等离子体物理

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新提交 (展示 4 之 4 条目 )

[1] arXiv:2508.03152 [中文pdf, pdf, html, 其他]

标题： 通过调整激光等离子体参数控制交叉束能量传输 显示英文标题

标题： Control of cross-beam energy transfer through laser-plasma parameter adjustment

Yilin Xu, Yao Zhao, Hongwei Yin, Zhuwen Lin, Yan Yin, Liang Hao, Yaozhi Yi, Hongyu Zhou, Jinlong Jiao, Anle Lei

评论： 20页，24图

主题： 等离子体物理 (physics.plasm-ph)

通过分析理论和二维模拟，研究了两束激光之间的交叉束能量转移（CBET），特别关注其在不同激光等离子体条件下从几百皮秒到一纳秒时间尺度上的线性和非线性演化。 基于由两束激光驱动的受激布里渊散射的色散关系，我们得到了CBET发生的激光频率差范围。 在非线性区域，离子声波（IAW）的高次谐波导致高激光强度下的饱和水平降低（$I\gtrsim 10^{15}\,\mathrm{W/cm^2}$）。 谐波IAW的波破裂导致CBET的第二次增长和最终饱和。 在低强度下，线性饱和水平随时间缓慢变化。 与高斯光束相比，带有斑点的平滑激光可以通过减少有效重叠区域来减轻CBET的饱和水平。 由于离子捕获引起的IAW频率降低，最大能量转移出现在略小于线性匹配条件的频率差处。 我们发现非线性行为对激光强度、频率差、电子密度和离子温度敏感。 总能量转移速率随着激光强度近似线性增加，强调了其在CBET控制中的关键作用。 显示英文摘要

Cross-beam energy transfer (CBET) between two lasers is investigated through both analytical theory and two-dimensional simulations, with particular attention to its linear and nonlinear evolution under various laser-plasma conditions over timescales from several hundred picoseconds to one nanosecond. Based on the dispersion relation of stimulated Brillouin scattering driven by two laser beams, we obtain a laser frequency difference range within which CBET occurs. In the nonlinear regime, high harmonic of ion acoustic wave (IAW) leads to the reduction of saturation level at high laser intensities ($I\gtrsim 10^{15}\,\mathrm{W/cm^2}$). The wave breaking of harmonic IAW causes the second growth and final saturation of CBET. At low intensities, the linear saturation level slowly varies over time. Compared to Gaussian beams, smoothed lasers with speckles can mitigate CBET saturation level by reducing the effective overlap region. The maximum energy transfer is found at a frequency difference slightly smaller than the linear matching condition due to the reduction of IAW frequency induced by ion trapping. We find that the nonlinear behavior is sensitive to laser intensity, frequency difference, electron density, and ion temperature. The total energy transfer rate increases approximately linearly with laser intensity, underscoring its critical role in CBET control.

[2] arXiv:2508.03309 [中文pdf, pdf, 其他]

标题： 空气中10 kHz激光丝诱导等离子体的光致发光光谱表征 显示英文标题

标题： Characterization of a laser filament-induced plasma in air at 10 kHz using optical emission spectroscopy

Malte C. Schroeder, Robin Löscher, Nikita Bibinov, Ihor Korolov, Peter Awakowicz, Thomas Mussenbrock, Clara J. Saraceno

主题： 等离子体物理 (physics.plasm-ph) ; 光学 (physics.optics)

高功率基于Yb的超快激光放大系统日益普及，使得在高重复率大于1 kHz的情况下实现空气丝化成为可能。 在这个新领域中，不能排除积累效应，因此表征等离子体参数和余辉等离子体化学动力学变得越来越重要。 在本工作中，我们使用光学发射光谱测量大气空气激光丝在高平均功率飞秒激光和高重复率10 kHz下的气体温度和电子温度、物种特异性衰减时间以及电子密度的纳秒动态。 氮气光致发光背后的分子激发机制来源于所研究发射带的振动分布和时间行为。 该诊断技术为表征高重复率丝状物引起的等离子体尾波提供了补充但更全面的测量方法，与光学探测方案形成互补。 显示英文摘要

