arXiv: Plasma Physics最新文献_第9页

Necessary and sufficient conditions for quasisymmetry 准对称的充分必要条件

arXiv: Plasma Physics Pub Date : 2020-04-23 DOI: 10.1063/5.0008551

E. Rodríguez, P. Helander, Ashis Bhattacharjee

引用次数: 31

Trajectory of a flying plasma mirror traversing a target with density gradient 等离子体反射镜在密度梯度目标上的飞行轨迹

arXiv: Plasma Physics Pub Date : 2020-04-22 DOI: 10.1063/5.0012374

Pisin Chen, G. Mourou

引用次数: 16

Linear dispersion theory of parallel electromagnetic modes for regularized Kappa-distributions 正则化kappa分布的平行电磁模线性色散理论

arXiv: Plasma Physics Pub Date : 2020-04-17 DOI: 10.1063/1.5145181

E. Husidic, M. Lazar, H. Fichtner, K. Scherer, P. Astfalk

{"title":"Linear dispersion theory of parallel electromagnetic modes for regularized Kappa-distributions","authors":"E. Husidic, M. Lazar, H. Fichtner, K. Scherer, P. Astfalk","doi":"10.1063/1.5145181","DOIUrl":"https://doi.org/10.1063/1.5145181","url":null,"abstract":"The velocity particle distributions measured in-situ in space plasmas deviate from Maxwellian (thermal) equilibrium, showing enhanced suprathermal tails which are well described by the standard Kappa-distribution (SKD). Despite its successful application, the SKD is frequently disputed due to a series of unphysical implications like diverging velocity moments, preventing a macroscopic description of the plasma. The regularized Kappa-distribution (RKD) has been introduced to overcome these limitations, but the dispersion properties of RKD-plasmas are not explored yet. In the present paper we compute the wavenumber dispersion of the frequency and damping or growth rates for the electromagnetic modes in plasmas characterized by the RKD. This task is accomplished by using the grid-based kinetic dispersion solver LEOPARD developed for arbitrary gyrotropic distributions [P. Astfalk and F. Jenko, J. Geophys. Res. 122, 89 (2017)]. By reproducing previous results obtained for the SKD and Maxwellian, we validate the functionality of the code. Furthermore, we apply the isotropic as well as the anisotropic RKDs to investigate stable electromagnetic electron-cyclotron (EMEC) and ion-cyclotron (EMIC) modes as well as temperature-anisotropy-driven instabilities, both for the case $T_perp / T_parallel > 1$ (EMEC and EMIC instabilities) and for the case $T_perp / T_parallel < 1$ (proton and electron firehose instabilities), where $parallel$ and $perp$ denote directions parallel and perpendicular to the local time-averaged magnetic field. Provided that the cutoff parameter $alpha$ is small enough, the results show that the RKDs reproduce the dispersion curves of the SKD plasmas at both qualitative and quantitative levels. For higher values, however, physically significant deviation occurs.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76938532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 13

Self-acceleration and energy channeling in the saturation of the ion-sound instability in a bounded plasma 有界等离子体中离子声不稳定性饱和时的自加速和能量通道

arXiv: Plasma Physics Pub Date : 2020-04-16 DOI: 10.1063/5.0016440

Liang Xu, A. Smolyakov, S. Janhunen, I. Kaganovich

引用次数: 1

Compton recoil effects in staging of laser wakefield accelerators 激光尾流场加速器的康普顿后坐力效应

arXiv: Plasma Physics Pub Date : 2020-04-15 DOI: 10.1103/PHYSREVACCELBEAMS.23.071602

