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等离子体物理

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显示 2025年07月08日, 星期二 新的列表

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[1] arXiv:2507.03084 [中文pdf, pdf, html, 其他]
标题: 带电粒子通量不稳定性研究:使用ALPS解析规则化Kappa分布的斯特拉尔电子
标题: Heat-flux Instabilities of Regularized Kappa Distributed Strahl Electrons Resolved with ALPS
Dustin L. Schröder, Marian Lazar, Rodrigo A. López, Horst Fichtner
评论: 14页,13图,1表
期刊参考: 天体物理学杂志,987:110,2025年7月10日
主题: 等离子体物理 (physics.plasm-ph) ; 太阳与恒星天体物理学 (astro-ph.SR) ; 空间物理 (physics.space-ph)

太阳风的流体行为受到超热电子种群携带的热通量的影响,特别是沿磁场传播的电子束(或射线)。 相反,电子束不能保持稳定,在没有碰撞的情况下,其特性主要由自生成的不稳定性调节。 本文使用正则化Kappa分布(RKDs)以一种新的方式描述这些热通量不稳定性,以表征电子束。 RKDs符合在原位观测到的具有超热尾部的速度分布,同时允许基于其无奇点矩的一致宏观建模。 相比之下,RKD模型的复杂性使得解析动力学形式变得复杂且仍不可行,因此,这里使用先进的求解器ALPS来解决热通量不稳定性。 根据等离子体条件,两种主要类型的不稳定性出现:哨声波和火 hose 热通量不稳定性。 通过与标准分布(如麦克斯韦分布和Kappa分布)的先前结果进行比较,首次成功测试了该求解器。 此外,新的RKD结果表明,理想化的麦克斯韦模型可能会高估或低估这些不稳定性的影响,并且与标准Kappa得到的结果有所不同,例如,标准Kappa会低估火 hose 热通量增长速率。

The fluid behavior of the solar wind is affected by the heat flux carried by the suprathermal electron populations, especially the electron strahl (or beam) that propagates along the magnetic field. In turn, the electron strahl cannot be stable, and in the absence of collisions, its properties are regulated mainly by self-generated instabilities. This paper approaches the description of these heat-flux instabilities in a novel manner using regularized Kappa distributions (RKDs) to characterize the electron strahl. RKDs conform to the velocity distributions with suprathermal tails observed in situ, and at the same time allow for consistent macromodeling, based on their singularity-free moments. In contrast, the complexity of RKD models makes the analytical kinetic formalism complicated and still inaccessible, and therefore, here heat-flux instabilities are resolved using the advanced solver ALPS. Two primary types of instabilities emerge depending on plasma conditions: the whistler and firehose heat-flux instabilities. The solver is successfully tested for the first time for such instabilities by comparison with previous results for standard distributions, such as Maxwellian and Kappa. Moreover, the new RKD results show that idealized Maxwellian models can overrate or underestimate the effects of these instabilities, and also show differences from those obtained for the standard Kappa, which, for instance, underestimate the firehose heat-flux growth rates.

[2] arXiv:2507.03179 [中文pdf, pdf, html, 其他]
标题: 利用等离子体尾波场加速器对水中激光驱动冲击的多信使动态成像
标题: Multi-messenger dynamic imaging of laser-driven shocks in water using a plasma wakefield accelerator
Mario D. Balcazar, Hai-En Tsai, Tobias Ostermayr, Paul T. Campbell, Qiang Chen, Cary Colgan, Gillis M. Dyer, Zachary Eisentraut, Eric Esarey, Cameron G. R. Geddes, Benjamin Greenwood, Anthony Gonsalves, Sahel Hakimi, Robert Jacob, Brendan Kettle, Paul King, Karl Krushelnick, Nuno Lemos, Eva Los, Yong Ma, Stuart P. D. Mangles, John Nees, Isabella M. Pagano, Carl Schroeder, Raspberry Simpson, Alexander G. R. Thomas, Matthew Trantham, Jeroen van Tilborg, Anthony Vazquez, Carolyn C. Kuranz
评论: 34页,共12张图(主文章中6张,扩展数据中6张)
主题: 等离子体物理 (physics.plasm-ph) ; 高能物理 - 实验 (hep-ex)

理解致密物质流体动力学对于预测激光驱动惯性约束聚变相关环境中的等离子体行为至关重要。 传统的诊断光源在亮度、时空分辨率以及无法检测相关电磁场方面存在局限性。 在本工作中,我们展示了一个双探针、多信使激光尾波加速平台,在1赫兹频率下结合超快X射线和相对论电子束,以探测真空中的自由流动水靶,该靶由一个强烈的200皮秒激光脉冲加热。 该方案利用两种粒子类型实现了高重复率的相互作用演化跟踪。 贝特atron X射线揭示了一种由低密度蒸汽辅助的圆柱对称冲击压缩形态,类似于泡沫层辅助的聚变靶。 同步电子束检测随时间演化的电磁场,揭示了等离子体膨胀过程中的电荷分离和离子种类分化现象——这些现象未被光子或流体动力学模拟捕捉到。 我们表明,结合两种探针提供了跨越动力学到流体动力学区域的互补见解,突显了需要混合物理模型来准确预测聚变相关的等离子体行为。

Understanding dense matter hydrodynamics is critical for predicting plasma behavior in environments relevant to laser-driven inertial confinement fusion. Traditional diagnostic sources face limitations in brightness, spatiotemporal resolution, and inability to detect relevant electromagnetic fields. In this work, we present a dual-probe, multi-messenger laser wakefield accelerator platform combining ultrafast X-rays and relativistic electron beams at 1 Hz, to interrogate a free-flowing water target in vacuum, heated by an intense 200 ps laser pulse. This scheme enables high-repetition-rate tracking of the interaction evolution using both particle types. Betatron X-rays reveal a cylindrically symmetric shock compression morphology assisted by low-density vapor, resembling foam-layer-assisted fusion targets. The synchronized electron beam detects time-evolving electromagnetic fields, uncovering charge separation and ion species differentiation during plasma expansion - phenomena not captured by photons or hydrodynamic simulations. We show that combining both probes provides complementary insights spanning kinetic to hydrodynamic regimes, highlighting the need for hybrid physics models to accurately predict fusion-relevant plasma behavior

[3] arXiv:2507.03396 [中文pdf, pdf, 其他]
标题: 高压频率对空气常压气体放电中RONS物种密度的影响数值研究
标题: Numerical investigation of the effect of high voltage frequency on the density of RONS species in the air atmospheric pressure gas discharge
Fariborz Momtazzadeh, Farshad Sohbatzadeh, Hamed Soltani Ahmadi, Ramin Mehrabifard
主题: 等离子体物理 (physics.plasm-ph)

在过去几十年中,等离子体技术各个领域的研究不断扩展,其在不同过程中的应用也有所增加。因此,获得具有特定特性的理想且实用的等离子体尤为重要。施加的电压频率是影响物理和化学特性的重要因素之一。在本研究中,从500 Hz到500 kHz的频率范围内,通过施加2 kV的恒定电压,研究了使用介质阻挡和空气工作气体产生的活性物种密度的变化。为此,在COMSOL Multiphysics中定义了87种具有特定碰撞截面的反应。其他参数,包括电流-电压波形、电场和物种密度也被评估。结果表明,在完全相同的条件下,随着施加频率的增加,电子温度分布发生变化,而活性氧和氮物种RONS的密度降低,但O表现出增加的趋势。需要注意的是,模拟结果与之前的实验和模拟报告有很好的一致性。这些结果为优化不同应用的等离子体参数提供了有价值的见解,可能在多个治疗领域带来更好的治疗效果。

In the last few decades, studies in various fields of plasma technology have expanded and its application in different processes has increased. Therefore, the achievement of a desirable and practical plasma with specific characteristics is of particular importance. The frequency of the applied voltage is one of the important factors that play a role in the physical and chemical characteristics. In this research, changes in the density of active species produced in an electrical discharge using a dielectric barrier and air working gas have been investigated from a frequency of 500 Hz to 500 kHz, and by applying a constant voltage of 2 kV, have been investigated. For this purpose, 87 different reactions with specific collision cross-sections were defined in COMSOL Multiphysics. Other parameters, including current-voltage waveform, electric field, and species densitywere evaluated. The results show that under completely identical conditions, the electron temperature distribution changes with increasing applied frequency, and the density of reactive oxygen and nitrogen species RONS decreases, but O shows an increasing trend. It should be noted that the simulation results are in good agreement with previous experimental and simulation reports. These results offer valuable insights into optimizing plasma parameters for different applications, potentially resulting in better treatment outcomes across a range of therapeutic domains.

