SHORT ACCELERATION TIMES FROM SUPERDIFFUSIVE SHOCK ACCELERATION IN THE HELIOSPHERE
Abstract
The analysis of time profiles of particles accelerated at interplanetary shocks allows particle transport properties to be inferred. The frequently observed powerlaw decay upstream, indeed, implies a superdiffusive particle transport when the level of magnetic field variance does not change as the time interval from the shock front increases. In this context, a superdiffusive shock acceleration (SSA) theory has been developed, allowing us to make predictions of the acceleration times. In this work we estimate for a number of interplanetary shocks, including the solar wind termination shock, the acceleration times for energetic protons in the framework of SSA and we compare the results with the acceleration times predicted by standard diffusive shock acceleration. The acceleration times due to SSA are found to be much shorter than in the classical model, and also shorter than the interplanetary shock lifetimes. This decrease of the acceleration times is due to the scalefree nature of the particle displacements in the framework of superdiffusion. Indeed, very long displacements are possible, increasing the probability for particles far from the front of the shock to return, and short displacements have a high probability of occurrence, increasing the chances for particles close to the front to cross themore »
 Authors:
 Dipartimento di Fisica, Università della Calabria, Ponte P. Bucci, I87036 Rende (Italy)
 Publication Date:
 OSTI Identifier:
 22521778
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Astrophysical Journal; Journal Volume: 815; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; CHARGEDPARTICLE TRANSPORT; COMPARATIVE EVALUATIONS; DIFFUSION; HELIOSPHERE; LIFETIME; MAGNETIC FIELDS; PROBABILITY; SHOCK WAVES; SOLAR PROTONS; SOLAR WIND
Citation Formats
Perri, S., and Zimbardo, G., Email: silvia.perri@fis.unical.it. SHORT ACCELERATION TIMES FROM SUPERDIFFUSIVE SHOCK ACCELERATION IN THE HELIOSPHERE. United States: N. p., 2015.
Web. doi:10.1088/0004637X/815/1/75.
Perri, S., & Zimbardo, G., Email: silvia.perri@fis.unical.it. SHORT ACCELERATION TIMES FROM SUPERDIFFUSIVE SHOCK ACCELERATION IN THE HELIOSPHERE. United States. doi:10.1088/0004637X/815/1/75.
Perri, S., and Zimbardo, G., Email: silvia.perri@fis.unical.it. 2015.
"SHORT ACCELERATION TIMES FROM SUPERDIFFUSIVE SHOCK ACCELERATION IN THE HELIOSPHERE". United States.
doi:10.1088/0004637X/815/1/75.
@article{osti_22521778,
title = {SHORT ACCELERATION TIMES FROM SUPERDIFFUSIVE SHOCK ACCELERATION IN THE HELIOSPHERE},
author = {Perri, S. and Zimbardo, G., Email: silvia.perri@fis.unical.it},
abstractNote = {The analysis of time profiles of particles accelerated at interplanetary shocks allows particle transport properties to be inferred. The frequently observed powerlaw decay upstream, indeed, implies a superdiffusive particle transport when the level of magnetic field variance does not change as the time interval from the shock front increases. In this context, a superdiffusive shock acceleration (SSA) theory has been developed, allowing us to make predictions of the acceleration times. In this work we estimate for a number of interplanetary shocks, including the solar wind termination shock, the acceleration times for energetic protons in the framework of SSA and we compare the results with the acceleration times predicted by standard diffusive shock acceleration. The acceleration times due to SSA are found to be much shorter than in the classical model, and also shorter than the interplanetary shock lifetimes. This decrease of the acceleration times is due to the scalefree nature of the particle displacements in the framework of superdiffusion. Indeed, very long displacements are possible, increasing the probability for particles far from the front of the shock to return, and short displacements have a high probability of occurrence, increasing the chances for particles close to the front to cross the shock many times.},
doi = {10.1088/0004637X/815/1/75},
journal = {Astrophysical Journal},
number = 1,
volume = 815,
place = {United States},
year = 2015,
month =
}

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