Charge-equilibration of Fe ions accelerated 
 in a hot plasma

Kovaltsov, G. A.; Barghouty, A. F.; Kocharov, L. G.; Ostryakov, V. M.; Torsti, J.

doi:10.1051/0004-6361:20010877

Cited by 28 publications

(28 citation statements)

References 24 publications

(33 reference statements)

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“…This is because processes such as: (1) chargechanging effects resulting from ionization by thermal electrons and ions, (2) mixing of sources with different ionic charge distributions, and (3) M/Q-dependent energy spectra, do not significantly affect the ionic charge states as a function of energy (see e.g., Kovaltsov et al 2001;Klecker et al 2007). …”

Section: Ionic Charge States In Gradual Sepsmentioning

confidence: 99%

Large gradual solar energetic particle events

Desai

Giacalone

2016

Living Rev. Sol. Phys.

401

305

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Solar energetic particles, or SEPs, from suprathermal (few keV) up to relativistic (∼few GeV) energies are accelerated near the Sun in at least two ways: (1) by magnetic reconnection-driven processes during solar flares resulting in impulsive SEPs, and (2) at fast coronal-mass-ejection-driven shock waves that produce large gradual SEP events. Large gradual SEP events are of particular interest because the accompanying high-energy (>10s MeV) protons pose serious radiation threats to human explorers living and working beyond low-Earth orbit and to technological assets such as communications and scientific satellites in space. However, a complete understanding of these large SEP events has eluded us primarily because their properties, as observed in Earth orbit, are smeared due to mixing and contributions from many important physical effects. This paper provides a comprehensive review of the current state of knowledge of these important phenomena, and summarizes some of the key questions that will be addressed by two upcoming missions-NASA's Solar Probe Plus and ESA's Solar Orbiter. Both of these missions are designed to directly and repeatedly sample the near-Sun environments where interplanetary scattering and transport effects are significantly reduced, allowing us to discriminate between different acceleration sites and mechanisms and to isolate the contributions of numerous physical processes occurring during large SEP events.

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Section: Ionic Charge States In Gradual Sepsmentioning

confidence: 99%

Large gradual solar energetic particle events

Desai

Giacalone

2016

Living Rev. Sol. Phys.

401

305

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“…In these models, the large variability of the increase of Q with energy can be reproduced by variable acceleration rates and non-equilibrium conditions for charge stripping (e.g. Kovaltsov et al, 2001). In the case of near-equilibrium conditions (as observed in the 6 November, 1997 event) and acceleration time scales of ∼1-100 seconds, this corresponds to coronal densities of 10 8 -10 10 cm −3 , i.e.…”

Section: Ionic Charge Composition In Interplanetary Shock-related Eventsmentioning

confidence: 98%

Energetic Particle Observations

et al. 2006

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The characteristics of solar energetic particles (SEP) as observed in interplanetary space provide fundamental information about the origin of these particles, and the acceleration and propagation processes at the Sun and in interplanetary space. Furthermore, energetic particles provide information on the development and structure of coronal mass ejections as they propagate from the solar corona into the interplanetary medium. In this paper we review the measurements of energetic particles in interplanetary space and discuss their implication for our understanding of the sources, and of acceleration and propagation processes.

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“…The amount of electron stripping depends on the product of the density in the acceleration region (n) and the acceleration time ('r). To strip MeV/nucleon Fe requires m ::::<10 10 s/cm 3 (Kovaltsov et al, 2001). However, there is a correlation between the Fe/O ratio and the mean charge state of Fe (Moebius et al, 2000;Labrador et al, 2003), as shown in Figure 4.…”

Section: New Observations Of Impulsive and Gradual Eventsmentioning

confidence: 99%

“…Perhaps high-energy particles traverse more material during acceleration and are stripped of additional electrons (Ruffolo, 1997, Reames, Ng, and 1jJlka, 1999, Barghouty and Mewaldt, 2000Kocharov, Kovaltsov, and Torsti, 2001). The amount of electron stripping depends on the product of the density in the acceleration region (n) and the acceleration time ('r).…”

Section: New Observations Of Impulsive and Gradual Eventsmentioning

confidence: 99%

The Source Material for Large Solar Energetic Particle Events

Mewaldt

Cohen

Mason

2006

Solar Eruptions and Energetic Particles

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We review evidence regarding the origin of material accelerated in large, gradual solar energetic particle (SEP) events. According to the two-class paradigm in place at the start of solar cycle 23, impulsive SEP events accelerate heated flare material, while gradual SEP events are accelerated out of the solar wind by shocks driven by fast coronal mass ejections (CMEs). However, new data from solar cycle 23 has shown that the energetic ions in gradual events often include composition signatures associated with impulsive events, including emichments in 3 He, heavy elements such as Fe, and ionic charge states indicative of~ 10 MK temperatures. In addition, gradual SEP events differ in composition from bulk solar wind in several key respects, implying that solar wind is not the principal seed population for these events. Several lines of evidence show that CME-driven shocks accelerate principally suprathennal ions with velocities several times that of the solar wind. The suprathermal pool incorporates ions from impulsive solar flares and previous gradual events, CIR events, pickup ions, CME ejecta, and the suprathermal tail of the solar wind. This paper reviews evidence for the sources of ions accelerated in gradual SEP events, considers the composition and available densities of suprathermal ions, and describes models that attempt to account for the surprisingly variable composition of gradual SEP events. We find that below ~1 MeV/nucleon almost all events are Fe-rich compared to the average 5 to 12 MeV/nucleon SEP composition. Iron-rich SEP events above 10 Me V /nucleon occur mainly dming periods when the intensity of suprathermal iron in the inner heliosphere is high, due mainly to previous gradual events.

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Charge-equilibration of Fe ions accelerated in a hot plasma

Cited by 28 publications

References 24 publications

Large gradual solar energetic particle events

Large gradual solar energetic particle events

Energetic Particle Observations

The Source Material for Large Solar Energetic Particle Events

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