标题： 三维粒子-网格模拟横向不均匀等离子体中圆偏振惯性阿尔芬波对粒子的加速 显示英文标题

标题： Three dimensional particle-in-cell simulation of particle acceleration by circularly polarised inertial Alfven waves in a transversely inhomogeneous plasma

摘要： 通过左旋圆偏振惯性阿尔芬波（IAW）在横向不均匀等离子体中进行粒子加速的过程，是使用三维粒子-网格模拟进行研究的。 考虑一个圆柱形管，其横向于背景磁场的不均匀尺度约为离子惯性长度，在此上激发频率为$0.3 \omega_{ci}$的IAW，允许其发展三个波长。 结果是在密度梯度区域产生了随时间变化的平行电场，这些电场沿磁场方向加速电子。 IAW的驱动垂直电场也在横向方向加热离子。 这种数值设置对于太阳耀斑环和地球极光区是相关的。 这项首次的、三维的、全动力学模拟展示了在密度不均匀区域，沿磁场方向的电子加速效率约为45%，而在垂直于磁场方向的离子加热效率为75%。 后者比之前的2.5D类似研究高两倍，并与太阳耀斑粒子加速观测结果一致。 我们发现生成的平行电场局限于密度不均匀区域，并以与初始激发的IAW相同的方向和角频率旋转。 我们的数值模拟似乎也表明，太阳耀斑电子谱中常找到的“膝部”可以替代地解释为由于波粒相互作用导致的IAW的兰道阻尼（切连科夫共振效应）。 显示英文摘要

摘要： The process of particle acceleration by left-hand, circularly polarised inertial Alfven waves (IAW) in a transversely inhomogeneous plasma is studied using 3D particle-in-cell simulation. A cylindrical tube with, transverse to the background magnetic field, inhomogeneity scale of the order of ion inertial length is considered on which IAWs with frequency $0.3 \omega_{ci}$ are launched that are allowed to develop three wavelength. As a result time-varying parallel electric fields are generated in the density gradient regions which accelerate electrons in the parallel to magnetic field direction. Driven perpendicular electric field of IAWs also heats ions in the transverse direction. Such numerical setup is relevant for solar flaring loops and earth auroral zone. This first, 3D, fully-kinetic simulation demonstrates electron acceleration efficiency in the density inhomogeneity regions, along the magnetic field, of the order of 45% and ion heating, in the transverse to the magnetic field direction, of 75%. The latter is a factor of two times higher than the previous 2.5D analogous study and is in accordance with solar flare particle acceleration observations. We find that the generated parallel electric field is localised in the density inhomogeneity region and rotates in the same direction and with the same angular frequency as the initially launched IAW. Our numerical simulations seem also to suggest that the "knee" often found in the solar flare electron spectra can alternatively be interpreted as the Landau damping (Cerenkov resonance effect) of IAWs due to the wave-particle interactions.