Fast Magnetic Reconnection in High-Energy-Density Laser-Produced Plasmas*

Recent experiments have observed magnetic reconnection in high-energy-density, laser-produced plasma bubbles [1,2], with reconnection rates observed to be much higher than can be explained by classical theory. This is a novel regime for magnetic reconnection study, characterized by extremely high magnetic fields, high plasma beta and strong, supersonic plasma inflow. Reconnection in this regime is investigated with particle-in-cell simulations. Collisionless simulations have identified two key ingredients, simultaneously present for the first time: two-fluid reconnection mediated by collisionless effects (that is, the Hall current and electron pressure tensor), and strong flux pile-up of the inflowing magnetic field [3]. These effects combine to yield reconnection rates independent of the nominal Alfv\'{e}n speed (based on the magnetic field before interaction), and simply given by the dynamic time $L/V$, in qualitative agreement with the experiments. We present detailed simulations spanning the parameter ranges of the experiments, and further compare the results of simulations with and without binary collisions, in 2D and 3D. Finally we discuss plans for future laser-driven reconnection experiments.\\[4pt] [1] P. M. Nilson, \textit{et al}, Phys. Rev. Lett. \textbf{97}, 255001 (2006).\\[0pt] [2] C. K. Li, \textit{et al}, Phys. Rev. Lett. \textbf{99}, 055001 (2007).\\[0pt] [3] W. Fox, A. Bhattacharjee, K. Germaschewski, Phys. Rev. Lett. \textbf{106}, 215003 (2011).