A dynamical high-pass filter for magnetic fluctuations in full-f field-aligned turbulence codes

IF 7.2 2区物理与天体物理 Q1 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computer Physics Communications Pub Date : 2025-05-15 DOI:10.1016/j.cpc.2025.109670

Kaiyu Zhang, Wladimir Zholobenko, Andreas Stegmeir, Konrad Eder, Frank Jenko

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引用次数: 0

Abstract

Plasma turbulence in the edge of magnetic confinement devices is customarily treated as full-f due to large fluctuations. For computational efficiency, field-aligned coordinates are employed, separating the magnetic field into equilibrium

B_{0}

and delta-f perturbations which are handled by the magnetic flutter operators. Evolving the full-f pressure with delta-f magnetic perturbations can cause inconsistency since the latter contain background components such as the Shafranov shift, which are actually parts of the equilibrium magnetic field. Such background components (

B_{s}

) contained in the magnetic perturbations undermine the field-aligned numerics when treated as flutter: errors arise if

B_{s} / B_{0} ≪ l_{⊥} / h_{∥}

is not satisfied, with the perpendicular turbulence scale

l_{⊥}

and the parallel grid distance

h_{∥}

. We find that the commonly used removal of

B_{s}

by subtracting the toroidal average of magnetic perturbations intervenes in the Alfvén dynamics, causing spurious

E \times B

transport. Instead, we propose an improved method to dynamically filter out the evolving background from the turbulent magnetic fluctuations in the time domain, which is then applicable also for stellarators. The filter is verified in both low and high confinement tokamak conditions, confirming its capability to preserve the turbulence fidelity (provided sufficient filter width).

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一个动态高通滤波器的磁波动在全f场对准湍流代码

由于磁约束装置边缘的等离子体湍流波动较大，因此通常被视为full-f。为提高计算效率，采用场向坐标，将磁场分离为平衡态B0和δ -f微扰，由磁颤振算子处理。用δ -f磁扰动演化全f压力可能导致不一致，因为后者包含背景分量，如沙弗拉诺夫位移，这实际上是平衡磁场的一部分。当被视为颤振时，磁扰动中包含的背景分量（Bs）会破坏场向数值：如果Bs/B0≪l⊥/h∥不满足，垂直的湍流尺度l⊥和平行的栅格距离h∥就会产生误差。我们发现，通过减去磁扰动的环面平均来去除通常使用的Bs干扰了alfv动力学，导致虚假的E×B输运。相反，我们提出了一种改进的方法，从时域的湍流磁波动中动态滤除不断变化的背景，从而也适用于仿星器。该滤波器在低约束和高约束托卡马克条件下进行了验证，确认了其保持湍流保真度的能力（提供足够的滤波器宽度）。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Computer Physics Communications 物理-计算机：跨学科应用

CiteScore

12.10

自引率

3.20%

发文量

287

审稿时长

5.3 months

期刊介绍： The focus of CPC is on contemporary computational methods and techniques and their implementation, the effectiveness of which will normally be evidenced by the author(s) within the context of a substantive problem in physics. Within this setting CPC publishes two types of paper. Computer Programs in Physics (CPiP) These papers describe significant computer programs to be archived in the CPC Program Library which is held in the Mendeley Data repository. The submitted software must be covered by an approved open source licence. Papers and associated computer programs that address a problem of contemporary interest in physics that cannot be solved by current software are particularly encouraged. Computational Physics Papers (CP) These are research papers in, but are not limited to, the following themes across computational physics and related disciplines. mathematical and numerical methods and algorithms; computational models including those associated with the design, control and analysis of experiments; and algebraic computation. Each will normally include software implementation and performance details. The software implementation should, ideally, be available via GitHub, Zenodo or an institutional repository.In addition, research papers on the impact of advanced computer architecture and special purpose computers on computing in the physical sciences and software topics related to, and of importance in, the physical sciences may be considered.