[4] arXiv:2507.03645 [中文pdf, pdf, html, 其他]
标题: 非线性波混合在 Yukawa 一成分等离子体中
标题: Nonlinear Mixing of Waves in a Yukawa One Component Plasma
Ajaz Mir, Farida Batool, Sanat Tiwari, Abhijit Sen
主题: 等离子体物理 (physics.plasm-ph)

非线性波混频现象在使用二维经典朗之万分子动力学模拟的Yukawa单组分等离子体中进行了研究。 波谱表明,激发模态之间的非线性相互作用主要由三波混频机制控制,这通过双谱分析得到了证实。 特别是模拟中观察到的混频特性与之前对受迫Korteweg-de Vries(fKdV)模型的数值研究[Phys. Plasmas 29, 032303 (2022)]中报告的特性非常相似。 这种相似性进一步验证了fKdV流体模型在合理精度下捕捉带尘埃等离子体弱非线性动力学的适用性。

The phenomenon of nonlinear wave mixing is investigated in a Yukawa one-component plasma using two-dimensional classical Langevin molecular dynamics simulations. The wave spectrum indicates that nonlinear interactions between the excited modes are primarily governed by a three-wave mixing mechanism, as confirmed by bispectral analysis. In particular, the mixing characteristics observed in the simulations closely resemble those reported in previous numerical studies of the forced Korteweg-de Vries (fKdV) model [ Phys. Plasmas 29, 032303 (2022)]. This similarity further validates the applicability of the fKdV fluid model in capturing the weakly nonlinear dynamics of dusty plasmas with reasonable accuracy.

[5] arXiv:2507.03776 [中文pdf, pdf, html, 其他]
标题: 数据驱动方法模拟磁约束聚变装置中磁几何的影响
标题: Data-Driven Approach to Model the Influence of Magnetic Geometry in the Confinement of Fusion Devices
R. Laia, R. Jorge, G. Abreu
主题: 等离子体物理 (physics.plasm-ph)

融合能源装置的设计涉及在竞争性性能指标之间取得平衡,以实现能量增益。 在仿星器中,几何结构非常灵活,并涉及大量自由参数。 这些参数可以优化以实现良好的性能。 主要优化目标之一是全向性,即来自聚变反应的α粒子的约束。 在本研究中,研究了两类全向性仿星器,即准对称和准等时性仿星器。 目的是确定几何结构对全向性的影响,这有助于更深入地了解仿星器的设计空间。 为此,创建并分析了一个仿星器配置数据库,使用监督自编码器框架进行相关性、成对分布和降维分析。 然后,基于该数据库训练一个分类模型,以预测数值求解器的收敛性。 最后,训练两个回归模型,LightGBM及其概率版本LightGBM LSS,以及一个前馈神经网络,以预测准对称性和准等时性,并找出最影响全向性的设计参数。

The design of fusion energy devices involves a balance between competing performance metrics to achieve an energy gain. In stellarators, the geometry is very flexible and involves a large number of free parameters. These can be optimized to achieve good performance. One of the main optimization targets is omnigenity, that is, the confinement of alpha particles stemming from the fusion reactions. In this work, two classes of omnigenous stellarators are studied, namely quasisymmetric and quasi-isodynamic stellarators. The goal is to determine the influence of the geometry on omnigenity, which can lead to greater insight into the design space of stellarators. For this purpose, a database of stellarator configurations is created and analyzed for correlations, pair-wise distributions, and dimensionality reduction using a supervised autoencoder framework. Then, a classification model is trained on this database to predict the convergence of numerical solvers. Finally, two regression models, LightGBM and its probabilistic version, LightGBM LSS, as well as a feed-forward neural network, are trained to predict quasisymmetry and quasi-isodynamiticity and find the design parameters that most influence omnigenity.

[6] arXiv:2507.04301 [中文pdf, pdf, html, 其他]
标题: 激光在$e^{-}$-$μ^{-}$-离子等离子体中的放大
标题: Laser Amplification in $e^{-}$-$μ^{-}$-ion Plasmas
Y. Chen, R. Ou, H. Wang, S. J. Chen, Y. X. Zhong, Y. G. Chen, S. Tan, Y. X. Li, C. Y. Zheng, Z. J. Liu, L. H. Cao, M. M. Zhang, D. P. Feng, W. J. Zuo, C. Z. Xiao
评论: 7页,5图
主题: 等离子体物理 (physics.plasm-ph)

我们研究$e^{-}$-$\mu^{-}$-离子等离子体中的激光放大,其中负缪子部分取代了电子。 理论结果揭示了一种混合等离子体波,称为$\mu$-波,在长波长区域表现出离子声学行为,在短波长区域表现出朗缪尔波类似的行为。 此外,$\mu$-波的兰道阻尼小于朗缪尔波的兰道阻尼。 粒子-网格模拟证实了$e^{-}$-$\mu^{-}$-离子等离子体中不稳定性理论结果。 $\mu$-波通过增强朗缪尔波的兰道阻尼来抑制泵浦驱动的自发不稳定性,从而实现高效的激光放大。 与拉曼放大相比,$\mu$-波放大可以保持种子激光的高斯波形,避免脉冲分裂。 与强耦合布里渊放大相比,$\mu$-波放大表现出较弱的丝状不稳定性。 我们的理论模型可以推广到包含两种带负电粒子的等离子体系统,例如双温度电子等离子体和负离子等离子体。 这些发现确立了$e^{-}$-$\mu^{-}$-离子等离子体作为一种有前途的先进激光放大方案介质。

We investigate laser amplification in $e^{-}$-$\mu^{-}$-ion plasmas, where negative muons partially replace electrons. Theoretical results reveal a hybrid plasma wave, called $\mu$-wave that exhibits ion-acoustic behavior in long-wavelength regime and Langmuir-like behavior in short-wavelength regime. Besides, the Landau damping of $\mu$-wave is smaller than that of Langmuir wave. Particle-in-cell (PIC) simulations confirm the theoretical results of instabilities in$e^{-}$-$\mu^{-}$-ion plasmas. The $\mu$-wave enables efficient laser amplification by suppressing pump-driven spontaneous instabilities through enhanced Landau damping of Langmuir waves. Compared to Raman amplification, $\mu$-wave amplification can maintain the Gaussian waveform of the seed laser, avoiding pulse splitting. Compared to strongcoupling Brillouin amplification, $\mu$-wave amplification exhibits weaker filamentation instability. Our theoretical model can be generalized to other plasma systems containing two species of negatively charged particles, such as two-temperature electron plasmas and negative-ion plasma. These findings establish $e^{-}$-$\mu^{-}$-ion plasma as a promising medium for advanced laser amplification schemes.

[7] arXiv:2507.04336 [中文pdf, pdf, html, 其他]
标题: 从丝状到分层:剪刀形相对论性束等离子体系统中的不稳定性动力学
标题: From Filamentation to Stratification: Instability Dynamics in Scissors-Shaped Relativistic Beam-Plasma System
Xu Liu, Dong Wu, Jie Zhang
主题: 等离子体物理 (physics.plasm-ph)

反流系统是束等离子体不稳定性,如丝状不稳定性的一个典型模型,在高能量密度物理中至关重要。 然而,涉及相交高速电子束的情景会破坏此类系统的固有圆柱对称性。 在这里,我们引入了剪刀形配置,这是一种基本的多速度分量系统,能够捕捉这种对称性的破坏。 通过理论分析和粒子-网格模拟,我们揭示了不稳定性动力学的显著变化:系统经历了分层模式而不是丝状结构。 这种模式被磁重联迅速抑制,导致一个准稳定状态,其磁能比反流情况低两个数量级。 这一发现建立了一种通过几何配置实现被动不稳定性控制的新原理,为天体物理学和惯性约束聚变中的束等离子体相互作用提供了新的视角。 这些基本物理现象可在即将进行的多激光实验中得到验证。

Counter-streaming systems are a canonical model for beam-plasma instabilities, such as the filamentation instability, which is critical in high energy density physics. However, scenarios involving intersecting fast electron beams break the cylindrical symmetry inherent to such systems. Here, we introduce the scissors-shaped configuration, a fundamental multi-velocity-component system that captures this broken symmetry. Through theoretical analysis and particle-in-cell simulations, we reveal a dramatic shift in the instability dynamics: the system undergoes a stratification mode instead of filamentation. This mode is rapidly quenched by magnetic reconnection, leading to a quasi-stable state with magnetic energy two orders of magnitude lower than in the counter-streaming case. This discovery establishes a new principle of passive instability control via geometric configuration, offering a new perspective on beam-plasma interactions in astrophysics and inertial confinement fusion. The underlying physics is verifiable in upcoming multi-laser experiments.

