The relative abundances of chemical elements and isotopes have been our most effective tool in identifying and understanding the physical processes that control populations of energetic particles. The early surprise in solar energetic particles (SEPs) was 1000-fold enhancements in He3/4He${}^{3}\mbox{He}/{}^{4}\mbox{He}$ from resonant wave-particle interactions in the small “impulsive” SEP events that emit electron beams that produce type III radio bursts. Further studies found enhancements in Fe/O, then extreme enhancements in element abundances that increase with mass-to-charge ratio A/Q$A/Q$, rising by a factor of 1000 from He to Au or Pb arising in magnetic reconnection regions on open field lines in solar jets. In contrast, in the largest SEP events, the “gradual” events, acceleration occurs at shock waves driven out from the Sun by fast, wide coronal mass ejections (CMEs). Averaging many events provides a measure of solar coronal abundances, but A/Q$A/Q$-dependent scattering during transport causes variations with time; thus if Fe scatters less than O, Fe/O is enhanced early and depleted later. To complicate matters, shock waves often reaccelerate impulsive suprathermal ions left over or trapped above active regions that have spawned many impulsive events. Direct measurements of ionization states Q$Q$ show coronal temperatures of 1–2 MK for most gradual events, but impulsive events often show stripping by matter traversal after acceleration. Direct measurements of Q$Q$ are difficult and often unavailable. Since both impulsive and gradual SEP events have abundance enhancements that vary as powers of A/Q$A/Q$, we can use abundances to deduce the probable Q$Q$-values and the source plasma temperatures during acceleration, ≈3 MK for impulsive SEPs. This new technique also allows multiple spacecraft to measure temperature variations across the face of a shock wave, measurements otherwise unavailable and provides a new understanding of abundance variations in the element He. Comparing coronal abundances from SEPs and from the slow solar wind as a function of the first ionization potential (FIP) of the elements, remaining differences are for the elements C, P, and S. The theory of the fractionation of ions by Alfvén waves shows that C, P, and S are suppressed because of wave resonances during chromospheric transport on closed magnetic loops but not on open magnetic fields that supply the solar wind. Shock waves can accelerate ions from closed coronal loops that easily escape as SEPs, while the solar wind must emerge on open fields.

中文翻译：

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太阳能粒子中的丰度、电离态、温度和 FIP

化学元素和同位素的相对丰度一直是我们识别和理解控制高能粒子群的物理过程的最有效工具。太阳高能粒子 (SEP) 的早期惊喜是来自共振波粒相互作用的 He3/4He${}^{3}\mbox{He}/{}^{4}\mbox{He}$ 增强了 1000 倍在发射电子束的小型“脉冲”SEP 事件中，产生 III 型射电爆发。进一步的研究发现 Fe/O 的增强，然后元素丰度的极端增强随着质荷比 A/Q$A/Q$ 的增加而增加，从 He 到 Au 或 Pb 增加了 1000 倍，出现在磁重联区在太阳射流的开放场线上。相比之下，在最大的 SEP 事件中，“渐进”事件，加速发生在从太阳快速驱出的冲击波，宽日冕物质抛射（CME）。平均许多事件提供了日冕丰度的度量，但传输过程中依赖于 A/Q$A/Q$ 的散射会导致随时间的变化；因此，如果 Fe 的散射小于 O，则 Fe/O 会提前增强并稍后耗尽。使问题复杂化的是，冲击波通常会重新加速遗留或困在活动区域​​上方的脉冲超热离子，这些区域已经产生了许多脉冲事件。对于大多数渐进事件，直接测量电离状态 Q$Q$ 显示日冕温度为 1-2 MK，但脉冲事件通常显示加速后物质穿越的剥离。Q$Q$ 的直接测量是困难的并且经常无法获得。由于冲动性和渐进性 SEP 事件都具有随 A/Q$A/Q$ 的幂而变化的丰度增强，我们可以使用丰度来推导出可能的 Q$Q$ 值和加速过程中的源等离子体温度，对于脉冲 SEP，≈3 MK。这项新技术还允许多个航天器测量冲击波表面的温度变化，否则无法测量，并提供了对元素 He 丰度变化的新理解。比较来自 SEP 和来自慢太阳风的日冕丰度作为元素的第一电离势 (FIP) 的函数，剩余的差异是针对元素 C、P 和 S。阿尔文波的离子分馏理论表明C、P 和 S 被抑制，因为在闭合磁环上的色球传输期间的波共振，而不是在提供太阳风的开放磁场上。