脉冲功率驱动的辐射冷却磁重联模拟
Simulations of Radiatively Cooled Magnetic Reconnection Driven by Pulsed Power
AI总结：
本文通过2D和3D模拟建模MARZ实验，研究辐射冷却对磁重联的影响，发现辐射损失超过加热时重联层发生辐射坍缩，加速重联率并抑制等离子体团不稳定性。
摘要：
磁重联是天体物理环境中的重要过程，它重新配置磁场拓扑并将磁能转化为热能和动能。在黑洞日冕和脉冲星磁层等极端天体物理系统中，辐射冷却通过耗散内能来改变能量分配，这可能导致重联层的辐射坍缩。本文进行了2D和3D模拟以建模MARZ（Z机器上的磁重联）实验，旨在获得实验室中研究此前未探索的辐射冷却区域所需的冷却率。这些模拟在GORGON（一种欧拉电阻性磁流体力学代码）中进行，建模了包含Z机器（桑迪亚国家实验室）上由20 MA电流驱动的两个爆炸线阵列的实验几何结构。辐射损失使用原子代码Spk计算的非局部热力学平衡表实现，通过实施局部辐射损失模型和P$_{1/3}$多群辐射输运探讨辐射输运效应。负载产生高碰撞、超阿尔芬（$M_{A} \approx 1.5$）、超音速（$M_S \approx 4-5$）等离子体流，形成重联层（$L/δ \approx 100, S_L \approx 400$）。当辐射损失超过欧姆和压缩加热（$τ_{cool}^{-1}/τ_A^{-1} \approx 100$）时，重联层发生辐射坍缩；这产生冷的高度压缩电流片，导致重联率加速，与理论预测一致。最后，电流片对等离子体团不稳定性不稳定，但磁岛在射出层之前被强辐射冷却熄灭。
英文摘要：
Magnetic reconnection is an important process in astrophysical environments, as it re-configures magnetic field topology and converts magnetic energy into thermal and kinetic energy. In extreme astrophysical systems, such as black hole coronae and pulsar magnetospheres, radiative cooling modifies the energy partition by radiating away internal energy, which can lead to the radiative collapse of the layer. In this paper, we perform 2D & 3D simulations to model the MARZ (Magnetic Reconnection on Z) experiments, which are designed to access cooling rates in the laboratory necessary to investigate reconnection in a previously unexplored radiatively-cooled regime. These simulations are performed in GORGON, an Eulerian resistive magnetohydrodynamic code, which models the experimental geometry comprising two exploding wire arrays driven by 20 MA of current on the Z machine (Sandia National Laboratories). Radiative losses are implemented using non-local thermodynamic equilibrium tables computed using the atomic code Spk, and we probe the effects of radiation transport by implementing both a local radiation loss model and P$_{1/3}$ multi-group radiation transport. The load produces highly collisional, super-Alfvénic $(M_{A} \approx 1.5)$, supersonic $(M_S \approx 4-5)$ plasma flows which generate a reconnection layer ($L/δ \approx 100, S_L \approx 400$). The reconnection layer undergoes radiative collapse when the radiative losses exceed Ohmic and compressional heating $τ_{cool}^{-1}/τ_A^{-1} \approx 100$; this generates a cold strongly compressed current sheet, leading to an accelerated reconnection rate, consistent with theoretical predictions. Finally, the current sheet is unstable to the plasmoid instability, but the magnetic islands are extinguished by strong radiative cooling before ejection from the layer.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
