Energy dissipation and entropy in collisionless plasma
Energy dissipation and entropy in collisionless plasma
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DOI：
10.1103/physreve.101.033208
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发表时间：
2020-03-24
影响因子：
2.4
通讯作者：
Guo, Fan
中科院分区：
文献类型：
--
作者：
Du, Senbei;Zank, Gary P.;Guo, Fan
众所周知，从粒子碰撞的角度来看，无碰撞系统是无耗散的，因此熵守恒。然而，磁重联和湍流等过程似乎可以将大规模的磁能转化为热能。本文研究了无碰撞等离子体的加热和扩散。耗散过程中讨论的各向同性和gyrotropic形式的流体熵。演化方程的熵推导出，它们揭示了机制，导致流体熵的变化。这些方程是通过多重联电流片的无碰撞粒子模拟验证的。除了以前的研究结果有关的压力张量，我们强调热通量的耗散过程中的作用。
It is well known that collisionless systems are dissipation free from the perspective of particle collision and thus conserve entropy. However, processes such as magnetic reconnection and turbulence appear to convert large-scale magnetic energy into heat. In this paper, we investigate the energization and heating of collisionless plasma. The dissipation process is discussed in terms of fluid entropy in both isotropic and gyrotropic forms. Evolution equations for the entropy are derived and they reveal mechanisms that lead to changes in fluid entropy. These equations are verified by a collisionless particle-in-cell simulation of multiple reconnecting current sheets. In addition to previous findings regarding the pressure tensor, we emphasize the role of heat flux in the dissipation process.