[8] arXiv:2507.04498 [中文pdf, pdf, 其他]
标题: 电流驱动的朗缪尔波流体方法与类型III辐射和哨声波的关系:对PSP和其他太阳风观测的相关性
标题: Fluid approach of current-driven Langmuir waves associated with type III radiation and whistler waves: Relevance to PSP and other solar wind observations
Konrad Sauer, Kaijun Liu
评论: 27页,15图
主题: 等离子体物理 (physics.plasm-ph) ; 太阳与恒星天体物理学 (astro-ph.SR)

基于流体-Maxwell方程的电子-离子等离子体理论模型被提出,该模型描述了由电流驱动的朗缪尔波转化为III型辐射的过程,同时可能激发哨声波。 与Ginzburg和Zhelezniakov(1958)的经典方法不同,该方法不需要任何不稳定性或波的合并,即可将束激发的朗缪尔波在两步过程中转化为电磁辐射。 相反,电子等离子体频率处的电场振荡可以通过不同的驱动电流实现,例如,在核心-束等离子体中t=0时刻的未补偿束流,或者可能代表空间中不同情况的给定电流变化,如激波、磁场回折等。使用线性化方程组来描述朗缪尔波(主要为静电波)与相邻的左旋极化(L)电磁波之间斜向传播时出现的模式耦合。 流体模型的简单性使得可以轻松改变电流剖面参数,从而模拟各种可能的实验条件。 在各种太阳风卫星上对朗缪尔波、III型辐射和哨声波的测量,特别是帕克太阳探测器的一些最新结果,均在所提出的理论模型的背景下进行解释。 对于未补偿的束流情况,流体方法得到了全动能PIC模拟的验证。 附录中展示了一个比较。

A theoretical model on the basis of fluid-Maxwell equations for an electron-ion plasma is presented which describes the conversion of current-driven Langmuir waves into type III radiation whereby simultaneously an excitation of whistler waves may occur. In contrast to the classical approach of Ginzburg and Zhelezniakov (1958) after which beam-excited Langmuir waves in a two-step process are converted in electromagnetic radiation, the presented mechanism works without any instability and wave coalescence. Rather the electric field oscillations at the electron plasma frequency can be triggered by different realisations of the driving current, e.g. by the (uncompensated) net current of the strahl at t=0 in a core-strahl plasma or by given current variations which may represent different situations in space, as shocks, magnetic switch-backs etc.. A linearized system of equations is used to describe the mode coupling occurring at oblique propagation between the mostly electrostatic Langmuir wave and the adjacent electromagnetic left-hand polarized (L) wave. The simplicity of the fluid model allows without great effort the parameters of the current profiles to be varied and thus to simulate a wide range of possible experimental conditions. Measurements of Langmuir waves, type III radiation and whistler waves on board various satellites in the solar wind, and in particular some of the recent results of the Parker Solar Probe are interpreted in the light of the theoretical model presented. For the case of the uncompensated strahl, the fluid approach is confirmed by fully kinetic PIC simulations. One comparison is shown in the Appendix.

[9] arXiv:2507.04506 [中文pdf, pdf, 其他]
标题: PIC模拟电子核心-束流等离子体中电流驱动的太阳III型辐射和哨声波:与PSP及其他空间观测的相关性
标题: PIC simulation of current-driven solar type III radiation and whistler waves in an electron core-strahl plasma: Relevance to PSP and other space observations
Konrad Sauer, Kaijun Liu
评论: 18页,13图
主题: 等离子体物理 (physics.plasm-ph) ; 太阳与恒星天体物理学 (astro-ph.SR)

本文的目的是证明电子电流振荡可能通过波的合并产生类型III辐射和哨音波,而无需通过经典等离子体发射。 展示了没有初始电流补偿的电子核心-束流等离子体的PIC模拟结果,这些结果描述了由电流驱动的朗缪尔振荡/波转化为类型III辐射,同时激发哨音波。 与Ginzburg和Zhelezniakov(1958)的经典方法不同,该方法中通过两步过程将束流激发的朗缪尔波转换为电磁辐射,通过选择低的束流速度来抑制任何不稳定性。 相反,由最初未补偿的束流电流触发了电子等离子体频率的电场振荡。 产生的电磁场表现出振幅振荡,这是由于混合极化两种波模式在模式耦合点的叠加引起的。 这种基本的波生成和转换机制已经在早期论文中使用简单的流体模型进行了描述。 这也是配套论文的主题。 除了基本的电磁辐射外,还获得了几乎相同强度的二次谐波,这表明存在非线性电流。 在我们的结果背景下,分析了各种卫星上测量的朗缪尔波、类型III辐射和哨音波,特别是帕克太阳探测器(PSP)的观测结果。 对早期的PIC模拟结果进行了批判性回顾。

The aim of the paper is to demonstrate that electron current oscillations may generate electromagnetic waves as type III radiation and whistler waves without the involvement of the classical plasma emission via the coalescence of waves. PIC simulation results of an electron-core-strahl plasma without initial current compensation are presented which describe the conversion of current-driven Langmuir oscillations/waves into type III radiation whereby simultaneously whistler waves are excited. In contrast to the classical approach of Ginzburg and Zhelezniakov (1958) after which beam-excited Langmuir waves in a two-step process are converted in electromagnetic radiation, any instability is suppressed by selecting a low strahl velocity. Rather electric field oscillations at the electron plasma frequency are triggered by the initially non-compensated current of the strahl. The arising electromagnetic fields exhibit amplitude oscillations which are caused by the superposition of the two wave modes of mixed polarisation at the point of mode coupling. This basic mechanism of wave generation and transformation has already been described in earlier papers using simple fluid models. It is also the topic of the companion paper. Besides the fundamental electromagnetic radiation, the second harmonic of nearly the same intensity has been obtained which is an indication for nonlinear currents. Measurements of Langmuir waves, type III radiation and whistler waves on board various satellites in the solar wind, in particular Parker Solar Probe (PSP) observations are analysed in the light of our results. Interpretations of earlier PIC simulations are critically reviewed.

[10] arXiv:2507.04561 [中文pdf, pdf, html, 其他]
标题: 通过在近临界固体微管表面激发表面等离子体极化激元产生的相干同步辐射
标题: Coherent synchrotron radiation by excitation of surface plasmon polariton on near-critical solid microtube surface
Bifeng Lei, Hao Zhang, Daniel Seipt, Alexandre Bonatto, Bin Qiao, Javier Resta-Lopez, Guoxing Xia, Carsten Welsch
主题: 等离子体物理 (physics.plasm-ph) ; 加速器物理 (physics.acc-ph) ; 经典物理 (physics.class-ph) ; 光学 (physics.optics)

相干同步辐射(CSR)对于开发强大的超短光源至关重要。 我们介绍了一种使用表面等离子体极化子(SPPs)的CSR生成机制,在固体近临界密度微管上共振激发SPPs。 高强度、圆偏振激光脉冲沿微管轴传播,能够有效地耦合圆柱形SPP模式。 这一过程产生了方位结构化的旋转电磁场。 这些旋转场随后约束、调制并直接加速表面电子,使其在Valilov-Cherenkov角度发射CSR。 我们进一步证明,通过提高方位对称性,螺旋调制使得CSR在所有方位方向上发射,即使完全相干性不佳,也能显著增强辐射强度。 对于高电荷束,谐波可以很好地分离。 我们的全三维粒子模拟表明,与非相干辐射相比,该方案可以生成相干性增强两个数量级的X射线。

Coherent synchrotron radiation (CSR) is vital for developing powerful ultrashort light sources. We introduce a CSR generation mechanism using surface plasmon polaritons (SPPs) resonantly excited on a solid, near-critical-density microtube. A high-intensity, circularly polarised laser pulse, propagating along the microtube axis, efficiently couples the cylindrical SPP modes. This process creates azimuthally structured, rotating electromagnetic fields. These rotating fields subsequently confine, modulate, and directly accelerate surface electrons, causing them to emit CSR in the Valilov-Cherenkov angle. We further demonstrate that by improving the azimuthal symmetry, the helical modulation enables CSR emission across all azimuthal directions, significantly enhancing radiation intensity even when full coherence is imperfect. The harmonics can be well isolated for a high charge beam. Our full 3D Particle-in-Cell simulations indicate this scheme can generate X-rays with coherence enhanced by up to two orders of magnitude compared to incoherent emission.

