等离子体物理
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显示 2025年10月03日， 星期五 新的列表
- [1] arXiv:2510.01289 [中文pdf, pdf, 其他]
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标题： 四类线性发散MHD通道在单向施加磁场下控制电场、电流密度和体积功率密度的标量显式表达式的详细推导标题： Detailed Derivation of the Scalar Explicit Expressions Governing the Electric Field, Current Density, and Volumetric Power Density in the Four Types of Linear Divergent MHD Channels Under a Unidirectional Applied Magnetic Field评论： 41页，8图，4表，已发表的期刊文章，同行评审，开放获取期刊参考： 当代数学。第6卷，第4期，第4060-4100页，https://ojs.wiserpub.com/index.php/CM/article/view/6918 (2025)主题： 等离子体物理 (physics.plasm-ph)
当前研究属于等离子体物理和电力工程中的应用数学领域，其中利用描述磁流体动力学（MHD）线性二维发散超音速通道内电场矢量和电流密度矢量的代数方程的数学分析，推导出这些重要场的解析表达式，以及体积功率密度（单位体积等离子体通道的输出电功率）的封闭形式方程。 此处提出的表达式从理论上描述了MHD通道作为开放式磁流体动力学（OCMHD）发电机中的电能来源的运行情况。 本文涵盖了四种常见的MHD线性通道类型：即（1）连续电极法拉第通道，（2）线性霍尔通道，（3）分段电极法拉第通道，以及（4）对角电极通道。 数学结果、其详细推导以及配套的图形说明有助于正确决定哪种通道类型最适合特定的应用。在典型的运行条件下，等离子体电导率为5 S/m，磁场为5 T，等离子体速度为2000 m/s，以及优化的负载因子为0.5时，我们估计连续电极法拉第通道（霍尔参数为1）的以下数值（绝对值）：有用电场（跨外部电负载）：5 kV/m，有用电流密度（通道内终端电极之间）：12.5 kA/m²，体积功率密度（由负载每单位体积等离子体耗散）：62.5 MW/m³，电效率（对于电场或电压）：50%。 对于线性霍尔通道（霍尔参数为5），这些定量性能值变为25 kV/m，4.808 kA/m²，120.19 MW/m³，以及46.30%。
The current study belongs to the field of applied mathematics in plasma physics and electric power, where mathematical analysis of the algebraic equations governing the electric field vector, and the electric-current density field vector within a Magnetohydrodynamic (MHD) linear two-dimensional divergent supersonic channel is utilized to derive analytical expressions for these important fields, as well as closed-form equations for the volumetric power density (output electric power per unit volume of the plasma channel). The expressions presented here describe analytically the operation of the MHD channel as an electric power source within an Open-Cycle Magnetohydrodynamic (OCMHD) generator. The four common types of the MHD linear channels are covered here: namely, (1) continuous-electrode Faraday channel, (2) linear Hall channel, (3) segmented-electrode Faraday channel, and (4) diagonal-electrode channel. The mathematical results, their detailed derivation, and the companion graphical illustrations aid in making a proper decision regarding which channel type is the most suitable for a given application.Under typical operational conditions of 5 S/m plasma electric conductivity, 5 T magnetic field, and 2,000 m/s plasma speed, as well as an optimized load factor of 0.5, we estimate the following numerical values (unsigned magnitudes) for the continuous-electrode Faraday channel (with a Hall parameter of 1): useful electric field (across the external electric load): 5 kV/m, useful electric current-density (between the terminal electrodes within the channel): 12.5 kA/m2 , volumetric power density (dissipated by the load per unit volume of plasma): 62.5 MW/m3 , and electric efficiency (for the electric field or voltage): 50%. For the Halllinear channel (with a Hall parameter of 5), these quantitative performance values become25 kV/m, 4.808 kA/m2, 120.19 MW/m3, and 46.30%.
