Enhanced Abundances of ^3He in Large Solar Energetic Particle Events
Abstract
Observations of a number of relatively large solar energetic particle (SEP) events that have occurred since the launch of ACE in August 1997 have shown that the ratio of ^3He/^4He can be enhanced over the solar wind value (~4×10^(–4)) by more than an order of magnitude in such events. Since particle acceleration in these "gradual" SEP events is thought to be caused by CME-driven shocks traveling through the solar corona and interplanetary medium, a source of ^3He in addition to the solar wind appears required to provide the seed material. Using data from the Solar Isotope Spectrometer on ACE, we have carried out a more detailed investigation of the characteristics of the ^3He enhancements at energies >5 MeV/nucleon in three large SEP events (4 Nov 1997, 6 May 1998, and 14 Nov 1998). We find that the ^3He/^4He ratios are essentially time-independent during the events, that the ^3He energy spectra are markedly harder than those commonly observed in impulsive events, and that the spectra of ^3He may be harder than those of ^4He.
Additional Information
© 2000 American Institute of Physics. Issue Date: 15 September 2000. This research was supported by the National Aeronautics and Space Administration at the California Institute of Technology (under grant NAG5-6912), the Jet Propulsion Laboratory, and the Goddard Space Flight Center.Attached Files
Published - WIEaipcp00b.pdf
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Additional details
- Eprint ID
- 28482
- Resolver ID
- CaltechAUTHORS:20111216-080137898
- NASA/Caltech
- NAG5-6912
- JPL
- Goddard Space Flight Center
- Created
-
2011-12-16Created from EPrint's datestamp field
- Updated
-
2021-11-09Created from EPrint's last_modified field
- Caltech groups
- Space Radiation Laboratory
- Series Name
- AIP Conference Proceedings
- Series Volume or Issue Number
- 528
- Other Numbering System Name
- Space Radiation Laboratory
- Other Numbering System Identifier
- 2000-21