[11] arXiv:2507.04608 [中文pdf, pdf, html, 其他]
标题: 压缩超快摄影揭示了由密集气体激光击穿形成的等离子体内部过程在早期阶段占主导地位
标题: Compressed Ultrafast Photography of Plasmas Formed from Laser Breakdown of Dense Gases Reveals that Internal Processes Dominate Evolution at Early Times
Peng Wang, Yogeshwar Nath Mishra, Seth Pree, Lihong V. Wang, Dag Hanstorp, John P. Koulakis, Daniels Krimans, Seth Putterman
主题: 等离子体物理 (physics.plasm-ph)

压缩超快摄影(CUP)应用于氩气和氙气在高达40atm压力下的激光击穿,以获得单次事件的等离子体动力学二维图像,空间分辨率为250x100像素,等效帧率500 GHz。 通过红、绿、蓝和宽频带滤波器测量光发射随位置和时间的变化。 通常用于CUP的空间编码和时间剪切图像现在通过引入由空间积分和时间剪切未编码信号给出的约束得到增强。 这些数据提供了关于温度、不透明度、等离子体形成过程以及等离子体内部和周围环境气体中热流的见解。 恒定发射的轮廓表明,由足够密集气体形成的等离子体在具有几电子伏特温度的情况下会收缩而不是膨胀。 由相对低压气体如7atm氩气形成的等离子体可以以接近单位的发射率辐射。 将输运和不透明度建模为来自逆轫致辐射需要电离程度远高于根据Saha方程预期的值,即使通常修改以包括密度和屏蔽效应。 根据这个模型,电子和离子都与等离子体系数>1强烈耦合。 在形成后的最初几个纳秒内, 斯特藩-玻尔兹曼辐射和向周围气体的热传导太弱,无法解释观察到的冷却速率,这表明等离子体内部的输运主导其演化。 然而,等离子体本身的热传导也很小,正如热不均匀性的持续时间远长于时间尺度所表明的那样。 等离子体与周围环境隔离的事实使其成为通过所述系统和技术研究此类高密度等离子体的状态方程和流体力学的理想系统。

Compressed ultrafast photography (CUP) is applied to laser breakdown in argon and xenon under pressures up to 40atm to obtain 2D images of the plasma dynamics of single events with a spatial resolution of 250x100 pixels and an equivalent frame rate of 500 GHz. Light emission as a function of position and time is measured through red, green, blue, and broad-band filters. The spatially encoded and temporally sheared image normally used in CUP is now enhanced by the introduction of a constraint given by a spatially integrated and temporally sheared unencoded signal. The data yield insights into the temperature, opacity, the plasma formation process, and heat flow within the plasma and to the surrounding ambient gas. Contours of constant emission indicate that plasmas formed from sufficiently dense gas contract rather than expand despite having a temperature of a few eV. Plasmas formed from relatively low pressure gases such as 7atm argon can radiate with emissivity near unity. Modeling transport and opacity as arising from inverse Bremsstrahlung requires a degree of ionization that strongly exceeds expectations based on Saha's equation even as customarily modified to include density and screening. According to this model, both electrons and ions are strongly coupled with a plasma coefficient >1. During the first few nanoseconds after formation, Stefan-Boltzmann radiation and thermal conduction to ambient gas are too weak to explain the observed cooling rates, suggesting that transport within the plasma dominates its evolution. Yet, thermal conduction within the plasma itself is also small as indicated by the persistence of thermal inhomogeneities for far longer timescales. The fact that plasma is isolated from the surroundings makes it an excellent system for the study of the equation of state and hydrodynamics of such dense plasmas via the systems and techniques described.

[12] arXiv:2507.04759 [中文pdf, pdf, 其他]
标题: 氮秒脉冲MHCD制备六方氮化硼薄膜:原位等离子体诊断和生长后薄膜表征
标题: Hexagonal boron nitride thin film synthesis with a ns-pulsed MHCD: in-situ plasma diagnostics and post-growth film characterization
Belkacem Menacer (LSPM), Dimitrios Stefas (LSPM), Nikolaos Chazapis (LSPM), Claudia Lazzaroni (LSPM), Kristaq Gazeli (LSPM), Vianney Mille (LSPM)
主题: 等离子体物理 (physics.plasm-ph)

六方氮化硼(h-BN)通过等离子体增强化学气相沉积(PECVD)沉积在Si <100>晶圆($\approx$20 cm2)上,使用ns脉冲N2/Ar微空心阴极放电(MHCD)作为微等离子体源。 首次将氮化铝(AIN)用作MHCD中的介电材料,以减轻原子氧引起的薄膜污染,这是之前使用传统Al2O3介电材料时观察到的问题。 采用综合的多诊断方法对沉积的h-BN进行表征,包括拉曼光谱、扫描电子显微镜(SEM)、原子力显微镜(AFM)和X射线光电子显微镜(XPS)。 同时,使用原位诊断技术,如光学发射光谱(OES)和增强型CCD(ICCD)成像来监测等离子体特性,包括发射谱、气体温度和放电形态。 拉曼光谱显示h-BN的E2g声子模式约为1366 cm_____, 确认了成功的合成。 SEM图像显示薄膜几乎完全覆盖表面,但存在局部剥离现象。 这可能是由于Si晶圆电阻加热不均匀、快速的沉积后冷却($\sim$13 K/min)以及环境暴露所致。 AFM分析表明,在90分钟沉积后平均厚度约为33 nm($\sim$22 nm/h沉积速率)。 XPS测量显示沿晶圆直径的平均B/N原子比为$\sim$1.5。 对理想薄膜性能的偏离(例如,化学计量单位、均匀形貌)归因于等离子体引起的不均匀性(如非均匀物种通量和温度梯度)以及其他因素(如沉积后的环境暴露),这些因素影响氮和硼的掺入以及局部薄膜性能。 尽管存在这些挑战,MHCD驱动的PECVD工艺在可扩展的h-BN合成方面显示出巨大潜力,需要进一步优化反应器设计、等离子体条件和气体化学成分以生长理想的薄膜。

Hexagonal boron nitride (h-BN) is deposited on Si <100> wafer ($\approx$20 cm2) via Plasma Enhanced Chemical Vapor Deposition (PECVD) using a ns-pulsed N2/Ar Micro Hollow Cathode Discharge (MHCD) as a microplasma source. For the first time, aluminum nitride (AIN) is employed as the dielectric material in the MHCD to mitigate film contamination by atomic oxygen, an issue previously observed with conventional Al 2O3 dielectrics. A comprehensive multi-diagnostic approach is followed to characterize the deposited h-BN, including Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron microscopy (XPS). In parallel, in-situ diagnostics such as optical emission spectroscopy (OES) and intensified CCD (ICCD) imaging are used to monitor plasma properties, including emission profiles, gas temperature and discharge morphology. Raman spectra reveal the E2g phonon mode of h-BN around 1366 cm_____, confirming successful synthesis. SEM imaging reveals an almost complete surface coverage by the film, with localized delamination. This is probably due to an uneven resistive heating of the Si wafer, rapid post-deposition cooling ($\sim$13 K/min) and ambient exposure. AFM analysis indicates an average thickness of about 33 nm after 90 minutes of deposition ($\sim$22 nm/h deposition rate). XPS measurements reveal an average B/N atomic ratio of $\sim$1.5 along the wafer diameter. Deviations from ideal film properties (e.g., stoichiometric unity, uniform morphology) are attributed to plasma-induced inhomogeneities (such as non-uniform species flux and temperature gradients) among other factors (e.g., ambient exposure post-deposition), which affect nitrogen and boron incorporation and localized film properties. Despite these challenges, the MHCD-driven PECVD process demonstrates strong potential for scalable h-BN synthesis, with further optimization of the reactor design, plasma conditions, and gas chemistry required to grow ideal films.

