Schaeffer D B, Fox W, Haberberger D, Fiksel G, Bhattacharjee A, Barnak D H, Hu S X, Germaschewski K
Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA.
Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
Phys Rev Lett. 2017 Jul 14;119(2):025001. doi: 10.1103/PhysRevLett.119.025001. Epub 2017 Jul 13.
We present the first laboratory generation of high-Mach-number magnetized collisionless shocks created through the interaction of an expanding laser-driven plasma with a magnetized ambient plasma. Time-resolved, two-dimensional imaging of plasma density and magnetic fields shows the formation and evolution of a supercritical shock propagating at magnetosonic Mach number M_{ms}≈12. Particle-in-cell simulations constrained by experimental data further detail the shock formation and separate dynamics of the multi-ion-species ambient plasma. The results show that the shocks form on time scales as fast as one gyroperiod, aided by the efficient coupling of energy, and the generation of a magnetic barrier between the piston and ambient ions. The development of this experimental platform complements present remote sensing and spacecraft observations, and opens the way for controlled laboratory investigations of high-Mach number collisionless shocks, including the mechanisms and efficiency of particle acceleration.
我们展示了通过膨胀的激光驱动等离子体与磁化的环境等离子体相互作用首次在实验室中产生的高马赫数无碰撞磁化激波。对等离子体密度和磁场的时间分辨二维成像显示了以磁声马赫数(M_{ms}≈12)传播的超临界激波的形成和演化。受实验数据约束的粒子模拟进一步详细说明了激波的形成以及多离子种类环境等离子体的分离动力学。结果表明，在能量的有效耦合以及活塞与环境离子之间产生磁障的辅助下，激波在快至一个回旋周期的时间尺度上形成。该实验平台的发展补充了现有的遥感和航天器观测，并为高马赫数无碰撞激波的可控实验室研究开辟了道路，包括粒子加速的机制和效率。
