Replication Data for: Interaction of cold streaming protons with the reconnection process

Particle-in-cell simulation of magnetotail reconnection with streaming cold protons in inflow regions. The code solves Vlasov-Maxwell system, and outputs electric and magnetic fields, current densities, and densities. Used for manuscript titled 'Interaction of cold streaming protons with the reconnection process' by Tenfjord et al., 2020. Details, simulation setup and design described in manuscript.
We employ a 2.5D particle-in-cell simulation to study a scenario where the reconnection process captures cold streaming protons. As soon as the tailward streaming protons become involved, they contribute to the overall momentum balance, altering the initially symmetric dynamics. Adding tailward-directed momentum to the reconnection process results in a tailward propagation of the reconnection site. We investigate how the reconnection process reorganizes itself due to the changing momentum conditions on the kinetic scale, and how the reconnection rate is affected. We find that adding tailward momentum, does not result in a significantly different reconnection rate compared to the case without cold streaming protons, when scaled to the total Alfven velocity. This implies that the effect of changing inflow conditions due to the motion of the reconnection site appears to be minimal. The dynamics of the particles are however, significantly different depending on whether they enter on the tailward or Earthward side of the reconnection site. On one side they are reflected and thermalized, while on the opposite side they are picked-up and accelerated. The particle dynamics result in an asymmetry in the electric field between the two outflow regions. Also, since the initial plasma sheet population is swept up on one side and flushed out on the other, a multiscale diffusion region exists only on one side, resulting in asymmetries in the Hall electric field and in the magnetic field configuration. Our results are important for understanding the development and dynamics of magnetospheric substorms and storms.

本数据集为流入区存在冷流质子的磁尾重联粒子胞内（Particle-in-cell, PIC）模拟数据。所用代码求解弗拉索夫-麦克斯韦（Vlasov-Maxwell）方程组，输出电场、磁场、电流密度及粒子数密度。本数据集对应Tenfjord等人2020年发表的题为《冷流质子与重联过程的相互作用》的学术手稿，模拟细节、设置与设计均见于该手稿。

本研究采用2.5维粒子胞内模拟，探究重联过程捕获冷流质子的物理场景。当沿尾向（背向地球）运动的冷质子参与重联过程后，会对整体动量平衡产生贡献，改变初始对称的动力学演化。为重联过程添加背向地球的动量后，重联位点会沿尾向传播。本研究旨在探究：在动理学尺度下，动量条件的变化如何使重联过程发生自组织重构，以及重联率受到何种影响。研究发现，当以总阿尔文（Alfvén）速度进行归一化时，添加背向地球动量的模拟与无冷流质子的基准模拟，其重联率并无显著差异。这表明，由重联位点运动所引发的流入区条件变化，其影响程度相对有限。不过，粒子的动力学行为会因其进入重联位点的侧别（背向地球侧或朝向地球侧）而存在显著差异：在一侧质子会被反射并热化，而在另一侧则会被拾取并加速。粒子的动力学过程会导致两个外流区域间的电场出现不对称性。此外，由于初始等离子体片粒子群仅在一侧被扫集并从另一侧被排出，仅单侧存在多尺度扩散区，进而引发霍尔电场与磁场位形的不对称性。本研究结果对于理解磁层亚暴与磁层风暴的演化过程与动力学机制具有重要意义。