[13] arXiv:2507.05067 [中文pdf, pdf, html, 其他]
标题: 用高斯过程回归量化平台轮廓测量的分辨率极限
标题: Quantifying Resolution Limits in Pedestal Profile Measurements with Gaussian Process Regression
Norman M. Cao, David R. Hatch, Craig Michoski, Todd A. Oliver, David Eldon, Andrew Oakleigh Nelson, Matthew Waller
主题: 等离子体物理 (physics.plasm-ph)

边缘输运屏障(ETBs)在磁约束聚变等离子体中,通常称为台阶,对于实现高约束等离子体起着关键作用。 然而,它们的特征是在短长度尺度上等离子体压力急剧上升,这使得它们在实验上难以诊断。 在这项工作中,我们使用高斯过程回归(GPR)来开发基于第一性原理的度量标准,用于量化从实验测量中推断温度、压力或其他量的可微分剖面的空间和时间分辨率限制。 尽管我们专注于台阶,但这些方法是完全通用的,可以应用于任何涉及从离散测量中推断剖面的情况。 首先,我们将GPR与低通滤波建立对应关系,给出了与GPR引起的平滑相关的有效“截止频率”的显式表达式。 其次,我们引入了一个新的信息论度量,\(N_{eff}\),它衡量对剖面或其导数的推断值有贡献的有效数据点数量。 这些度量使能够对“过拟合”和“过度正则化”之间的权衡进行定量评估,为GPR的使用者和消费者提供了一种系统的方法来评估推断剖面的可信度。 我们将这些工具应用于在静态和动态设置中使用GPR的实用建议,并展示了它们在利用DIII-D托卡马克的测量数据推断台阶剖面中的应用。

Edge transport barriers (ETBs) in magnetically confined fusion plasmas, commonly known as pedestals, play a crucial role in achieving high confinement plasmas. However, their defining characteristic, a steep rise in plasma pressure over short length scales, makes them challenging to diagnose experimentally. In this work, we use Gaussian Process Regression (GPR) to develop first-principles metrics for quantifying the spatiotemporal resolution limits of inferring differentiable profiles of temperature, pressure, or other quantities from experimental measurements. Although we focus on pedestals, the methods are fully general and can be applied to any setting involving the inference of profiles from discrete measurements. First, we establish a correspondence between GPR and low-pass filtering, giving an explicit expression for the effective `cutoff frequency' associated with smoothing incurred by GPR. Second, we introduce a novel information-theoretic metric, \(N_{eff}\), which measures the effective number of data points contributing to the inferred value of a profile or its derivative. These metrics enable a quantitative assessment of the trade-off between `over-fitting' and `over-regularization', providing both practitioners and consumers of GPR with a systematic way to evaluate the credibility of inferred profiles. We apply these tools to develop practical advice for using GPR in both time-independent and time-dependent settings, and demonstrate their usage on inferring pedestal profiles using measurements from the DIII-D tokamak.

[14] arXiv:2507.05151 [中文pdf, pdf, html, 其他]
标题: 非量化粒子算法用于非线性Vlasov-Poisson系统
标题: Dequantized particle algorithm for the nonlinear Vlasov-Poisson system
Hong Qin, Michael Q. May, Jacob Molina
评论: 13页,5图
主题: 等离子体物理 (physics.plasm-ph) ; 计算物理 (physics.comp-ph) ; 量子物理 (quant-ph)

我们提出了一种用于Vlasov--Poisson (VP)系统的去量化算法,称为去量化粒子算法,通过系统地去量化底层的多体量子理论。 从二次量化哈密顿量描述出发,我们推导出一个有限维的去量化系统,并证明它提供了Schrödinger--Poisson (SP)方程的结构保持离散化。 通过Wigner或Husimi变换,当量子效应可以忽略时,这种离散化提供了一种对VP系统的高效近似。 与在6D相空间中表述的传统结构保持算法不同,这个去量化粒子算法在3D配置空间中运行,在适当条件下可能提供更紧凑和高效的物理信息表示。 一个使用仅97个去量化粒子模拟的经典非线性双流不稳定性数值示例,展示了该算法的效率、准确性和守恒性质,并证实了其作为开发用于动力学等离子体动力学的量子和量子启发经典算法的基础潜力。

We present a dequantization algorithm for the Vlasov--Poisson (VP) system, termed the dequantized particle algorithm, by systematically dequantizing the underlying many-body quantum theory. Starting from the second-quantized Hamiltonian description, we derive a finite-dimensional dequantized system and show that it furnishes a structure-preserving discretization of the Schr\"odinger--Poisson (SP) equations. Through the Wigner or Husimi transformations, this discretization provides an efficient approximation of the VP system when quantum effects are negligible. Unlike conventional structure-preserving algorithms formulated in 6D phase space, this dequantized particle algorithm operates in 3D configuration space, potentially offering more compact and efficient representations of physical information under appropriate conditions. A numerical example of the classical nonlinear two-stream instability, simulated using merely 97 dequantized particles, demonstrates the efficiency, accuracy, and conservation properties of the algorithm and confirms its potential as a foundation for developing quantum and quantum-inspired classical algorithms for kinetic plasma dynamics.

[15] arXiv:2507.05166 [中文pdf, pdf, html, 其他]
标题: M3D-C1中的自举电流建模
标题: Bootstrap Current Modeling in M3D-C1
Saurabh Saxena, Nathaniel Ferraro, Mike F. Martin, Adelle M. Wright
评论: 15页,8图
主题: 等离子体物理 (physics.plasm-ph)

自举电流在磁约束等离子体的平衡中起着关键作用,特别是在准对称(QS) stellarators 和 tokamaks 中,它可以代表大部分的电流密度。 准确建模这种电流对于理解这些配置的磁流体动力学(MHD)平衡和稳定性至关重要。 本研究通过实现自洽的物理模型来扩展 M3D-C1 这个扩展 MHD 代码的建模能力,用于自举电流。 它采用了两种分析框架:广义 Sauter 模型(Sauter 等 (1999)),以及修订后的 Sauter 类似模型(Redl 等 (2021))。 Landreman 等 (2022) 描述的同构性被用来将这些模型应用于准对称 stellarators。 在 M3D-C1 中的实现与经典代码 NEO、XGCa 和 SFINCS 进行了基准测试,显示出良好的一致性。 这些改进使 M3D-C1 能够自洽地计算轴对称和准对称配置中等离子体电流的经典贡献,为这些配置中的等离子体行为提供了更准确的表示。 还提出了一种使用 SFINCS 评估经典输运的流程,该流程使用 M3D-C1 计算任意环向平衡。 此工作流程使得在偏离轴对称或准对称的情况(例如通过发展 MHD 不稳定性)下,能够定量评估 Sauter 类似模型的误差。

Bootstrap current plays a crucial role in the equilibrium of magnetically confined plasmas, particularly in quasisymmetric (QS) stellarators and in tokamaks, where it can represent bulk of the electric current density. Accurate modeling of this current is essential for understanding the magnetohydrodynamic (MHD) equilibrium and stability of these configurations. This study expands the modeling capabilities of M3D-C1, an extended-MHD code, by implementing self-consistent physics models for bootstrap current. It employs two analytical frameworks: a generalized Sauter model (Sauter et al. (1999)), and a revised Sauter-like model (Redl et al. (2021)). The isomorphism described by Landreman et al. (2022) is employed to apply these models to quasisymmetric stellarators. The implementation in M3D-C1 is benchmarked against neoclassical codes, including NEO, XGCa, and SFINCS, showing excellent agreement. These improvements allow M3D-C1 to self-consistently calculate the neoclassical contributions to plasma current in axisymmetric and quasisymmetric configurations, providing a more accurate representation of the plasma behavior in these configurations. A workflow for evaluating the neoclassical transport using SFINCS with arbitrary toroidal equilibria calculated using M3D-C1 is also presented. This workflow enables a quantitative evaluation of the error in the Sauter-like model in cases that deviate from axi- or quasi-symmetry (e.g., through the development of an MHD instability).

交叉提交 (展示 8 之 8 条目 )

[16] arXiv:2507.02897 (交叉列表自 cs.LG) [中文pdf, pdf, html, 其他]
标题: 符合法规的聚变人工智能:基于实时图像分析的托卡马克偏滤器分离控制
标题: Regulation Compliant AI for Fusion: Real-Time Image Analysis-Based Control of Divertor Detachment in Tokamaks
Nathaniel Chen, Cheolsik Byun, Azarakash Jalalvand, Sangkyeun Kim, Andrew Rothstein, Filippo Scotti, Steve Allen, David Eldon, Keith Erickson, Egemen Kolemen
主题: 机器学习 (cs.LG) ; 计算机视觉与模式识别 (cs.CV) ; 系统与控制 (eess.SY) ; 等离子体物理 (physics.plasm-ph)

虽然人工智能(AI)在聚变控制方面表现出色,但其固有的黑箱特性将使在监管环境中的合规实施成为一项挑战。 本研究实现了并验证了一个实时AI支持的线性和可解释的控制系统,成功地对DIII-D下部偏滤器相机进行了偏滤器分离控制。 使用D2气体,我们展示了反馈偏滤器分离控制,分离和重新结合的目标之间的平均绝对差异为2%。 这种自动训练和线性处理框架可以扩展到任何基于图像的诊断,以满足未来聚变反应堆所需的监管合规控制器。

While artificial intelligence (AI) has been promising for fusion control, its inherent black-box nature will make compliant implementation in regulatory environments a challenge. This study implements and validates a real-time AI enabled linear and interpretable control system for successful divertor detachment control with the DIII-D lower divertor camera. Using D2 gas, we demonstrate feedback divertor detachment control with a mean absolute difference of 2% from the target for both detachment and reattachment. This automatic training and linear processing framework can be extended to any image based diagnostic for regulatory compliant controller necessary for future fusion reactors.