The increasing availability of high-power Yb-based ultrafast laser-amplifier systems has opened the possibility of air filamentation at high repetition rates >1 kHz. In this new regime, accumulation effects cannot be ruled out, therefore, characterizing the plasma parameters and afterglow plasma-chemical kinetics becomes increasingly relevant. In this work, we use optical emission spectroscopy to measure nanosecond dynamics of gas temperature and electron temperature, species-specific decay times, and electron density of an atmospheric air laser filament produced by high average power femtosecond laser at a high repetition rate of 10 kHz. The molecular excitation mechanisms behind the nitrogen photoemissions are derived from vibrational distributions and temporal behavior of the studied emission bands. The presented diagnostic technique offers a complementary but more holistic measurement approach to optical probe schemes to characterize the laser-filament-induced plasma wake for high repetition rate filaments.

[3] arXiv:2508.03478 [中文pdf, pdf, html, 其他]

标题： 定态幂律解的动能阿尔芬湍流 显示英文标题

标题： Stationary Power-Law Solutions of Kinetic-Alfvénic Turbulence

Kexun Shen, Zhiwen Cheng, Zhiyong Qiu

评论： 13页，8图

主题： 等离子体物理 (physics.plasm-ph) ; 空间物理 (physics.space-ph)

基于回旋动力学理论框架的弱动力学阿尔芬湍流的波动力学描述被提出。 通过共振三波相互作用描述动力学阿尔芬波谱级联的波动力学方程被推导出来，并在长波长极限和短波长极限下，利用扎哈罗夫变换分别得到了反向传播和同向传播情况下的稳态谱。 识别了稳态解的级联方向，并通过求解波动力学方程的数值解进一步验证了它们的存在性。 简要讨论了这些预测与太阳风湍流和螺旋动力学阿尔芬湍流的相关性。 显示英文摘要

The wave-kinetic description of weak kinetic-Alfv\'{e}nic turbulence based on the gyrokinetic theoretical framework is proposed. The wave kinetic equation describing kinetic Alfv\'{e}n wave spectral cascading via resonant three-wave interactions is derived, and the stationary spectra are analytically obtained using the Zakharov transformation in both the long-wavelength limit and the short-wavelength limit, for both counter-propagating and co-propagating cases. The cascade directions of stationary solutions are identified and their existence is further verified by numerical solution of the wave kinetic equation. A brief discussion on the relevance of such predictions to the solar wind turbulence and helical kinetic-Alfv\'{e}nic turbulence is presented.

[4] arXiv:2508.03561 [中文pdf, pdf, html, 其他]

标题： 托卡马克中电流上升和下降的简单模型 显示英文标题

标题： A Simple Model of Current Ramp-Up and Ramp-Down in Tokamaks

R. Fitzpatrick

主题： 等离子体物理 (physics.plasm-ph)

一种描述托卡马克等离子体环向电流上升和下降的简单模型被开发出来。 发现法拉第电磁感应定律限制了电流安全上升或下降的速度。 估计JET、SPARC和ITER托卡马克的最小安全上升/下降时间分别为4.2秒、2.0秒和14.7秒。 JET的上升速率与运行经验一致。 SPARC和ITER的最小安全上升速率小于各自设计中的上升速率。 因此，没有迹象表明设计上升速率不可行，正如最近在arXiv:2507.05456 (2025)中所建议的那样。 发现SPARC和ITER中感应电场与Connor-Hastie场的典型比值小于JET中的比值。 因此，JET托卡马克在电流上升过程中成功运行且未遇到奔逃电子问题的事实表明，未来的SPARC和ITER托卡马克也应能够避免此类问题。 显示英文摘要

