2016
DOI: 10.1007/s11207-016-0942-x
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The Origin of Element Abundance Variations in Solar Energetic Particles

Abstract: Abundance enhancements, during acceleration and transport in both gradual and impulsive solar energetic particle (SEP) events, vary approximately as power laws in the mass-to-charge ratio [A/Q] of the ions. Since the Q-values depend upon the electron temperature of the source plasma, this has allowed a determination of this temperature from the pattern of element-abundance enhancements and a verification of the expected inverse-time dependence of the power of A/Q for diffusive transport of ions from the SEP ev… Show more

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Cited by 18 publications
(40 citation statements)
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References 145 publications
(281 reference statements)
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“…Nitta et al, 2006). Reames (2016b). Both populations involve T ≈ 3MK impulsive SEP ions from magnetic reconnection sites in solar jets which may be reaccelerated by a shock wave; proton excesses are produced when those shocks also include protons from the ambient coronal material.…”
Section: Comparing Cmesmentioning
confidence: 99%
See 1 more Smart Citation
“…Nitta et al, 2006). Reames (2016b). Both populations involve T ≈ 3MK impulsive SEP ions from magnetic reconnection sites in solar jets which may be reaccelerated by a shock wave; proton excesses are produced when those shocks also include protons from the ambient coronal material.…”
Section: Comparing Cmesmentioning
confidence: 99%
“…Suggested explanations for the broad distribution of source abundances in impulsive events (below) from variations in single localized jet events where ejecta may or may not drive a shock, and the narrow distribution in high-T gradual events (above) where pre-accelerated impulsive seed populations from many individual jets are averaged by a large shock. Abundance distributions shown (fromReames, 2016b) are equivalent to those that were shown in the lower panels if Figures 3, and 6.…”
mentioning
confidence: 92%
“…About 25% of gradual events have been found to have ≈3 MK source temperatures, relatively weak shocks, and abundances with enhancements that look like reaccelerated impulsive SEP events. These events are believed to involve preferential shock acceleration of residual impulsive suprathermal ions [28,[77][78][79]. Reacceleration of residual impulsive suprathermal ions might be especially favored when the magnetic field lies near the plane of the accelerating shock, so only fast particles can overtake the shock from downstream [77,78].…”
Section: Note In Panel (D) Ofmentioning
confidence: 99%
“…These gradual SEP events involving reaccelerated ≈3 MK ions have much smaller variations of source abundance than do single impulsive SEP events of the same temperature, especially in abundance ratios, like He/C, where both ions should be fully ionized at this temperature. Figure 7 shows a suggested explanation for this [75,79].…”
Section: Note In Panel (D) Ofmentioning
confidence: 99%
“…These shock waves accelerate SEPs (Lee, 1983(Lee, , 2005Zank, Rice, and Wu, 2000;Cliver, Kahler, and Reames, 2004;Ng and Reames, 2008;Gopalswamy et al 2012;Lee, Mewaldt, and Giacalone, 2012;Desai and Giacalone, 2016;Reames, 2017a), requiring shock speeds above 500 -700 km s -1 (Reames, Kahler, and Ng, 1997), and accelerating ions over an extremely broad region of the heliosphere (Reames, Barbier, and Ng, 1996;Rouillard et al, 2012;Cohen, Mason, Mewaldt, 2017;Reames, 2017b). Generally, the shock waves sample the 1 -2 MK coronal plasma (Reames, 2016a(Reames, , 2016b(Reames, , 2018b. Power-law dependence in gradual events can come from rigidity-dependent scattering of ions during transport (Parker, 1963;Ng, Reames, and Tylka, 1999Reames, 2016aReames, , 2016b, which results in dependence upon A/Q when ion abundances are compared at the same particle velocity.…”
Section: Introductionmentioning
confidence: 99%