Mazur, J. E. and Mason, G. M. and Dwyer, J. R. and Giacalone, J. and Jokipii, J. R. and Stone, E. C. (2000) The mixing of interplanetary magnetic field lines: A significant transport effect in studies of the energy spectra of impulsive flares. In: Acceleration and Transport of Energetic Particles Observed in the Heliosphere. AIP Conference Proceedings. No.528. American Institute of Physics , Melville, New York, pp. 47-54. ISBN 1-56396-951-3 http://resolver.caltech.edu/CaltechAUTHORS:20111201-093719145
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Using instrumentation on board the ACE spacecraft we describe short-time scale (~3 hour) variations observed in the arrival profiles of ~20 keV nucleon^(–1) to ~2 MeV nucleon^(–1) ions from impulsive solar flares. These variations occurred simultaneously across all energies and were generally not in coincidence with any local magnetic field or plasma signature. These features appear to be caused by the convection of magnetic flux tubes past the observer that are alternately filled and devoid of flare ions even though they had a common flare source at the Sun. In these particle events we therefore have a means to observe and measure the mixing of the interplanetary magnetic field due to random walk. In a survey of 25 impulsive flares observed at ACE between 1997 November and 1999 July these features had an average time scale of 3.2 hours, corresponding to a length of ~0.03 AU. The changing magnetic connection to the flare site sometimes lead to an incomplete observation of a flare at 1 AU; thus the field-line mixing is an important effect in studies of impulsive flare energy spectra.
|Item Type:||Book Section|
|Additional Information:||© 2000 American Institute of Physics. Issue Date: 15 September 2000. We thank the many members of the ACE instrument teams who have contributed to the success of the ACE mission, and acknowledge the special efforts of R. E. Gold and S. M. Krimigis. We thank C. Smith and the ACE/MAG team for the ACE magnetic field measurements reported here, and D. McComas, R. Skoug, and the ACE/SWEPAM team for solar wind measurements used in the analysis. Contract number Q295801 between the University of Maryland and The Aerospace Corporation supported this work.|
|Group:||Space Radiation Laboratory|
|Subject Keywords:||solar radiation; solar flares; solar wind; astrophysical plasma; solar cosmic ray particles; cosmic ray propagation; transport processes; interplanetary magnetic fields; magnetic field effects; magnetic flux|
|Classification Code:||PACS: 96.50.Bh; 96.40.Fg; 96.60.Rd; 95.85.Ry|
|Official Citation:||The mixing of interplanetary magnetic field lines: A significant transport effect in studies of the energy spectra of impulsive flares J. E. Mazur, G. M. Mason, J. R. Dwyer, J. Giacalone, J. R. Jokipii, and E. C. Stone, AIP Conf. Proc. 528, 47 (2000), DOI:10.1063/1.1324280|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||01 Dec 2011 21:12|
|Last Modified:||26 Dec 2012 14:33|
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