A simple model of the ramp-up and ramp-down of the toroidal current in a tokamak plasma is developed. Faraday's law of electric induction is found to limit how rapidly the current can be safety ramped up or down. It is estimated that the minimum safe ramp-up/down times for the JET, SPARC, and ITER tokamaks are 4.2, 2.0, and 14.7 seconds, respectively. The JET ramp rate is in accordance with operational experience. The SPARC and ITER minimum safe ramp rates are less than the ramp rates in the respective designs. Hence, there is no indication that the design ramp rates are infeasible, as was recently suggested in arXiv:2507.05456 (2025). The typical ratios of the inductive electric field to the Connor-Hastie field in SPARC and ITER are found to be less than those in JET. Thus, the fact that the JET tokamak was able to operate successfully without encountering runaway electron problems during current ramps suggests that the future SPARC and ITER tokamaks should also be able to avoid such problems.

交叉提交 (展示 1 之 1 条目 )

[5] arXiv:2508.03443 (交叉列表自 astro-ph.SR) [中文pdf, pdf, html, 其他]

标题： 快模可压缩湍流中的能量级联与阻尼 显示英文标题

标题： Energy Cascade and Damping in Fast-Mode Compressible Turbulence

Chuanpeng Hou, Huirong Yan, Siqi Zhao, Parth Pavaskar

评论： 4张图

主题： 太阳与恒星天体物理学 (astro-ph.SR) ; 等离子体物理 (physics.plasm-ph)

这封信提出了对快模可压缩湍流的混合和全动能粒子-网格模拟。磁流体动力学（MHD）尺度上的湍流阻尼紧密遵循线性穿越时间阻尼理论。尽管相位急剧变化，湍流仍维持强大的跨尺度能量级联。这些发现解决了关于经典波理论在强非线性区域有效性的一个长期问题，并推翻了波陡化会破坏可压缩湍流级联的普遍假设，从而提供了更完整的MHD湍流图景。 显示英文摘要

This letter presents hybrid and fully kinetic particle-in-cell simulations of fast-mode compressible turbulence. Turbulence damping at magnetohydrodynamic (MHD) scales closely follows linear transit-time damping theory. Despite strong phase steepening, turbulence sustains robust cross-scale energy cascading. These findings resolve the long-standing question about the validity of classical wave theories in strongly nonlinear regimes and overturn the common presumption that wave steepening disrupts compressible turbulence cascade, thereby providing a more complete picture of MHD turbulence.

替换提交 (展示 5 之 5 条目 )

[6] arXiv:2412.03112 (替换) [中文pdf, pdf, html, 其他]

标题： 非线性MHD对ASDEX升级装置破碎 pellet 注入的模拟 显示英文标题

标题： Non-linear MHD modelling of shattered pellet injection in ASDEX Upgrade

W. Tang, M. Hoelzl, M. Lehnen, D. Hu, F. J. Artola, P. Halldestam, P. Heinrich, S. Jachmich, E. Nardon, G. Papp, A. Patel, the ASDEX Upgrade Team, the EUROfusion Tokamak Exploitation Team, the JOREK Team

主题： 等离子体物理 (physics.plasm-ph)

破碎弹丸注入（SPI）被选为ITER的中断缓解系统，由于其更深的穿透、预期的吸收效率和及时的材料输送。 本文描述了在ASDEX升级托卡马克中使用JOREK代码对掺杂氖的氘弹丸SPI进行非线性磁流体动力学（MHD）模拟，以测试不同注入参数的缓解效率。 这些模拟作为流体模拟执行，同时使用额外的标记粒子基于OpenADAS原子数据演化杂质的电荷态分布和辐射特性，即使用碰撞-辐射模型。 进行了0 - 10%的氖浓度扫描。 数值结果表明，热淬火（TQ）分为两个阶段。 在第一阶段，大约一半的热能突然损失，主要通过随机场中的对流和传导传输。 这一阶段相对独立于氖浓度。 在第二阶段，大部分剩余热能损失，辐射起主导作用。 在纯氘注入的情况下，这一阶段可能根本不会发生。 对于低氖浓度弹丸（$\leq 0.12\%$），弹丸中总材料的较大比例（$\sim $20%）被等离子体吸收，因为等离子体的完全热崩溃发生得比高氖浓度情况更晚。 然而，吸收的氖原子总数随着氖浓度的增加而增加。 然后数值研究了碎片大小和穿透速度的影响，显示较慢和较小的碎片促进边缘冷却和冷前沿的形成。 较快的碎片由于更快到达更热的等离子体区域，导致较短的TQ持续时间和更高的吸收率。 显示英文摘要