[17] arXiv:2507.03119 (交叉列表自 cs.LG) [中文pdf, pdf, 其他]
标题: 理想MHD平衡的神经网络求解器
标题: Neural-Network solver of ideal MHD equilibria
Timo Thun, Andrea Merlo, Rory Conlin, Dario Panici, Daniel Böckenhoff
评论: 提交至《核聚变》,16页,8图
主题: 机器学习 (cs.LG) ; 人工智能 (cs.AI) ; 等离子体物理 (physics.plasm-ph)

我们提出一种新方法,通过用人工神经网络参数化傅里叶模式来计算三维磁流体动力学平衡,并将其与传统求解器计算的平衡进行比较。 然后,在实空间中对整个体积的非线性全局力残差进行一阶优化器最小化。 我们已经观察到,计算成本与现有代码计算得到相同最小残差具有竞争力。 随着计算成本的增加,神经网络实现了更低的残差最小值,确立了力残差的新下限。 我们使用了最小复杂度的神经网络,并预期在不仅解决单个平衡问题,而且在计算适用于连续平衡分布的神经网络模型方面,将有显著改进。

We present a novel approach to compute three-dimensional Magnetohydrodynamic equilibria by parametrizing Fourier modes with artificial neural networks and compare it to equilibria computed by conventional solvers. The full nonlinear global force residual across the volume in real space is then minimized with first order optimizers. Already,we observe competitive computational cost to arrive at the same minimum residuals computed by existing codes. With increased computational cost,lower minima of the residual are achieved by the neural networks,establishing a new lower bound for the force residual. We use minimally complex neural networks,and we expect significant improvements for solving not only single equilibria with neural networks,but also for computing neural network models valid over continuous distributions of equilibria.

[18] arXiv:2507.03245 (交叉列表自 physics.comp-ph) [中文pdf, pdf, html, 其他]
标题: 实时预测等离子体不稳定性,采用稀疏网格加速的优化动态模式分解
标题: Real-time prediction of plasma instabilities with sparse-grid-accelerated optimized dynamic mode decomposition
Kevin Gill, Ionut-Gabriel Farcas, Silke Glas, Benjamin J. Faber
评论: 28页,14图,8表
主题: 计算物理 (physics.comp-ph) ; 计算工程、金融与科学 (cs.CE) ; 数值分析 (math.NA) ; 等离子体物理 (physics.plasm-ph)

参数化数据驱动的降阶模型(ROM)在嵌入大量输入参数的依赖关系方面对于在大规模问题中实现多查询任务至关重要。 这些任务,包括设计优化、控制和不确定性量化,对于在现实应用中开发数字孪生体是必不可少的。 然而,由于维度灾难,标准的训练数据生成方法在计算上是不可行的,因为其成本随着输入数量的增加呈指数级增长。本文研究了使用稀疏网格插值与(L)-Leja点对参数化数据驱动的ROM进行高效训练,特别针对高维输入参数空间的情况。 (L)-Leja点是嵌套的且增长缓慢,在低到中等维度设置中产生具有低基数的稀疏网格,使其成为大规模、计算昂贵问题的理想选择。 专注于托卡马克实验中等离子体微观不稳定性的一个代表性现实应用,我们通过优化动态模式分解(optDMD)和基于(L)-Leja点的稀疏网格,构建了完整的5D陀螺动力学分布函数的参数化ROM。 我们在两种场景中进行了详细实验:首先,Cyclone Base Case基准测试评估了optDMD ROM在训练时间范围之外以及在横向波数变化中的预测能力。其次,对于一个具有六个输入参数的真实电子温度梯度驱动的微观不稳定性模拟,我们证明可以通过稀疏网格仅使用$28$次高保真陀螺动力学模拟的成本构建出准确的参数化optDMD ROM。 在聚变研究的更广泛背景下,这些结果展示了基于稀疏网格的参数化ROM在实现原本难以处理的多查询任务方面的潜力。

Parametric data-driven reduced-order models (ROMs) that embed dependencies in a large number of input parameters are crucial for enabling many-query tasks in large-scale problems. These tasks, including design optimization, control, and uncertainty quantification, are essential for developing digital twins in real-world applications. However, standard training data generation methods are computationally prohibitive due to the curse of dimensionality, as their cost scales exponentially with the number of inputs.This paper investigates efficient training of parametric data-driven ROMs using sparse grid interpolation with (L)-Leja points, specifically targeting scenarios with higher-dimensional input parameter spaces. (L)-Leja points are nested and exhibit slow growth, resulting in sparse grids with low cardinality in low-to-medium dimensional settings, making them ideal for large-scale, computationally expensive problems. Focusing on gyrokinetic simulations of plasma micro-instabilities in fusion experiments as a representative real-world application, we construct parametric ROMs for the full 5D gyrokinetic distribution function via optimized dynamic mode decomposition (optDMD) and sparse grids based on (L)-Leja points. We perform detailed experiments in two scenarios: First, the Cyclone Base Case benchmark assesses optDMD ROM prediction capabilities beyond training time horizons and across variations in the binormal wave number. Second, for a real-world electron temperature gradient driven micro-instability simulation featuring six input parameters, we demonstrate that an accurate parametric optDMD ROM can be constructed at a cost of only $28$ high-fidelity gyrokinetic simulations thanks to sparse grids. In the broader context of fusion research, these results demonstrate the potential of sparse grid-based parametric ROMs to enable otherwise intractable many-query tasks.

[19] arXiv:2507.03757 (交叉列表自 cond-mat.stat-mech) [中文pdf, pdf, html, 其他]
标题: Kappa分布的超统计语言
标题: Kappa distributions in the language of superstatistics
Sergio Davis, Biswajit Bora, Cristian Pavez, Leopoldo Soto
主题: 统计力学 (cond-mat.stat-mech) ; 等离子体物理 (physics.plasm-ph)

速度的kappa分布经常出现在研究地球磁层中的无碰撞等离子体、太阳风以及其他粒子无法达到热平衡的背景下。最初是通过使用Tsallis的非广延统计来证明的,现在有其他框架提供了对这些分布的见解,例如超统计。在本工作中,我们回顾了在超统计框架下无碰撞等离子体的多粒子和单粒子kappa分布的推导,作为使用非广延统计的替代方法。我们还展示了超统计框架在计算kappa分布下的期望值方面的实用性。还讨论了超统计形式主义在kappa分布等离子体的相关性、温度和熵方面的某些后果。

The kappa distribution of velocities appears routinely in the study of collisionless plasmas present in Earth's magnetosphere, the solar wind among other contexts where particles are unable to reach thermal equilibrium. Originally justified through the use of Tsallis' non-extensive statistics, nowadays there are alternative frameworks that provide insight into these distributions, such as superstatistics. In this work we review the derivation of the multi-particle and single-particle kappa distributions for collisionless plasmas within the framework of superstatistics, as an alternative to the use of non-extensive statistics. We also show the utility of the superstatistical framework in the computation of expectation values under kappa distributions. Some consequences of the superstatistical formalism regarding correlations, temperature and entropy of kappa-distributed plasmas are also discussed.

