Reames D
NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA.
Radiat Meas. 1999 Jun;30(3):297-308. doi: 10.1016/s1350-4487(99)00066-9.
In the large solar energetic particle (SEP) events that constitute a serious radiation hazard, particles are accelerated at shock waves driven out from the Sun by coronal mass ejections (CMEs). A self-regulating mechanism of wave formation by the streaming particles limits SEP intensities early in the event. Hazardous intensities do not occur until the arrival of the shock itself. This provides an opportunity to warn astronauts to take shelter after the onset of the event at the Sun and before arrival of the shock, a time of approximately 12 h or more. The actual time history of particle intensities depends strongly on the longitude of the event at the Sun, on the width the CME, and especially on the speed of the shock. Fortunately, hazardous events are relatively rare. Unfortunately, this gives us few events to study, so we are forced to extrapolate knowledge gained at lower energies in the frequent smaller events. It is essential that the spacecraft with our best instrumentation be positioned outside the Earth's magnetosphere where they can observe these rare large events when they do occur.
在构成严重辐射危害的大型太阳高能粒子（SEP）事件中，粒子在日冕物质抛射（CME）从太阳驱出的激波处被加速。由流动粒子形成波的自调节机制在事件早期限制了SEP强度。直到激波本身到达才会出现危险强度。这提供了一个机会，在事件在太阳发生后且激波到达之前，大约12小时或更长时间内，警告宇航员寻找掩护。粒子强度的实际时间历程强烈依赖于事件在太阳上的经度、CME的宽度，尤其是激波的速度。幸运的是，危险事件相对较少。不幸的是，这使得我们可供研究的事件很少，所以我们不得不外推在频繁发生的较小事件中在较低能量下获得的知识。至关重要的是，配备我们最佳仪器的航天器要定位在地球磁层之外，以便在这些罕见的大型事件发生时能够进行观测。
