Interplanetary ions during an energetic storm particle event: The distribution function from solar wind thermal energies to 1.6 MeV

Gosling, J. T.; Asbridge, J. R.; Bame, S. J.; Feldman, W. C.; Zwickl, R. D.; Paschmann, G.; Sckopke, N.; Hynds, R. J.

doi:10.1029/ja086ia02p00547

Cited by 264 publications

(127 citation statements)

References 40 publications

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“…The spectra are examined at the time of shock passage, which is one way to isolate the issue of acceleration from that of transport. They confirm a well-known rollover in the spectrum at 0.1-10 MeV nucleon −1 (see also Gosling, Asbridge, Bame, et al 1981;van Nes, Reinhard, Sanderson, et al 1985), where the power-law spectrum in particle energy changes to decline more rapidly above a critical energy, T c . Such spectra are typically modeled empirically using the spectral form of Ellison & Ramaty (1985) for T c as a fit parameter.…”

Section: Transport Perpendicular To the Mean Magnetic Fieldsupporting

confidence: 66%

Transport and Acceleration of Solar Energetic Particles from Coronal Mass Ejection Shocks

Ruffolo¹

2004

Proc. IAU

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Abstract. After a brief overview of solar energetic particle (SEP) emission from coronal mass ejection (CME) shocks, we turn to a discussion of their transport and acceleration. The high energy SEP are accelerated near the Sun, and because of their well-known source location, their transport can be modeled quantitatively to obtain precise information on the injection function (number of particles emitted vs. time), including a determination of the onset time to within 1 min. For certain events, transport modeling also indicates magnetic topology with mirroring or closed field loops. Important progress has also been made on the transport of low energy SEP from very strong events, which can display exhibit interesting saturation effects and compositional variations. The acceleration of SEP by CME-driven shocks in the interplanetary medium is attributed to diffusive shock acceleration, but the spectrum of SEP production is typically modeled empirically. Recent progress has largely focused on using detailed composition measurements to determine fractionation effects of shock acceleration and even to clarify the nature of the seed population. In particular, there are many indications that the seed population is suprathermal (pre-energized) and the injection problem is not relevant to acceleration at interplanetary CME-driven shocks. We argue that the finite time available for shock acceleration provides the best explanation of the high-energy rollover.

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Section: Transport Perpendicular To the Mean Magnetic Fieldsupporting

confidence: 66%

Transport and Acceleration of Solar Energetic Particles from Coronal Mass Ejection Shocks

Ruffolo¹

2004

Proc. IAU

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“…Berdichevsky et al 2000). Gosling et al (1981) first showed that the low-energy spectrum of accelerated particles forms a continuum with the spectrum of the seed population in the solar wind, from which it is primarily derived. Desai et al (2003) showed that lowenergy ion abundances near the shock peak were much more closely correlated with ambient abundances upstream of the shock than with the abundance of the corresponding elements in the solar wind, as expected from our discussion of the seed population in Section 2.…”

Section: Interplanetary Shocksmentioning

confidence: 99%

The Two Sources of Solar Energetic Particles

2013

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Abstract. Evidence for two different physical mechanisms for acceleration of solar energetic particles (SEPs) arose 50 years ago with radio observations of type III bursts, produced by outward streaming electrons, and type II bursts from coronal and interplanetary shock waves. Since that time we have found that the former are related to "impulsive" SEP events from impulsive flares or jets. Here, resonant stochastic acceleration, related to magnetic reconnection involving open field lines, produces not only electrons but 1000-fold enhancements of 3 He/ 4 He and of (Z>50)/O. Alternatively, in "gradual" SEP events, shock waves, driven out from the Sun by coronal mass ejections (CMEs), more democratically sample ion abundances that are even used to measure the coronal abundances of the elements. Gradual events produce by far the highest SEP intensities near Earth. Sometimes residual impulsive suprathermal ions contribute to the seed population for shock acceleration, complicating the abundance picture, but this process has now been modeled theoretically. Initially, impulsive events define a point source on the Sun, selectively filling few magnetic flux tubes, while gradual events show extensive acceleration that can fill half of the inner heliosphere, beginning when the shock reaches ~2 solar radii. Shock acceleration occurs as ions are scattered back and forth across the shock by resonant Alfvén waves amplified by the accelerated protons themselves as they stream away. These waves also can produce a streaming-limited maximum SEP intensity and plateau region upstream of the shock. Behind the shock lies the large expanse of the "reservoir", a spatially extensive trapped volume of uniform SEP intensities with invariant energy-spectral shapes where overall intensities decrease with time as the enclosing "magnetic bottle" expands adiabatically. These reservoirs now explain the slow intensity decrease that defines gradual events and was once erroneously attributed solely to slow outward diffusion of the particles. At times the reservoir from one event can contribute its abundances and even its spectra as a seed population for acceleration by a second CME-driven shock wave. Confinement of particles to magnetic flux tubes that thread their source early in events is balanced at late times by slow velocity-dependent migration through a tangled network produced by field-line random walk that is probed by SEPs from both impulsive and gradual events and even by anomalous cosmic rays from the outer heliosphere. As a practical consequence, high-energy protons from gradual SEP events can be a significant radiation hazard to astronauts and equipment in space and to the passengers of high-altitude aircraft flying polar routes.

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“…Observations of charged particles in the solar wind show that the velocity distribution functions (VDF) associated with these particles feature suprathermal components (Feldman et al 1975;Gosling et al 1981;Armstrong et al 1983). For a high energy regime these VDFs can be characterized by a velocity power-law tail, .…”

Section: Introductionmentioning

confidence: 99%

Solar Wind Electron Acceleration via Langmuir Turbulence

Yoon¹,

Ziebell²,

Gaelzer³

et al. 2013

Terr. Atmos. Ocean. Sci.

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The solar wind electrons observed at 1 AU are characterized by velocity distribution functions (VDF) that deviate from the Maxwellian form in a high energy regime. Such a feature is often modeled by a kappa distribution. In the present paper a self-consistent theory of quiet-time solar wind electrons that contain a power-law tail component, ,is discussed. These electrons are assumed to be in dynamic equilibrium with enhanced electrostatic fluctuations with peak frequency near the plasma frequency (i.e., the Langmuir turbulence). In order to verify the theoretical prediction, the solar wind electrons in the high-energy range known as the super-halo distribution detected by WIND and STEREO spacecraft are compared against the theoretical model where it was found that the theoretical power-law index is intermittent with regard to the observed range of indices, thus indicating that the turbulent equilibrium model of suprathermal solar wind electrons may be valid.

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Interplanetary ions during an energetic storm particle event: The distribution function from solar wind thermal energies to 1.6 MeV

Cited by 264 publications

References 40 publications

Transport and Acceleration of Solar Energetic Particles from Coronal Mass Ejection Shocks

Transport and Acceleration of Solar Energetic Particles from Coronal Mass Ejection Shocks

The Two Sources of Solar Energetic Particles

Solar Wind Electron Acceleration via Langmuir Turbulence

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