Datta R, Chandler K, Myers C E, Chittenden J P, Crilly A J, Aragon C, Ampleford D J, Banasek J T, Edens A, Fox W R, Hansen S B, Harding E C, Jennings C A, Ji H, Kuranz C C, Lebedev S V, Looker Q, Patel S G, Porwitzky A, Shipley G A, Uzdensky D A, Yager-Elorriaga D A, Hare J D
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Massachusetts 02139, Cambridge, USA.
Sandia National Laboratories, Albuquerque, New Mexico 87123-1106, USA.
Phys Rev Lett. 2024 Apr 12;132(15):155102. doi: 10.1103/PhysRevLett.132.155102.
We present the first experimental study of plasmoid formation in a magnetic reconnection layer undergoing rapid radiative cooling, a regime relevant to extreme astrophysical plasmas. Two exploding aluminum wire arrays, driven by the Z machine, generate a reconnection layer (S_{L}≈120) in which the cooling rate far exceeds the hydrodynamic transit rate (τ_{hydro}/τ_{cool}>100). The reconnection layer generates a transient burst of >1 keV x-ray emission, consistent with the formation and subsequent rapid cooling of the layer. Time-gated x-ray images show fast-moving (up to 50 km s^{-1}) hotspots in the layer, consistent with the presence of plasmoids in 3D resistive magnetohydrodynamic simulations. X-ray spectroscopy shows that these hotspots generate the majority of Al K-shell emission (around 1.6 keV) prior to the onset of cooling, and exhibit temperatures (170 eV) much greater than that of the plasma inflows and the rest of the reconnection layer, thus providing insight into the generation of high-energy radiation in radiatively cooled reconnection events.
我们展示了在经历快速辐射冷却的磁重联层中形成等离子体团的首个实验研究，该状态与极端天体物理等离子体相关。由Z机器驱动的两个爆炸铝丝阵列产生了一个重联层（(S_{L}≈120)），其中冷却速率远超过流体动力学传输速率（(\tau_{hydro}/\tau_{cool}>100)）。重联层产生了一个超过1keV的X射线发射的瞬态爆发，这与该层的形成及随后的快速冷却一致。时间选通X射线图像显示该层中有快速移动（速度高达50km s⁻¹）的热点，这与三维电阻磁流体动力学模拟中存在等离子体团一致。X射线光谱表明，这些热点在冷却开始之前产生了大部分的铝K壳层发射（约1.6keV），并且其温度（170eV）远高于等离子体流入和重联层其余部分的温度，从而为辐射冷却重联事件中高能辐射的产生提供了见解。