- [2] arXiv:2510.01573 [中文pdf, pdf, html, 其他]
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标题： 无碰撞临界磁化等离子体中逆磁能转移的抑制标题： Suppression of inverse magnetic energy transfer in collisionless marginally magnetized plasmas主题： 等离子体物理 (physics.plasm-ph) ; 高能天体物理现象 (astro-ph.HE)
我们通过第一性原理数值模拟和分析理论，研究衰减的无碰撞等离子体中，中等至高$\beta$值下的磁能反向级联。 我们发现，由压力各向异性驱动的不稳定性，特别是火绳不稳定性，通过消除磁张力来抑制由重联驱动的磁结构合并（即反向传递）。 这种抑制使得这些结构保持拉长，并被限制在与粒子的伦德斯特罗姆半径相当的尺度内。 存在足够强的磁引导场，或者初始磁结构尺寸与伦德斯特罗姆半径之间更大的尺度分离，可以恢复系统反向传递磁能的能力。 这些结果表明，在无碰撞等离子体中，反向能量传递并非必然发生，而是对磁化程度高度敏感。 在天体物理背景下，这揭示了一种可能使Weibel生成的种子磁场无法一致合并的微观机制，可能限制其在宇宙磁星形成中的作用。
We investigate the inverse cascade of magnetic energy in decaying, collisionless plasmas with moderate to high-$\beta$ values via first-principles numerical simulations and analytical theory. We find that pressure-anisotropy-driven instabilities, in particular the firehose instability, suppress reconnection-driven coalescence of magnetic structures (i.e., inverse transfer) by nullifying magnetic tension. This suppression leaves such structures elongated and confined to scales comparable to the Larmor radius of the particles. The presence of a magnetic guide field of sufficient strength, or a greater scale separation between the initial size of the magnetic structures and the Larmor radius, restores the system's ability to inverse transfer magnetic energy. These results reveal that inverse energy transfer in collisionless plasmas is not guaranteed, but instead sensitively depends on magnetization. In the astrophysical context, this identifies a kinetic mechanism by which Weibel-generated seed fields may fail to merge consistently, potentially limiting their role in cosmic magnetogenesis.
- [3] arXiv:2510.01977 [中文pdf, pdf, html, 其他]
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标题： 用机器学习生成的初始条件加速动力学等离子体模拟标题： Accelerating kinetic plasma simulations with machine learning generated initial conditions主题： 等离子体物理 (physics.plasm-ph) ; 计算物理 (physics.comp-ph)
计算机辅助工程多时间尺度等离子体系统，这些系统表现出准稳态解，由于需要大量时间步才能达到收敛，因此具有挑战性。 结合机器学习技术与传统第一性原理模拟和高性能计算，为解决这一挑战提供了许多有趣的途径。 我们考虑通过机器学习生成的初始条件加速粒子等离子体模拟。 该方法通过建模与微电子工业相关的电容耦合等离子体放电进行了演示。 三个模型在设备驱动频率和工作压力的参数空间上的模拟数据上进行训练。 这些模型结合了多层感知器、主成分分析和卷积神经网络的元素，以预测最终的时间平均离子密度和速度分布函数的轮廓。 这些数据驱动的初始条件生成器（ICGs）在使用离线程序测量时，将收敛时间平均加快了17.1倍，或在使用在线程序时加快了4.4倍，其中卷积神经网络表现最佳。 本文还概述了一个连续数据驱动模型改进和模拟加速的工作流程，旨在生成足够的数据以实现完整的器件数字孪生。
Computer aided engineering of multi-time-scale plasma systems which exhibit a quasi-steady state solution are challenging due to the large number of time steps required to reach convergence. Machine learning techniques combined with traditional first-principles simulations and high-performance computing offer many interesting pathways towards resolving this challenge. We consider acceleration of kinetic plasma simulations via machine learning generated initial conditions. The approach is demonstrated through modeling of capacitively coupled plasma discharges relevant to the microelectronics industry. Three models are trained on simulations across a parameter space of device driving frequency and operating pressure. The models incorporate elements of a multi-layer perceptron, principal component analysis, and convolutional neural networks to predict the final time-averaged profiles of ion-density and velocity distribution functions. These data-driven initial condition generators (ICGs) provide a mean speedup of 17.1x in convergence time, when measured using an offline procedure, or a 4.4x speedup with an online procedure, with convolutional neural networks leading to the best performance. The paper also outlines a workflow for continuous data-driven model improvement and simulation speedup, with the aim of generating sufficient data for full device digital twins.