[20] arXiv:2507.03812 (交叉列表自 cs.MS) [中文pdf, pdf, 其他]
标题: 面向曲线坐标表示的内存和计算优化几何多重网格GMGPolar——用于聚变等离子体的应用
标题: Memory- and compute-optimized geometric multigrid GMGPolar for curvilinear coordinate representations -- Applications to fusion plasma
Julian Litz, Philippe Leleux, Carola Kruse, Joscha Gedicke, Martin J. Kühn
评论: 29页,10图,4表
主题: 数学软件 (cs.MS) ; 等离子体物理 (physics.plasm-ph)

托卡马克聚变反应堆正在积极研究作为一种实现等离子体聚变能源生产的方法。 然而,由于建造聚变反应堆和进行物理实验所需的高昂成本和时间,数值实验对于理解托卡马克内的等离子体物理、支持设计和工程阶段以及优化未来反应堆设计是必不可少的。 几何多重网格方法是许多从偏微分方程离散化中出现的问题的最优求解器。 已经证明,多重网格求解器GMGPolar以线性复杂度求解二维gyrokinetic泊松方程,并且与其他最先进的求解器相比,只需要很小的内存需求。 在本文中,我们提出了一种完全重构的面向对象版本的GMGPolar,该版本提供了两种不同的无矩阵实现。 其中,我们利用Sherman-Morrison公式从圆形线性求解器中求解循环三对角系统,而不会产生额外的填充,并应用重新排序以优化圆形和径向平滑操作的缓存访问。 通过Give方法,内存需求进一步减少,通常的测试案例可以获得四到七倍的速度提升。 对于Take方法,可以获得16到18倍的速度提升。

Tokamak fusion reactors are actively studied as a means of realizing energy production from plasma fusion. However, due to the substantial cost and time required to construct fusion reactors and run physical experiments, numerical experiments are indispensable for understanding plasma physics inside tokamaks, supporting the design and engineering phase, and optimizing future reactor designs. Geometric multigrid methods are optimal solvers for many problems that arise from the discretization of partial differential equations. It has been shown that the multigrid solver GMGPolar solves the 2D gyrokinetic Poisson equation in linear complexity and with only small memory requirements compared to other state-of-the-art solvers. In this paper, we present a completely refactored and object-oriented version of GMGPolar which offers two different matrix-free implementations. Among other things, we leverage the Sherman-Morrison formula to solve cyclic tridiagonal systems from circular line solvers without additional fill-in and we apply reordering to optimize cache access of circular and radial smoothing operations. With the Give approach, memory requirements are further reduced and speedups of four to seven are obtained for usual test cases. For the Take approach, speedups of 16 to 18 can be attained.

[21] arXiv:2507.04527 (交叉列表自 astro-ph.HE) [中文pdf, pdf, html, 其他]
标题: 模拟具有超流涡旋的中子星地壳的新分子动力学方法
标题: New Molecular Dynamics Methods for Simulating Neutron Star Crusts with Superfluid Vortices
M. E. Caplan, N. T. Smith
评论: 3页,1图,发表于RNAAS。图1的动画可在“anc”文件夹(附加工具)文件中找到
期刊参考: RNAAS,9,162(2025)
主题: 高能天体物理现象 (astro-ph.HE) ; 其他凝聚态物理 (cond-mat.other) ; 核理论 (nucl-th) ; 等离子体物理 (physics.plasm-ph)

超流体涡旋在中子星地壳中被认为被地壳中的核晶格所钉扎。因此,自旋跳变中超流体涡旋的解钉扎促使我们用分子动力学方法明确研究涡旋-地壳相互作用。在本工作中,我们提出一种新的分子动力学方法来表征地壳对刚性涡旋的响应。当涡旋钉扎力和最近邻库仑力相当时,我们观察到一种定性上新的晶格牵连现象,这对地壳的弹性演化有重要意义。

Superfluid vortices in neutron star crusts are thought to be pinned to the lattice of nuclei in the crust. The unpinning of superfluid vortices in spin glitches therefore motivates us to study the vortex-crust interaction explicitly with molecular dynamics. In this work, we present a new molecular dynamics methods to characterize the response of the crust to a rigid vortex. When vortex pinning forces and nearest neighbor Coulomb forces are comparable, we observe a qualitatively new phenomena of lattice entrainment with implications for the elastic evolution of the crust.

[22] arXiv:2507.04596 (交叉列表自 math-ph) [中文pdf, pdf, html, 其他]
标题: 扰动环形涡旋显示内部单连通拓扑
标题: Perturbed Toroidal Vortices Display Internal Simply Connected Topology
Taosif Ahsan, Samuel A. Cohen, Alan H. Glasser
评论: 5页的正文论文,3幅图表,6个子图。13页的补充材料,其中详细证明了相关内容
主题: 数学物理 (math-ph) ; 流体动力学 (physics.flu-dyn) ; 等离子体物理 (physics.plasm-ph)

这项工作表明,扰动零螺旋度涡旋的内部表现出具有新月形边界的简单连通拓扑。 流体和磁涡旋中的通量面通过分析方法进行了研究,而在等离子体约束背景下粒子轨迹则通过数值方法进行了检查,证明了环状和简单连通拓扑的存在。 这种新的拓扑结构出现在一大类扰动中,振幅和空间变化可以任意小。 这项工作的推论证明了在零螺旋度涡旋的奇宇称扰动下,场线的闭合性。

This work shows that the interiors of perturbed zero-helicity vortices display simply connected topology with a crescent-shaped boundary. Flux surfaces in fluid and magnetic vortices were explored analytically, while particle trajectories in the context of plasma confinement were examined numerically, demonstrating the existence of both toroidal and simply connected topologies. This new topology appears for perturbations in a broad class, with amplitudes and spatial variance allowed to be arbitrarily small. A corollary of this work proves the closedness of field lines under odd-parity perturbations of zero-helicity vortices.

[23] arXiv:2507.04727 (交叉列表自 astro-ph.CO) [中文pdf, pdf, html, 其他]
标题: 关于XRISM对星系团介质中湍流的X射线测量的解释:与宇宙学模拟的比较
标题: On the interpretation of XRISM X-ray measurements of turbulence in the intracluster medium: a comparison with cosmological simulations
F. Vazza, G. Brunetti
评论: 5页,5图,于2025年6月24日提交至A&A
主题: 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA) ; 等离子体物理 (physics.plasm-ph)

我们研究了通过XRISM在室女座星系团中利用X射线光谱学最近测量的湍流气体运动特性,是否与大尺度上由典型高分辨率宇宙学模拟产生的“经典”流体图景存在矛盾。 我们使用了一个类似室女座星系团的高分辨率模拟,并表明模拟中测量到的类似Kolmogorov的湍流能够产生与XRISM对室女座星系团观测结果完全兼容的速度结构函数和线宽。 这些结果突显了由星系团内介质中湍流的不均匀性以及观测中的X射线加权共同驱动的偏差,并似乎缓解了XRISM数据与当前数值模拟之间的矛盾,表明当前观测数据并不需要一个比Kolmogorov更陡峭的湍流谱。

We investigate whether the properties of turbulent gas motions recently measured via X-ray spectroscopy in the Coma cluster of galaxies by XRISM are in tension with the "classical" fluid picture of the intracluster medium on large scales, as produced by a typical high-resolution cosmological simulation. We use a high-resolution simulation of Coma-like cluster of galaxies and show that the Kolmogorov-like turbulence measured in the simulation yields to velocity structure functions and line-width that fully compatible with those measured by the XRISM observation of Coma. These results highlight the combined biases driven by the inhomogeneity of turbulence in the intracluster medium and by the X-ray weighting in observations, and appear to release the tension between the XRISM data and current numerical simulations, showing that a turbulent spectrum much steeper than Kolmogorov is not required by current observational data.

替换提交 (展示 4 之 4 条目 )

[24] arXiv:2410.12016 (替换) [中文pdf, pdf, html, 其他]
标题: 电子尺度托卡马克湍流的亚网格模型
标题: A Subgrid Model of Electron-Scale Tokamak Turbulence
Stefan Tirkas, Yang Chen, Scott Parker
评论: 11页,9图。以下文章已提交至《等离子体物理》
期刊参考: 物理等离子体 32, 032504 (2025)
主题: 等离子体物理 (physics.plasm-ph)

这里展示了一个子网格电子温度梯度(ETG)模型,该模型通过对GENE代码中局部电子尺度湍流在空间和时间上的中间尺度进行平均,将其包含在全局离子温度梯度(ITG)GEM模拟中。 这种方法得到的离子尺度方程包含了来自ETG湍流的电子热输运以及电子尺度湍流对离子尺度的影响。 使用GENE在不同的径向位置进行了通量管ETG Cyclone Base Case模拟,并将通量的一个动力学形式作为源项添加到离子尺度全局GEM模拟中。 构建了ETG热通量的解析径向分布,并在多个径向位置与通量管结果进行了比较。 考虑了ITG与ETG湍流热通量水平的不同比例,并讨论了在全局GEM模拟中捕捉ETG热输运的结果。 进一步讨论了在ETG模拟中发现的ETG条纹势和中间尺度极向流与离子尺度耦合的可能性。

A subgrid electron-temperature-gradient (ETG) model is demonstrated here which averages local electron-scale turbulence from the GENE code over intermediate scales in space and time to include in global ion-temperature-gradient (ITG) GEM simulations. This approach results in ion-scale equations which include the electron heat transport from ETG turbulence and the effects of electron-scale turbulence on the ion scale. Flux-tube ETG Cyclone Base Case simulations are carried out using GENE at different radial locations and a kinetic form of the flux is added to ion-scale global GEM simulations as a source term. Analytic radial profiles of ETG heat flux are constructed and compared to flux-tube results at multiple radial locations. Different ratios of ITG to ETG turbulent heat flux levels are considered and the results of capturing ETG heat transport in global GEM simulations are discussed. Possibilities for coupling of the ETG streamer potential and intermediate-scale zonal flows found in ETG simulations to the ion scale are further discussed.

