Ion acceleration at CME-driven shocks near the Earth and the Sun

Journal Article · Tue Nov 20 00:00:00 EST 2012 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.4768748· OSTI ID:22075838

Desai, Mihir; Dayeh, Maher; Ebert, Robert; Smith, Charles; Mason, Glenn; Li, G ^[1]

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1. Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas, 78238 (United States)

We compare the behavior of heavy ion spectra during an Energetic Storm Particle (ESP) event that exhibited clear evidence of wave excitation with that observed during an intense, large gradual Solar Energetic Particle (SEP) event in which the associated <0.2 MeV/nucleon ions are delayed >12 hr. We interpret that the ESP event is an example of the first-order Fermi acceleration process where enhancements in the magnetic field power spectral densities around local ion cyclotron frequency {nu}{sub pc} indicate the presence of Alfven waves excited by accelerated protons streaming away from the in-situ interplanetary shock. The softening or unfolding of the CNO energy spectrum below {approx}200 keV/nucleon and the systematic organization of the Fe and O spectral roll-overs with the E/q ratio during the ESP event are likely due to M/Q-dependent trapping and scattering of the heavy ions by the proton-excited waves. Based on striking similarities in the spectral behavior observed upstream of both, the ESP and the SEP event, we suggest that coupling between proton-generated Alfven waves and energetic ions is also operating at the distant CME shock during the large, gradual SEP event, thereby providing us with a new, powerful tool to remotely probe the roles of shock geometries and wave-particle interactions at near-Sun CME-driven shocks.

• OSTI ID: 22075838
• Journal Information: AIP Conference Proceedings, Vol. 1500, Issue 1; Conference: 11. annual international astrophysics conference, Palm Springs, CA (United States), 19-23 Mar 2012; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCELERATION
ALFVEN WAVES
ASTROPHYSICS
CNO CYCLE
COMPARATIVE EVALUATIONS
COUPLING
CYCLOTRON FREQUENCY
EXCITATION
INTERPLANETARY MAGNETIC FIELDS
PARTICLE INTERACTIONS
PLASMA
SHOCK WAVES
SOLAR PROTONS
SOLAR WIND
SPECTRAL DENSITY
SUN
TAIL IONS
TRAPPING