- [4] arXiv:2510.02088 [中文pdf, pdf, html, 其他]
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标题： 基于神经网络的运动学米氏偏振测量方法用于纳米尘埃等离子体中的粒子尺寸诊断标题： A neural network approach to kinetic Mie polarimetry for particle size diagnostics in nanodusty plasmas评论： 接受的稿件期刊参考： J. Phys. D：应用物理 56 445202 (2023)主题： 等离子体物理 (physics.plasm-ph)
纳米颗粒尺寸的分析是等离子体技术和尘埃等离子体中的重要任务。 基于米氏理论的光散射技术可以作为非侵入性和原位诊断工具来实现这一目的。 然而，标准的反演方法需要用户具备专业知识。 为了解决这个问题，我们引入了一个执行相同任务的神经网络。 我们讨论了如何建立和训练该网络，以分析等离子体生长的非晶碳纳米颗粒（a:C-H）的尺寸，其折射率n的实部在1.4-2.2之间，虚部在0.04i-0.1i之间，半径可达几百纳米，具体取决于使用的波长。 该诊断方法是动力学的，这意味着粒子由于生长或刻蚀需要改变尺寸。 还进行了不确定性分析以及与实验数据的测试。 我们的神经网络所得结果与先前拟合算法的结果一致，同时提供了更高的方法稳定性。 该模型在计算速度和自动化方面也具有显著优势。
The analysis of the size of nanoparticles is an essential task in plasma technology and dusty plasmas. Light scattering techniques, based on Mie theory, can be used as a non-invasive and in-situ diagnostic tool for this purpose. However, the standard back-calculation methods require expertise from the user. To address this, we introduce a neural network that performs the same task. We discuss how we set up and trained the network to analyze the size of plasma-grown amorphous carbon nanoparticles (a:C-H) with a refractive index n in the range of real(n) = 1.4-2.2 and imag(n) = 0.04i-0.1i and a radius of up to several hundred nanometers, depending on the used wavelength. The diagnostic approach is kinetic, which means that the particles need to change in size due to growth or etching. An uncertainty analysis as well as a test with experimental data are presented. Our neural network achieves results that agree with those of prior fitting algorithms while offering higher methodical stability. The model also holds a major advantage in terms of computing speed and automation.
新提交 (展示 4 之 4 条目 )
- [5] arXiv:2510.01875 (交叉列表自 cond-mat.mtrl-sci) [中文pdf, pdf, html, 其他]
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标题： 增强时变密度泛函理论计算动态响应性质的效率标题： Enhancing the Efficiency of Time-Dependent Density Functional Theory Calculations of Dynamic Response PropertiesZhandos A. Moldabekov, Sebastian Schwalbe, Uwe Hernandez Acosta, Thomas Gawne, Jan Vorberger, Michele Pavanello, Tobias Dornheim主题： 材料科学 (cond-mat.mtrl-sci) ; 化学物理 (physics.chem-ph) ; 计算物理 (physics.comp-ph) ; 等离子体物理 (physics.plasm-ph)
X射线汤姆逊散射（XRTS）是诊断极端条件下材料性质的重要技术，例如高压和强激光加热。 时间依赖密度泛函理论（TDDFT）是建模XRTS谱以及一系列其他动态材料性质最准确的可用从头算方法之一。 然而，强烈的热激发，以及需要考虑温度和密度的变化以及探测器的有限尺寸，显著增加了与常规条件相比的TDDFT模拟的计算成本。 在本工作中，我们提出了一种广泛适用的方法，用于优化和提高TDDFT计算的效率。 我们的方法基于动态结构因子与虚时密度-密度关联函数之间的一一映射，这在费曼的量子多体理论路径积分公式中自然出现。 具体而言，我们将虚时域中的严格收敛测试与基于约束的噪声衰减技术相结合，以在不引入任何显著偏差的情况下提高TDDFT建模的效率。 因此，我们可以报告出高达一个数量级的速度提升，从而可能为建模极端条件下物质的单个XRTS测量节省数百万CPU小时。
X-ray Thomson scattering (XRTS) constitutes an essential technique for diagnosing material properties under extreme conditions, such as high pressures and intense laser heating. Time-dependent density functional theory (TDDFT) is one of the most accurate available ab initio methods for modeling XRTS spectra, as well as a host of other dynamic material properties. However, strong thermal excitations, along with the need to account for variations in temperature and density as well as the finite size of the detector significantly increase the computational cost of TDDFT simulations compared to ambient conditions. In this work, we present a broadly applicable method for optimizing and enhancing the efficiency of TDDFT calculations. Our approach is based on a