[25] arXiv:2412.07725 (替换) [中文pdf, pdf, html, 其他]
标题: 一种用于等离子体中能量损失、熵演化和融合性能的统一哈密顿公式
标题: A Unified Hamiltonian Formulation for Energy Loss, Entropy Evolution, and Fusion Performance in Plasmas
Joseph Samper Finberg
主题: 等离子体物理 (physics.plasm-ph) ; 数学物理 (math-ph)

我们为等离子体动力学开发了一个全面的哈密顿表述,该表述统一了无碰撞的导体动力学和有碰撞的过程。 我们的框架严格描述了从麦克斯韦分布到非麦克斯韦分布转变过程中自由能和熵的演化,明确地将微观湍流过程与宏观的能量约束和聚变性能度量耦合在一起。 与标准的导体动力学处理方法不同,后者将碰撞视为次要扰动,我们的方法直接将碰撞算子纳入哈密顿结构中,从而考虑了不可逆耗散和熵产生。 我们推导了定量关系,将湍流强度、熵产生、能量约束时间和聚变产率联系起来。 我们的工作建立在Helander和Plunk最近的能量界限和最优模式分析以及Zhdankin的广义熵产生框架之上,从而在微观动力学和反应堆尺度性能之间建立了桥梁。

We develop a comprehensive Hamiltonian formulation for plasma dynamics that unifies collisionless gyrokinetic and collisional processes. Our framework rigorously describes the evolution of free energy and entropy during the transition from Maxwellian to non-Maxwellian distributions, explicitly coupling microscopic turbulent processes with macroscopic measures of energy confinement and fusion performance. Unlike standard gyrokinetic treatments that treat collisions as a minor perturbation, our approach incorporates a collision operator directly into the Hamiltonian structure, thereby accounting for irreversible dissipation and entropy production. We derive quantitative relations linking turbulence intensity, entropy production, energy confinement time and fusion yield. Our work builds on recent energetic bounds and optimal mode analyses by Helander and Plunk and on Zhdankin's generalised entropy-production framework, thus providing a bridge between microscopic kinetics and reactor-scale performance.

[26] arXiv:2501.19136 (替换) [中文pdf, pdf, html, 其他]
标题: 随机粒子加速的有效理论,应用于磁化湍流
标题: Effective theory for stochastic particle acceleration, with application to magnetized turbulence
M. Lemoine (APC)
评论: 将出现在《Phys. Rev. E》上的版本
主题: 等离子体物理 (physics.plasm-ph) ; 高能天体物理现象 (astro-ph.HE) ; 太阳与恒星天体物理学 (astro-ph.SR)

粒子在湍流等离子体中的加速物理是一个广受关注的主题,由于专门的大规模数值实验,这一领域正在迅速发展。 本文的第一部分提出了一个有效的随机费米加速理论,该理论涵盖了理想电场中所有非共振加速形式,并适用于一般情况。 它结合了一个精确的方程,将能量化率与速度场的统计特性联系起来,并结合了粒子通过结构(即强速度梯度区域)传输的统计模型。 在第二部分中,该形式化方法被应用于磁流体动力学湍流,以获得对平流和扩散系数逐尺度贡献的全面评估。 加速在粒子可以被困在结构中的涡旋回转时间尺度上达到峰值,或在大振幅湍流中与磁场线剧烈弯曲相关的强烈结构中(如前所述)。 这些空间不均匀的快速加速机制为丰富的现象学奠定了基础。 我们讨论了获得的标度关系,它们的解释,并展示了这些结果与现有的数值结果相符。

The physics of particle acceleration in turbulent plasmas is a topic of broad interest, which is making rapid progress thanks to dedicated, large-scale numerical experiments. The first part of this paper presents an effective theory of stochastic Fermi acceleration, which subsumes all forms of non-resonant acceleration in ideal electric fields and is applicable in generic settings. It combines an exact equation connecting the energization rate to the statistics of the velocity field with a statistical model of particle transport through the structures (i.e., the regions of strong velocity gradients). In a second part, this formalism is applied to magnetohydrodynamic turbulence to obtain a comprehensive assessment of the scale-by-scale contributions to the advection and diffusion coefficients. Acceleration peaks on scales where particles can be trapped inside structures for an eddy turn-around time, or in intense structures associated with sharp bends of the magnetic field lines in large-amplitude turbulence (as reported earlier). These spatially inhomogeneous, rapid acceleration regimes pave the way for a rich phenomenology. We discuss the scalings obtained, their interpretation and show that the findings compare satisfactorily with existing numerical results.

[27] arXiv:2506.16676 (替换) [中文pdf, pdf, html, 其他]
标题: PETSC用于托卡马克流体模型的快速求解器——第一部分
标题: Fast solvers for Tokamak fluid models with PETSC -- Part I
Mark F. Adams, Jin Chen, Benjamin Sturdevant
主题: 等离子体物理 (physics.plasm-ph) ; 性能 (cs.PF)

这项工作开始使用多重网格方法开发用于托卡马克科学和工程相关磁流体动力学(MHD)模型的快速、可扩展求解器。 这些托卡马克模型在环向坐标中具有一个显著的方向,该方向部分与磁导场对齐,这主导了等离子体动力学。 所有托卡马克模型都利用这一结构,例如 https://nimrodteam.org 的 NIMROD 使用 $2D$,环向平面中的非结构化高阶有限元以及环向坐标中的傅里叶模式,而 $3D$,扩展的MHD代码 \textit{M3D-C1}\footnote{https://m3dc1.pppl.gov} 使用 $2D$,环向平面中的非结构化 $C^1$元素以及环向方向中的三次 Hermite 函数。 这种结构建议首先处理环向坐标,这在公式层面由\textit{NIMROD}实现,但\textit{M3D-C1}方法则将其保留在代数系统中,在每个时间步长的隐式时间积分器中求解。 这项工作通过在现有的 PETSC(https://petsc.org -- 可扩展的科学计算工具包)块雅可比求解器中添加半粗化多重网格方法,解决了\textit{M3D-C1}速度求解中的环向坐标,新增的代码很少,允许使用更小的雅可比子域,这些子域更适合现代高度并行的硬件。 在 SPARC(https://cfs.energy/technology/sparc 破裂)的自洽奔逃电子模型上展示了这种新求解器配置的竞争力,并概述了这种新方法开发的下一步计划。

This work begins the development of fast, scalable solvers for scientific and engineering-relevant magnetohydrodynamics (MHD) models of tokamaks using multigrid methods. These tokamak models are characterized by a distinguished direction in the toroidal coordinate that is partially aligned with the magnetic guide field, which dominates the plasma dynamics. All tokamak models exploit this structure, for example, NIMROD at https://nimrodteam.org uses $2D$, unstructured, high-order finite elements in the poloidal plane with Fourier modes in the toroidal coordinate, and the $3D$, extended MHD code \textit{M3D-C1}\footnote{https://m3dc1.pppl.gov} uses $2D$, unstructured $C^1$ elements in the poloidal plane with cubic Hermite functions in the toroidal direction. This structure suggests addressing the toroidal coordinate first, which \textit{NIMROD} does at the formulation level, but the \textit{M3D-C1} approach leaves in the algebraic system to be solved at each time step in an implicit time integrator. This work addressed the toroidal coordinate in the \textit{M3D-C1} velocity solve by adding semi-coarsening multigrid to the existing PETSC at https://petsc.org -- Portable, Extensible Toolkit for Scientific Computation -- block Jacobi solver, with the addition of little new code that allows for smaller Jacobi subdomains that are better suited to contemporary, highly parallel, hardware. Competitive performance of this new solver configuration is demonstrated on a self-consistent runaway electron model of a SPARC at https://cfs.energy/technology/sparc disruption, and the next steps in the development of this new approach are outlined.

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