M. Streeter, Z. Najmudin

引用次数: 0

Ion versus Electron Heating in Compressively Driven Astrophysical Gyrokinetic Turbulence 压缩驱动的天体物理回旋动力学湍流中的离子与电子加热

arXiv: Plasma Physics Pub Date : 2020-04-10 DOI: 10.1103/physrevx.10.041050

Y. Kawazura, A. Schekochihin, M. Barnes, J. TenBarge, Y. Tong, K. Klein, W. Dorland

{"title":"Ion versus Electron Heating in Compressively Driven Astrophysical Gyrokinetic Turbulence","authors":"Y. Kawazura, A. Schekochihin, M. Barnes, J. TenBarge, Y. Tong, K. Klein, W. Dorland","doi":"10.1103/physrevx.10.041050","DOIUrl":"https://doi.org/10.1103/physrevx.10.041050","url":null,"abstract":"The partition of irreversible heating between ions and electrons in compressively driven (but subsonic) collisionless turbulence is investigated by means of nonlinear gyrokinetic simulations. We derive a prescription for the ion-to-electron heating ratio $Q_{text{i}}/Q_{text{e}}$ as a function of the compressive-to-Alfvenic driving power ratio $P_{text{compr}}/P_{text{AW}}$, of the ratio of ion thermal pressure to magnetic pressure $beta_{text{i}}$, and of the ratio of ion-to-electron background temperatures $T_{text{i}}/T_{text{e}}$. It is shown that $Q_{text{i}}/Q_{text{e}}$ is an increasing function of $P_{text{compr}}/P_{text{AW}}$. When the compressive driving is sufficiently large, $Q_{text{i}}/Q_{text{e}}$ approaches $simeq P_{text{compr}}/P_{text{AW}}$. This indicates that, in turbulence with large compressive fluctuations, the partition of heating is decided at the injection scales, rather than at kinetic scales. Analysis of phase-space spectra shows that the energy transfer from inertial-range compressive fluctuations to sub-Larmor-scale kinetic Alfven waves is absent for both low and high $beta_{text{i}}$, meaning that the compressive driving is directly connected to the ion entropy fluctuations, which are converted into ion thermal energy. This result suggests that preferential electron heating is a very special case requiring low $beta_{text{i}}$ and no, or weak, compressive driving. Our heating prescription has wide-ranging applications, including to the solar wind and to hot accretion disks such as M87 and Sgr A*.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79127702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 13

Two-time energy spectrum of weak magnetohydrodynamic turbulence 弱磁流体动力学湍流的二次能谱

arXiv: Plasma Physics Pub Date : 2020-04-07 DOI: 10.1103/physrevresearch.2.023189

J. C. Perez, Augustus A. Azelis, S. Bourouaine

{"title":"Two-time energy spectrum of weak magnetohydrodynamic turbulence","authors":"J. C. Perez, Augustus A. Azelis, S. Bourouaine","doi":"10.1103/physrevresearch.2.023189","DOIUrl":"https://doi.org/10.1103/physrevresearch.2.023189","url":null,"abstract":"In this work a weak-turbulence closure is used to determine the structure of the two-time power spectrum of weak magnetohydrodynamic (MHD) turbulence from the nonlinear equations describing the dynamics. The two-time energy spectrum is a fundamental quantity in turbulence theory from which most statistical properties of a homogeneous turbulent system can be derived. A closely related quantity, obtained via a spatial Fourier transform, is the two-point two-time correlation function describing the space-time correlations arising from the underlying dynamics of the turbulent fluctuations. Both quantities are central in fundamental turbulence theories as well as in the analysis of turbulence experiments and simulations. However, a first-principles derivation of these quantities has remained elusive due to the statistical closure problem, in which dynamical equations for correlations at order $n$ depend on correlations of order $n+1$. The recent launch of the Parker Solar Probe (PSP), which will explore the near-Sun region where the solar wind is born, has renewed the interest in the scientific community to understand the structure, and possible universal properties of space-time correlations. The weak MHD turbulence regime that we consider in this work allows for a natural asymptotic closure of the two-time spectrum, which may be applicable to other weak turbulence regimes found in fluids and plasmas. An integro-differential equation for the scale-dependent temporal correlation function is derived for incompressible Alfvenic fluctuations whose nonlinear dynamics is described by the reduced MHD equations.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83729280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Interaction of Ultraintense Radially-Polarized Laser Pulses with Plasma Mirrors 超强辐射偏振激光脉冲与等离子体反射镜的相互作用

