Nonthermal electron and ion acceleration by magnetic reconnection in large laser-driven plasmas
Nonthermal electron and ion acceleration by magnetic reconnection in large laser-driven plasmas
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DOI：
10.1063/5.0021169
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发表时间：
2020-11
影响因子：
2.2
通讯作者：
S. Totorica;M. Hoshino;Tom Abel;F. Fiuza
中科院分区：
文献类型：
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作者：
S. Totorica;M. Hoshino;Tom Abel;F. Fiuza
磁重联是一个基本的等离子体过程，被认为在空间物理和天体物理中与爆炸现象相关的非热粒子的产生中起着关键作用。在高能量密度设施的实验开始探测在高伦德奎斯特数和大系统尺寸的重联的微观物理。我们已经进行了粒子在细胞（PIC）模拟，探索粒子加速激光驱动的重联实验相关的参数。我们研究粒子加速在大系统的尺寸，可能很快产生的最有活力的激光驱动器，如在国家点火装置。在这些条件下，我们显示了达到多等离子体制度，其中等离子体加速成为主导的可能性。我们的研究结果表明，从X点到等离子体团占主导地位的加速与合并和收缩的等离子体团，进一步扩展的粒子分布的幂律尾部的最大能量的过渡电子。我们还发现第一次出现的系统大小相关的非热离子加速驱动重联，在足够大的尺寸的离子的磁化允许它们被包含在磁场和通电的直接X点加速。在可行的实验条件下，电子和离子的能量可达到1000 ~ 1000，e / k B Te> 100，i / k B Ti> 1000。利用PIC模拟与二进制Monte Carlo库仑碰撞，我们研究了碰撞等离子体团的形成和粒子加速的影响。这些结果的影响，了解重联在加速粒子在空间物理学和天体物理学中的作用进行了讨论。
Magnetic reconnection is a fundamental plasma process that is thought to play a key role in the production of nonthermal particles associated with explosive phenomena in space physics and astrophysics. Experiments at high-energy-density facilities are starting to probe the microphysics of reconnection at high Lundquist numbers and large system sizes. We have performed particle-in-cell (PIC) simulations to explore particle acceleration for parameters relevant to laser-driven reconnection experiments. We study particle acceleration in large system sizes that may be produced soon with the most energetic laser drivers available, such as at the National Ignition Facility. In these conditions, we show the possibility of reaching the multi-plasmoid regime, where plasmoid acceleration becomes dominant. Our results show the transition from X point to plasmoid-dominated acceleration associated with the merging and contraction of plasmoids that further extend the maximum energy of the power-law tail of the particle distribution for electrons. We also find for the first time a system-size-dependent emergence of nonthermal ion acceleration in driven reconnection, where the magnetization of ions at sufficiently large sizes allows them to be contained by the magnetic field and energized by direct X point acceleration. For feasible experimental conditions, electrons and ions can attain energies of ϵ max , e / k B T e > 100 and ϵ max , i / k B T i > 1000. Using PIC simulations with binary Monte Carlo Coulomb collisions, we study the impact of collisionality on plasmoid formation and particle acceleration. The implications of these results for understanding the role reconnection plays in accelerating particles in space physics and astrophysics are discussed.