one-to-one mapping between the dynamic structure factor and the imaginary time density--density correlation function, which naturally emerges in Feynman's path integral formulation of quantum many-body theory. Specifically, we combine rigorous convergence tests in the imaginary time domain with a constraints-based noise attenuation technique to improve the efficiency of TDDFT modeling without the introduction of any significant bias. As a result, we can report a speed-up by up to an order of magnitude, thus potentially saving millions of CPU hours for modeling a single XRTS measurement of matter under extreme conditions.
- [6] arXiv:2510.01957 (交叉列表自 math.DS) [中文pdf, pdf, html, 其他]
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标题： 可积磁场磁面所包围体积的公式数值测试标题： Numerical tests of formulae for volume enclosed by flux surfaces of integrable magnetic fields评论： 关键词：磁场，磁力线，体积主题： 动力系统 (math.DS) ; 等离子体物理 (physics.plasm-ph)
对体积公式的数值测试被提出，以高效计算可积三维向量场之间由磁面所包围的体积，这些向量场具有各种对称性程度。 在这一过程中，提出并测试了一个新案例。
Numerical tests of volume formulae are presented to compute efficiently the volume enclosed between flux surfaces for integrable 3D vector fields with various degrees of symmetry. In the process, a new case is proposed and tested.
- [7] arXiv:2510.02301 (交叉列表自 astro-ph.HE) [中文pdf, pdf, html, 其他]
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标题： 射电识别的超大质量黑洞双星候选体中的相对论喷流和风标题： Relativistic Jets and Winds in Radio-Identified Supermassive Black Hole Binary CandidatesAndrew G. Sullivan, Roger D. Blandford, Anna Synani, Philipe V. de la Parra, No√©mie Globus, Mitchell C. Begelman, Anthony C.S. Readhead评论： 13页，8图，已提交至天体物理杂志主题： 高能天体物理现象 (astro-ph.HE) ; 星系的天体物理学 (astro-ph.GA) ; 等离子体物理 (physics.plasm-ph)
超大质量黑洞双星系统（SMBHBs）被认为会发出最近发现的nHz引力波背景；然而，到目前为止，还没有任何一个单独的nHz源被确认。 在欧文斯谷射电天文台进行的长期射电监测已经发现了两个潜在的SMBHB候选体：blazars PKS 2131-021和PKS J0805-0111。 这些源在电磁谱上表现出周期性的流量密度变化，表明存在一个良好的时钟。 为了解释这种辐射，我们提出了一种可推广的喷流模型，其中一种轻微相对论性风形成了向外移动的螺旋通道，超相对论性喷流沿此通道传播。 从喷流中观测到的流量变化主要是由于像差效应。 较低频率的辐射出现在更大的半径处，因此其变化相应地被延迟，如观察到的那样。 我们的模型再现了这两个源的主要可观测特征，并且可以在发现其他源时应用。 我们对射电偏振、直接成像和发射线变化进行了预测，这些可以利用未来的观测进行测试。 我们的结果激发了对喷流SMBHB系统的未来数值模拟，并对blazar喷流的供能、结构和演化具有重要意义。
Supermassive black hole binary systems (SMBHBs) are thought to emit the recently discovered nHz gravitational wave background; however, not a single individual nHz source has been confirmed to date. Long-term radio-monitoring at the Owens Valley Radio Observatory has revealed two potential SMBHB candidates: blazars PKS 2131-021 and PKS J0805-0111. These sources show periodic flux density variations across the electromagnetic spectrum, signaling the presence of a good clock. To explain the emission, we propose a generalizable jet model, where a mildly relativistic wind creates an outward-moving helical channel, along which the ultra-relativistic jet propagates. The observed flux variation from the jet is mostly due to aberration. The emission at lower frequency arises at larger radius and its variation is consequently delayed, as observed. Our model reproduces the main observable features of both sources and can be applied to other sources as they are discovered. We make predictions for radio polarization, direct imaging, and emission line variation, which can be tested with forthcoming observations. Our results motivate future numerical simulations of jetted SMBHB systems and have implications for the fueling, structure, and evolution of blazar jets.