arXiv: Plasma Physics Pub Date : 2020-04-07 DOI: 10.1103/physrevx.10.041064

N. Zaïm, D. Gu'enot, L. Chopineau, A. Denoeud, O. Lundh, H. Vincenti, F. Qu'er'e, J. Faure

{"title":"Interaction of Ultraintense Radially-Polarized Laser Pulses with Plasma Mirrors","authors":"N. Zaïm, D. Gu'enot, L. Chopineau, A. Denoeud, O. Lundh, H. Vincenti, F. Qu'er'e, J. Faure","doi":"10.1103/physrevx.10.041064","DOIUrl":"https://doi.org/10.1103/physrevx.10.041064","url":null,"abstract":"We present experimental results of vacuum laser acceleration (VLA) of electrons using radially polarized laser pulses interacting with a plasma mirror. Tightly focused radially polarized laser pulses have been proposed for electron acceleration because of their strong longitudinal electric field, making them ideal for VLA. However, experimental results have been limited until now because injecting electrons into the laser field has remained a considerable challenge. Here, we demonstrate experimentally that using a plasma mirror as an injector solves this problem and permits to inject electrons at the ideal phase of the laser, resulting in the acceleration of electrons along the laser propagation direction while reducing the electron beam divergence compared to the linear polarization case. We obtain electron bunches with few-MeV energies and a 200 pC charge, thus demonstrating for the first time electron acceleration to relativistic energies using a radially polarized laser. High-harmonic generation from the plasma surface is also measured and provides additional insight into the injection of electrons into the laser field upon its reflection on the plasma mirror. Detailed comparisons between experimental results and full 3D simulations unravel the complex physics of electron injection and acceleration in this new regime: we find that electrons are injected into the radially polarized pulse in the form of two spatially-separated bunches emitted from the p-polarized regions of the focus. Finally, we leverage on the insight brought by this study to propose and validate a more optimal experimental configuration that can lead to extremely peaked electron angular distributions and higher energy beams.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85861575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

Spin Filter for Polarized Electron Acceleration in Plasma Wakefields 等离子体尾流场中极化电子加速的自旋滤波器

arXiv: Plasma Physics Pub Date : 2020-04-06 DOI: 10.1103/physrevapplied.13.044064

Yitong Wu, L. Ji, X. Geng, Johannes Thomas, M. Büscher, A. Pukhov, A. Hützen, Lingang Zhang, B. Shen, Ruxin Li

{"title":"Spin Filter for Polarized Electron Acceleration in Plasma Wakefields","authors":"Yitong Wu, L. Ji, X. Geng, Johannes Thomas, M. Büscher, A. Pukhov, A. Hützen, Lingang Zhang, B. Shen, Ruxin Li","doi":"10.1103/physrevapplied.13.044064","DOIUrl":"https://doi.org/10.1103/physrevapplied.13.044064","url":null,"abstract":"We propose a filter method to generate electron beams of high polarization from bubble and blow-out wakefield accelerators. The mechanism is based on the idea to identify all electron-beam subsets with low-polarization and to filter them out by an X-shaped slit placed right behind the plasma accelerator. To find these subsets we investigate the dependence between the initial azimuthal angle and the spin of single electrons during the trapping process. This dependence shows that transverse electron spins preserve their orientation during injection if they are initially aligned parallel or anti-parallel to the local magnetic field. We derive a precise correlation of the local beam polarization as a function of the coordinate and the electron phase angle. Three-dimensional particle-in-cell simulations, incorporating classical spin dynamics, show that the beam polarization can be increased from 35% to about 80% after spin filtering. The injected flux is strongly restricted to preserve the beam polarization, e.g. <1kA in Ref.[27]. This limitation is removed by employing the proposed filter mechanism. The robust of the method is discussed that contains drive beam fluctuations, jitters, the thickness of the filter and initial temperature. This idea marks an efficient and simple strategy to generate energetic polarized electron beams based on wakefield acceleration","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79097265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 10

Noise-induced magnetic field saturation in kinetic simulations 动力学模拟中的噪声感应磁场饱和

arXiv: Plasma Physics Pub Date : 2020-04-01 DOI: 10.1017/S0022377820000707

J. Juno, M. Swisdak, J. TenBarge, V. Skoutnev, A. Hakim

引用次数: 9