Plasma Physics

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New submissions (showing 2 of 2 entries )

[1] arXiv:2509.20594 [cn-pdf, pdf, html, other]

Title: Anderson self-localization of light in pair plasmas Show Chinese title

Title: 安德森光在双等离子体中的自定位

Maxim Lyutikov (Purdue University), Victor Gurarie (University of Colorado)

Subjects: Plasma Physics (physics.plasm-ph) ; High Energy Astrophysical Phenomena (astro-ph.HE) ; Disordered Systems and Neural Networks (cond-mat.dis-nn)

We demonstrate that in pair plasma weakly nonlinear electromagnetic waves, $a_0 \leq 1$, experience Anderson self-localization. The beat between the driver and a back-scattered wave creates random, charge-neutral, large density fluctuations $\delta \rho/\rho \gg 1$, and corresponding random fluctuations of the dielectric permittivity $\epsilon$. Propagating in quasi-1D, waves in a medium with spatially random, time-varying, self-created fluctuations of dielectric permeability experience localization. Anderson self-localization of light leads to (i) reflection of EM waves by the under-dense pair plasma; (ii) a wave already present inside the plasma separates into bright trapped pockets and dark regions. Mild initial thermal spread restores wave propagation by suppressing the seeds of parametrically unstable density fluctuations. A circularly polarized driver produces linearly polarized structures, with position angle varying randomly between the bright pulses. We discuss possible applications to astrophysical Fast Radio Bursts. Show Chinese abstract

我们证明在等离子体中弱非线性电磁波，$a_0 \leq 1$，经历安德森自局域化。驱动波与反向散射波的拍频产生随机、电荷中性、大密度涨落$\delta \rho/\rho \gg 1$，以及相应的介电常数$\epsilon$的随机涨落。在具有空间随机、时间变化、自产生的介电渗透率涨落的准一维介质中传播的波会发生局域化。光的安德森自局域化导致（i）由稀薄等离子体对电磁波的反射；（ii）等离子体内已有的波分离成明亮的束缚区域和暗区。轻微的初始热扩散通过抑制参数不稳定密度涨落的种子来恢复波的传播。圆偏振驱动波产生线偏振结构，其位置角在明亮脉冲之间随机变化。我们讨论了其在天体物理快速射电暴中的可能应用。

[2] arXiv:2509.21048 [cn-pdf, pdf, html, other]

Title: Reply to "Comments to Marvel Fusions Mixed Fuels Reactor Concept" Show Chinese title

Title: 回复“对漫威融合混合燃料反应堆概念的评论”

Hartmut Ruhl, Georg Korn

Comments: Reply to arXiv:2312.13429

Subjects: Plasma Physics (physics.plasm-ph)

In "arXiv:2312.13429" Lackner et al. use standard methods to decide if it is possible to ignite mixed fuels. They correctly identify that the increased radiation losses make ignition significantly more challenging than for pure DT fuels, since this leads to higher ignition temperatures. Further, they conclude that at those temperatures the reduced electronic $\alpha$-stopping makes ignition impossible. We show that this conclusion is not correct. The model used for $\alpha$-stopping by Lackner et al. is only approximately correct for low temperatures and hydrogen isotopes. By extending the $\alpha$-stopping model to include ionic $\alpha$-stopping we show in \cite{ruhlkornarXiv5} that the contribution of ionic $\alpha$-particle stopping cannot be neglected. The ionic $\alpha$-stopping together with the neutron stopping, which is also neglected by Lackner et al., lead to elevated ion temperatures implying $kT_i > kT_e$. Those three effects combined lead us to the conclusion, that ignition of mixed fuels is indeed possible with far reaching implications, contrary to the analysis by Lackner. Show Chinese abstract

在“arXiv:2312.13429”中，Lackner等人使用标准方法来判断混合燃料是否可以点燃。他们正确地指出，增加的辐射损失使得点燃比纯DT燃料要困难得多，因为这会导致更高的点火温度。此外，他们得出结论，在这些温度下，电子$\alpha$-停止作用的减少使得点燃成为不可能。我们表明这个结论是不正确的。Lackner等人用于$\alpha$-停止作用的模型仅在低温和氢同位素情况下大致正确。通过将$\alpha$-停止模型扩展以包括离子$\alpha$-停止，我们在\cite{ruhlkornarXiv5}中表明，离子$\alpha$-粒子停止的作用不能被忽略。 离子$\alpha$停止与中子停止一起，同样被 Lackner 等人忽略，导致离子温度升高，意味着$kT_i > kT_e$。 这三个效应结合使我们得出结论，混合燃料的点火确实是可能的，具有深远的影响，这与 Lackner 的分析相反。

Replacement submissions (showing 3 of 3 entries )

[3] arXiv:2509.20535 (replaced) [cn-pdf, pdf, html, other]

Title: Characterizing Nanoflare Energy and Frequency through Field Line Analysis Show Chinese title

Title: 通过磁力线分析表征纳米耀斑的能量和频率

Shanwlee Sow Mondal, Lars K. S. Daldorff, James A. Klimchuk, Craig D. Johnston

Comments: 24 pages, 24 figures, Accepted for publication in ApJ

Subjects: Solar and Stellar Astrophysics (astro-ph.SR) ; Plasma Physics (physics.plasm-ph)

