Raptis Savvas, Karlsson Tomas, Vaivads Andris, Pollock Craig, Plaschke Ferdinand, Johlander Andreas, Trollvik Henriette, Lindqvist Per-Arne
Division of Space and Plasma Physics - KTH Royal Institute of Technology, Stockholm, Sweden.
Denali Scientific, Fairbanks, AK, 99709, USA.
Nat Commun. 2022 Feb 1;13(1):598. doi: 10.1038/s41467-022-28110-4.
Shocks are one of nature's most powerful particle accelerators and have been connected to relativistic electron acceleration and cosmic rays. Upstream shock observations include wave generation, wave-particle interactions and magnetic compressive structures, while at the shock and downstream, particle acceleration, magnetic reconnection and plasma jets can be observed. Here, using Magnetospheric Multiscale (MMS) we show in-situ evidence of high-speed downstream flows (jets) generated at the Earth's bow shock as a direct consequence of shock reformation. Jets are observed downstream due to a combined effect of upstream plasma wave evolution and an ongoing reformation cycle of the bow shock. This generation process can also be applicable to planetary and astrophysical plasmas where collisionless shocks are commonly found.
激波是自然界中最强大的粒子加速器之一，并且与相对论电子加速和宇宙射线有关。上游激波观测包括波的产生、波粒相互作用和磁压缩结构，而在激波处及下游，可以观测到粒子加速、磁重联和等离子体喷流。在此，我们利用磁层多尺度任务（MMS）卫星展示了地球弓形激波处产生高速下游流（喷流）的原位证据，这是激波重构的直接结果。由于上游等离子体波演化和弓形激波持续重构周期的综合作用，在下游观测到了喷流。这种产生过程也适用于普遍存在无碰撞激波的行星和天体物理等离子体。