Shattered pellet injection (SPI) is selected for the disruption mitigation system in ITER, due to deeper penetration, expected assimilation efficiency and prompt material delivery. This article describes non-linear magnetohydrodynamic (MHD) simulations of SPI in the ASDEX Upgrade tokamak to test the mitigation efficiency of different injection parameters for neon-doped deuterium pellets using the JOREK code. The simulations are executed as fluid simulations, while additional marker particles are used to evolve the charge state distribution and radiation property of impurities based on OpenADAS atomic data, i.e., a collisional-radiative model is used. Neon fraction scans between 0 - 10% are performed. Numerical results show that the thermal quench (TQ) occurs in two stages. In the first stage, approximately half of the thermal energy is abruptly lost, primarily through convective and conductive transport in the stochastic fields. This stage is relatively independent of the neon fraction. In the second stage, where the majority of the remaining thermal energy is lost, radiation plays a dominant role. In case of pure deuterium injection, this second stage may not occur at all. A larger fraction ($\sim $20%) of the total material in the pellet is assimilated in the plasma for low neon fraction pellets ($\leq 0.12\%$) due to the full thermal collapse of the plasma occurring later than in high neon fraction scenarios. Nevertheless, the total number of assimilated neon atoms increases with increasing neon fraction. The effects of fragment size and penetration speed are then numerically studied, showing that slower and smaller fragments promote edge cooling and the formation of a cold front. Faster fragments result in shorter TQ duration and higher assimilation as they reach the hotter plasma regions quicker.

[7] arXiv:2504.07311 (替换) [中文pdf, pdf, html, 其他]

标题： 二维不可压缩无耗散霍尔磁流体动力学中的磁X点崩溃情景 显示英文标题

标题： Scenarios for magnetic X-point collapse in 2D incompressible dissipationless Hall magnetohydrodynamics

Alain J. Brizard

评论： 26页，16图

主题： 等离子体物理 (physics.plasm-ph) ; 数学物理 (math-ph)

二维不可压缩无耗散霍尔磁流体动力学（HMHD）的方程，将流体速度${\bf V} = \wh{\sf z}\btimes\nabla\phi + V_{z}\,\wh{\sf z}$与磁场${\bf B} = \nabla\psi\btimes\wh{\sf z} + B_{z}\,\wh{\sf z}$耦合，已知可以支持表现出有限时间奇点的解，这些奇点与平面$(B_{x} = \partial\psi/\partial y, B_{y} = -\,\partial\psi/\partial x)$中的磁X点坍缩有关。 在这里，通过采用四个HMHD场$(\phi,\psi,V_{z},B_{z})$的二维自相似模型，保留有限电子惯性，我们得到了五个耦合的常微分方程，这些方程基于粒子在四次势中的轨道分类，用雅可比椭圆函数求解。 当将这些解析解与数值解进行比较时，发现有很好的一致性，包括磁X点坍缩的精确时间。 显示英文摘要

The equations of 2D incompressible dissipationless Hall magnetohydrodynamics (HMHD), which couple the fluid velocity ${\bf V} = \wh{\sf z}\btimes\nabla\phi + V_{z}\,\wh{\sf z}$ with the magnetic field ${\bf B} = \nabla\psi\btimes\wh{\sf z} + B_{z}\,\wh{\sf z}$, are known to support solutions that exhibit finite-time singularities associated with magnetic X-point collapse in the plane $(B_{x} = \partial\psi/\partial y, B_{y} = -\,\partial\psi/\partial x)$. Here, by adopting a 2D self-similar model for the four HMHD fields $(\phi,\psi,V_{z},B_{z})$, which retains finite electron inertia, we obtain five coupled ordinary differential equations that are solved in terms of the Jacobi elliptic functions based on an orbital classification associated with particle motion in a quartic potential. Excellent agreement is found when these analytical solutions are compared with numerical solutions, including the precise time of a magnetic X-point collapse.