We present a detailed analysis of a 3D MHD simulation of a subset of the magnetic flux in an active region. The simulation models the generation of nanoflares and response of the plasma to imposed photospheric motions. Our study focuses on characterizing the energy distribution and occurrence frequency of the nanoflares in the simulation that self-consistently heat the corona. This field line based analysis reveals that the nanoflare energy distribution (energy per unit cross sectional area) follows a log-normal profile, where low energy nanoflares are significantly more prevalent than those with high energy. When compared with the plasma cooling time, different energy nanoflares tend to repeat with different frequencies. Low energy nanoflares repeat at high frequencies, while high energy nanoflares repeat at low frequencies. However, the thermal evolution of plasma along individual field lines is governed predominantly by the high energy nanoflares. These findings provide critical insights into the role of small-scale magnetic reconnection events in heating the solar corona. Show Chinese abstract

我们对活动区中一部分磁通量的三维MHD模拟进行了详细分析。 该模拟模型描述了纳米耀斑的产生以及等离子体对施加的光球运动的响应。 我们的研究重点是表征模拟中纳米耀斑的能量分布和发生频率，这些纳米耀斑自洽地加热日冕。 这种基于场线的分析表明，纳米耀斑能量分布（单位横截面积的能量）遵循对数正态分布，其中低能纳米耀斑比高能纳米耀斑显著更常见。 当与等离子体冷却时间比较时，不同能量的纳米耀斑倾向于以不同的频率重复。 低能纳米耀斑以高频重复，而高能纳米耀斑以低频重复。 然而，沿单个场线的等离子体热演化主要由高能纳米耀斑主导。 这些发现为小尺度磁重联事件在加热太阳日冕中的作用提供了关键见解。

[4] arXiv:2509.20654 (replaced) [cn-pdf, pdf, html, other]

Title: Stochastic Heating in the Sub-Alfvénic Solar Wind Show Chinese title

Title: 亚阿尔芬太阳风中的随机加热

Trevor A. Bowen, Tamar Ervin, Alfred Mallet, Benjamin D. G. Chandran, Nikos Sioulas, Philip A. Isenberg, Stuart D. Bale, Jonathan Squire, Kristopher G. Klein, Oreste Pezzi

Subjects: Solar and Stellar Astrophysics (astro-ph.SR) ; Plasma Physics (physics.plasm-ph) ; Space Physics (physics.space-ph)

Collisionless dissipation of turbulence is important for heating plasmas in astrophysical, space physics, and laboratory environments, controlling energy, momentum and particle transport. We analyze Parker Solar Probe observations to understand the collisionless heating of the sub-Alfv\'enic solar wind, which is connected to the solar corona. Our results show that linear resonant heating through parallel-propagating cyclotron waves cannot account for turbulent dissipation in sub-Alfv\'enic region, which observations suggest may dissipate turbulence at distances further from the Sun. Instead, we find that stochastic heating can account for the observed ion energization; however, because the dominant contributions arise from infrequent, large-amplitude events, turbulent intermittency must be explicitly incorporated. These observations directly connect stochastic heating via breaking of the proton magnetic moment with the intermittent and inhomogeneous heating of turbulence reported in many previous studies. Our identification of stochastic heating as a dynamic mechanism responsible for intermittent heating of the solar wind has significant implications for turbulent dissipation in the lower corona, other astrophysical environments, and laboratory plasma. Show Chinese abstract

无碰撞湍流耗散在天体物理、空间物理和实验室环境中对等离子体加热非常重要，控制着能量、动量和粒子传输。 我们分析帕克太阳探测器的观测数据以理解亚阿尔芬太阳风的无碰撞加热，这与太阳日冕有关。 我们的结果表明，通过平行传播回旋波的线性共振加热无法解释亚阿尔芬区域中的湍流耗散，观测结果表明这可能在距离太阳更远的地方耗散湍流。 相反，我们发现随机加热可以解释观察到的离子能量增加；然而，由于主要贡献来自罕见的大振幅事件，必须明确纳入湍流间歇性。 这些观测结果直接将质子磁矩的破坏导致的随机加热与许多先前研究中报告的间歇性和不均匀湍流加热联系起来。 我们将随机加热识别为负责太阳风间歇性加热的动态机制，这对低日冕中的湍流耗散、其他天体物理环境和实验室等离子体具有重要意义。

[5] arXiv:2509.21098 (replaced) [cn-pdf, pdf, html, other]

Title: First Electron Acceleration in a Tunable-Velocity Laser Wakefield Show Chinese title

Title: 首次电子加速在可调速度激光等离子体波浪场中

Aaron Liberman, Anton Golovanov, Slava Smartsev, Anda-Maria Talposi, Sheroy Tata, Victor Malka

Comments: 9 pages, 3 figures

Subjects: Accelerator Physics (physics.acc-ph) ; Optics (physics.optics) ; Plasma Physics (physics.plasm-ph)

We present the first experimental confirmation that a laser-wakefield accelerator produced by a flying focus pulse is able to maintain the coherent structures necessary to accelerate electrons to relativistic energies. Through a combination of spatio-temporal near-field shaping of the beam and focusing with an axiparabola - a long-focal-depth mirror that produces a quasi-Bessel beam - the propagation velocity of the wakefield is tuned to control the maximum electron energy achievable. The experimental data are supported by advanced optical and particle-in-cell simulations and are aligned with a simplified analytical model. Together, the results significantly strengthen the case for the flying-focus wakefield as a strategy for mitigating dephasing in laser-wakefield acceleration. Show Chinese abstract

我们首次实验确认，由飞行焦点脉冲产生的激光等离子体加速器能够保持必要的相干结构，以将电子加速到相对论能量。 通过结合光束的时空近场整形以及使用轴抛物面镜——一种产生准贝塞尔光束的长焦深镜片——来调节等离子体波的传播速度，从而控制可实现的最大电子能量。 实验数据得到了先进的光学和粒子模拟的支持，并与简化的分析模型一致。 综上所述，这些结果显著加强了飞行焦点等离子体波作为减轻激光等离子体加速中去相位效应策略的依据。