbol B$和磁漂移速度是可比的,切向磁漂移,这是包括在全球和ZOW模型,填补了抑制非物理峰值的新古典径向通量在其他本地模型在$E_r \simeq 0$。特别是在低碰撞等离子体中,切向漂移效应很好地抑制了模拟中引起的径向输运的非物理行为。结果表明,ZOW模型具有减轻非物理行为的优势,在几个磁几何形状,它也实现了在LHD的自举电流的计算成本较低的全球模型相比,评估。
Non-linear effects in electron cyclotron current drive applied for the stabilization of neoclassical tearing modes
由于与磁岛的0点周围的通量表面相关联的体积小,在岛内部施加的用于稳定新古典撕裂模式(NTM)的电子回旋功率密度可以超过如先前由Harvey等人,Phys. Rev. Lett. 62(1989)426。我们研究了非线性电子回旋电流驱动(ECCD)的效率,通过反弹平均,准线性福克-普朗克计算的磁几何所创建的岛屿。对ASDEX Upgrade上典型NTM稳定实验的参数进行了计算。这些实验的一个特殊特征是EC波束的射线与功率沉积区域中的通量表面相切地传播。计算结果表明,显着的非线性效应的ECCD效率,当ECCD功率从其实验值的1兆瓦增加到一个更大的值4兆瓦。非线性效应是最大的情况下锁定的岛屿或磁岛旋转周期长于碰撞的时间尺度。对于这种情况,非线性效应导致电流驱动效率的总体降低,其中在电子回旋共振层的低场侧吸收EC功率。由于非线性效应,幼儿保育和发展对该岛的稳定作用也低于线性预期。
Direct, simple, and efficient computation of all components of the virtual-casing magnetic field in axisymmetric geometries with Kapur-Rokhlin quadrature
Turbulent Origin of the Edge Radial Electric Field Asymmetry between Favourable and Unfavourable Drift Configurations
Max-Planck-Institut für Plasmaphysik(马克斯·普朗克等离子体物理研究所);Laboratoire de Physique des Plasmas, CNRS-École Polytechnique(巴黎综合理工学院等离子体物理实验室);École Polytechnique Fédérale de Lausanne (EPFL)(洛桑联邦理工学院)