[8] arXiv:2507.08156 (替换) [中文pdf, pdf, html, 其他]

标题： 保持体积的蜂窝线介质变形实现了宽频等离子频率可调性 显示英文标题

标题： Volume-Preserving Deformation of Honeycomb Wire Media Enables Broad Plasma Frequency Tunability

Denis Sakhno, Jim A. Enriquez, Pavel A. Belov

主题： 等离子体物理 (physics.plasm-ph) ; 材料科学 (cond-mat.mtrl-sci)

我们通过机械变形由平行金属线在蜂窝结构节点上排列的晶格，展示了等离子体频率在导线介质中的可调性。 数值模拟预测最高可达78%的可调性，一个概念验证实验确认了64%的可调性。 显示英文摘要

We demonstrate tunability of the plasma frequency in a wire medium by mechanically deforming a lattice of parallel metallic wires arranged at the nodes of a honeycomb structure. Numerical simulations predict up to 78% tunability and a proof-of-concept experiment confirms 64%.

[9] arXiv:2508.00720 (替换) [中文pdf, pdf, html, 其他]

标题： 非均匀磁化圆柱等离子体边界处拓扑保护边缘模的连续阻尼 显示英文标题

标题： Continuum damping of topologically-protected edge modes at the boundary of non-uniformly magnetized cylindrical plasmas

Roopendra Singh Rajawat, Gennady Shvets

评论： 10页和4图

主题： 等离子体物理 (physics.plasm-ph)

我们提出了一种对最近发现的无碰撞阻尼但拓扑保护的表面等离子体波（TSPWs）的扩展，从简化的板状几何结构到圆柱形等离子体-真空界面。 这些模式的一个显著特征是它们出现在电子回旋频率之上，其无碰撞阻尼来自于与局部在平滑等离子体-真空过渡层内的上混合模式连续体的共振耦合。 我们展示了在磁化等离子体圆柱边界处TSPWs的时间和空间衰减。 此外，我们表明在存在非均匀磁场的情况下，TSPW表现出平滑且连续的转变，突显了其在磁不均匀性下的拓扑鲁棒性。 显示英文摘要

We present an extension of recently discovered collisionlessly damped yet topologically protected surface plasma waves (TSPWs), from a simplified slab geometry to a cylindrical plasma-vacuum interface. A distinctive feature of these modes-emerging above the electron cyclotron frequency-is their collisionless damping, which arises from resonant coupling to a continuum of upper-hybrid modes localized within a smooth plasma-vacuum transition layer. We demonstrate both temporal and spatial damping of TSPWs at the boundary of a cylindrical magnetized plasma. Furthermore, we show that in the presence of a non-uniform magnetic field, the TSPW exhibits a smooth and continuous transition, highlighting its topological robustness under magnetic inhomogeneity.

[10] arXiv:2312.03984 (替换) [中文pdf, pdf, html, 其他]

标题： 控制可压缩模态：体积粘度和湍流发电机 显示英文标题

标题： Taking control of compressible modes: bulk viscosity and the turbulent dynamo

James R. Beattie, Christoph Federrath, Neco Kriel, Justin Kin Jun Hew, Amitava Bhattacharjee

评论： 31页，21图，已被MNRAS接收

主题： 星系的天体物理学 (astro-ph.GA) ; 高能天体物理现象 (astro-ph.HE) ; 等离子体物理 (physics.plasm-ph)

