Baker Daniel N
Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, 3665 Discovery Drive, 600 UCB, Boulder, CO 80303 USA.
Earth Planets Space. 2021;73(1):189. doi: 10.1186/s40623-021-01508-y. Epub 2021 Oct 19.
Discovering such structures as the third radiation belt (or "storage ring") has been a major observational achievement of the NASA Radiation Belt Storm Probes program (renamed the "Van Allen Probes" mission in November 2012). A goal of that program was to understand more thoroughly how high-energy electrons are accelerated deep inside the radiation belts-and ultimately lost-due to various wave-particle interactions. Van Allen Probes studies have demonstrated that electrons ranging up to 10 megaelectron volts (MeV) or more can be produced over broad regions of the outer Van Allen zone on timescales as short as a few minutes. The key to such rapid acceleration is the interaction of "seed" populations of ~ 10-200 keV electrons (and subsequently higher energies) with electromagnetic waves in the lower band (whistler-mode) chorus frequency range. Van Allen Probes data show that "source" electrons (in a typical energy range of one to a few tens of keV energy) produced by magnetospheric substorms play a crucial role in feeding free energy into the chorus waves in the outer zone. These chorus waves then, in turn, rapidly heat and accelerate the tens to hundreds of keV seed electrons injected by substorms to much higher energies. Hence, we often see that geomagnetic activity driven by strong solar storms (coronal mass ejections, or CMEs) commonly leads to ultra-relativistic electron production through the intermediary step of waves produced during intense magnetospheric substorms. More generally, wave-particle interactions are of fundamental importance over a broad range of energies and in virtually all regions of the magnetosphere. We provide a summary of many of the wave modes and particle interactions that have been studied in recent times.
发现诸如第三辐射带（或“存储环”）这样的结构是美国国家航空航天局辐射带风暴探测器计划（2012年11月更名为“范艾伦探测器”任务）的一项重大观测成果。该计划的一个目标是更全面地了解高能电子如何在辐射带深处因各种波粒相互作用而被加速——并最终损失。范艾伦探测器的研究表明，能量高达10兆电子伏特（MeV）或更高的电子可以在范艾伦外区的广阔区域内，在短短几分钟的时间尺度上产生。这种快速加速的关键在于能量约为10 - 200千电子伏特的“种子”电子群体（以及随后更高的能量）与低频带（啸声模式）合声频率范围内的电磁波相互作用。范艾伦探测器的数据显示，磁层亚暴产生的“源”电子（典型能量范围为一到几十千电子伏特）在将自由能量输入外区的合声波中起着关键作用。然后，这些合声波反过来迅速加热并将亚暴注入的几十到几百千电子伏特的种子电子加速到更高的能量。因此，我们经常看到，由强烈太阳风暴（日冕物质抛射，即CME）驱动的地磁活动通常会通过强烈磁层亚暴期间产生的波的中间步骤导致超相对论电子的产生。更一般地说，波粒相互作用在广泛的能量范围内以及几乎磁层的所有区域都具有根本重要性。我们总结了近期研究的许多波模式和粒子相互作用。