交叉提交 (展示 3 之 3 条目 )
- [8] arXiv:2510.00388 (替换) [中文pdf, pdf, html, 其他]
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标题： 对完全电离和部分电离氢共存状态的电子和离子结构的研究，使用中性伪原子方法以及电子子系统的经典映射标题： A study of the electronic and ionic structure, for co-existing states of fully and partially ionized hydrogen, using the neutral pseudo-atom method as well as a classical map for the electron subsystem评论： 提交至专刊：等离子体物理贡献，Bonitz 荣誉专辑主题： 等离子体物理 (physics.plasm-ph) ; 统计力学 (cond-mat.stat-mech)
教授迈克尔·博尼茨及其合作者在使用{\it 从头计算}模拟研究均匀电子流体和电子-质子流体（即氢气）方面做出了开创性的贡献。 这些研究为天体物理学以及高能量密度物理提供了重要的输入。 这一点在他的荣誉文集中有所体现。 当温度与费米能级$E_F$相当时，电子-质子系统在理论建模上变得特别困难，此时氢气达到温密物质（WDM）状态。 在本研究中，我们简要回顾了研究WDM系统的可用理论方法，并利用中性伪原子（NPA）方法以及用于量子电子的经典映射来研究完全电离和部分电离的氢气。 结果表明，在许多情况下，{\it 两者}完全电离和部分电离状态可以在{\it 相同的密度和温度}独立存在。 最近的研究使用路径积分蒙特卡洛方法以及$N$原子密度泛函理论（DFT）模拟，提供了包括进入X射线汤姆逊散射和其他诊断解释的电子-电子结构因子$S_{ee}(k)$的重要结构数据。 我们展示了可以使用经典映射方案对完全电离等离子体进行快速且低成本的评估，并且更普遍地使用单原子（平均原子）DFT方法对部分电离系统进行评估，精度足够。
Prof. Michael Bonitz and his collaborators have made seminal contributions to the study of the uniform electron fluid and the electron-proton fluid, viz., hydrogen, in using {\it ab initio} simulations. These studies provide essential inputs to astrophysics as well as high-energy density physics. This is reflected in the contributions to this festshrift in his honour. The electron-proton system becomes particularly difficult for theoretical modeling when the temperature becomes comparable to the Fermi energy $E_F$, when the warm-dense matter (WDM) state of hydrogen is reached. In this study we briefly review the theoretical methods available for the study of WDM systems, and use the neutral-pseudo atom (NPA) method, and a classical map for quantum electrons to study fully and partially ionized hydrogen. It is shown that {\it both} fully and partially ionized states can independently exist at the {\it same density and temperature} in many cases. Recent studies using path-integral Monte Carlo methods, and $N$-atom Density Functional Theory (DFT) simulations have provided essential structure data including the electron-electron structure factor $S_{ee}(k)$ that enters into interpretation of X-ray Thomson scattering and other diagnostics. We show that these structure data can be rapidly and inexpensively evaluated, with sufficient accuracy, using classical-map schemes for fully ionized plasmas, and more generally, using one-atom (average-atom) DFT methods for partially ionized systems.