许多多原子天体物理等离子体是可压缩的，并且处于化学和热力学非平衡状态，通过分子组成的内部自由度引入了体积粘度，直接影响可压缩模式的衰减，$\mathbf{v}_{\parallel}(\mathbf{k})$。 这对于星际介质中的小尺度湍流发电机过程尤其重要，这些过程已知对压缩效应非常敏感。 为了控制$\mathbf{v}_{\parallel}(\mathbf{k})$的粘性特性，我们进行了跨音速、粘性电阻发电机模拟，并加入了额外的体积粘度$\nu_{\rm bulk}$，推导出一个新的$\nu_{\rm bulk}$雷诺数$\rm{Re}_{\rm bulk}$以及粘性普朗特数$\rm{P}\nu \equiv \rm{Re}_{\rm bulk} / \rm{Re}_{\rm shear}$，其中$\rm{Re}_{\rm shear}$是剪切粘度雷诺数。 我们通过$\nabla\otimes\mathbf{v}$的正交张量分解，推导出一种将$E_{\rm mag}$增长率分解为不可压缩和可压缩项的框架，其中$\mathbf{v}$是流体速度。 我们发现$\mathbf{v}_{\parallel}(\mathbf{k})$起着双重作用，既促进又抑制$E_{\rm mag}$，并且即使在可压缩发电机中，场线拉伸也是增长的主要驱动因素。 在没有$\nu_{\rm bulk}$（$\rm{P}\nu \to \infty$）的情况下，$\mathbf{v}_{\parallel}(\mathbf{k})$在小尺度上堆积，形成谱瓶颈，这在$\rm{P}\nu \approx 1$时消失。 （摘要）。 我们强调进一步理解$\nu_{\rm bulk}$在可压缩天体物理等离子体中的重要性，我们认为其强度可能与冷星际介质中的剪切粘度相当，并指出没有体积粘度的可压缩直接数值模拟存在未解析的可压缩模式耗散尺度。 显示英文摘要

Many polyatomic astrophysical plasmas are compressible and out of chemical and thermal equilibrium, introducing a bulk viscosity into the plasma via the internal degrees of freedom of the molecular composition, directly impacting the decay of compressible modes, $\mathbf{v}_{\parallel}(\mathbf{k})$. This is especially important for small-scale, turbulent dynamo processes in the interstellar medium, which are known to be sensitive to the effects of compression. To control the viscous properties of $\mathbf{v}_{\parallel}(\mathbf{k})$, we perform trans-sonic, visco-resistive dynamo simulations with additional bulk viscosity $\nu_{\rm bulk}$, deriving a new $\nu_{\rm bulk}$ Reynolds number $\rm{Re}_{\rm bulk}$, and viscous Prandtl number $\rm{P}\nu \equiv \rm{Re}_{\rm bulk} / \rm{Re}_{\rm shear}$, where $\rm{Re}_{\rm shear}$ is the shear viscosity Reynolds number. We derive a framework for decomposing $E_{\rm mag}$ growth rates into incompressible and compressible terms via orthogonal tensor decompositions of $\nabla\otimes\mathbf{v}$, where $\mathbf{v}$ is the fluid velocity. We find that $\mathbf{v}_{\parallel}(\mathbf{k})$ play a dual role, growing and decaying $E_{\rm mag}$, and that field-line stretching is the main driver of growth, even in compressible dynamos. In the absence of $\nu_{\rm bulk}$ ($\rm{P}\nu \to \infty$), $\mathbf{v}_{\parallel}(\mathbf{k})$ pile up on small-scales, creating a spectral bottleneck, which disappears for $\rm{P}\nu \approx 1$. (abridged). We emphasize the importance of further understanding the role of $\nu_{\rm bulk}$ in compressible astrophysical plasmas, which we estimate could be as strong as the shear viscosity in the cold ISM, and highlight that compressible direct numerical simulations without bulk viscosity have unresolved compressible mode dissipation scales.