Magnetic Field Line Random Walk and Solar Energetic Particle Path Lengths: Stochastic Theory and PSP/ISoIS Observation
| dc.contributor.author | Chhiber, R. | |
| dc.contributor.author | Matthaeus, W. H. | |
| dc.contributor.author | Cohen, C.M.S. | |
| dc.contributor.author | Ruffolo, D. | |
| dc.contributor.author | Goldstein, Melvyn | |
| dc.contributor.author | et al | |
| dc.date.accessioned | 2020-12-10T19:42:13Z | |
| dc.date.available | 2020-12-10T19:42:13Z | |
| dc.description | Authors: R. Chhiber, W. H. Matthaeus, C. M. S. Cohen, D. Ruffolo, W. Sonsrettee, P. Tooprakai, A. Seripienlert, P. Chuychai, A. V. Usmanov, M. L. Goldstein, D. J. McComas, R. A. Leske, J. R. Szalay, C. J. Joyce, A. C. Cummings, E. C. Roelof, E. R. Christian, R. A. Mewaldt, A. W. Labrador, J. Giacalone, N. A. Schwadron, D. G. Mitchell, M. E. Hill, M. E. Wiedenbeck, R. L. McNutt Jr. and M. I. Desai | |
| dc.description.abstract | Context:In 2020 May-June, six solar energetic ion events were observed by the Parker Solar Probe/ISoIS instrument suite at 0.35 AU from the Sun. From standard velocity-dispersion analysis, the apparent ion path length is 0.625 AU at the onset of each event. Aims:We develop a formalism for estimating the path length of random-walking magnetic field lines, to explain why the apparent ion pathlength at event onset greatly exceeds the radial distance from the Sun for these events. Methods:We developed analytical estimates of the average increase in pathlength of random-walking magnetic field lines, relative to the unperturbed mean field. Monte Carlo simulations of fieldline and particle trajectories in a model of solar wind turbulence are used to validate the formalism and study the path lengths of particle guiding-center and full-orbital trajectories. The formalism is implemented in a global solar wind model, and results are compared with ion pathlengths inferred from ISoIS observations. Results:Both a simple estimate and a rigorous theoretical formulation are obtained for fieldlines' pathlength increase as a function of pathlength along the large-scale field. From simulated fieldline and particle trajectories, we find that particle guiding centers can have pathlengths somewhat shorter than the average fieldline pathlength, while particle orbits can have substantially larger pathlengths due to their gyromotion with a nonzero effective pitch angle. Conclusions:The long apparent path length during these solar energetic ion events can be explained by 1) a magnetic field line path length increase due to the field line random walk, and 2) particle transport about the guiding center with a nonzero effective pitch angle. Our formalism for computing the magnetic field line path length, accounting for turbulent fluctuations, may be useful for application to solar particle transport in general. | en_US |
| dc.description.sponsorship | We thank Junxiang Hu for useful discussions. This research is partially supported by the Parker Solar Probe mission and the IS IS project (contract NNN06AA01C) and a subcontract to University of Delaware from Princeton University (SUB0000165). Additional support is acknowledged from the NASA Living With a Star (LWS) program (NNX17AB79G) and HSR program (80NSSC18K1210 & 80NSSC18K1648) and Thailand Science Research and Innovation (RTA6280002). The IS IS data and visualization tools are available to the community at https://spacephysics.princeton.edu/missions-instruments/isois; data are also available via the NASA Space Physics Data Facility. PSP was designed, built, and is now operated by the Johns Hopkins Applied Physics Laboratory as part of NASA’s LWS program (contract NNN06AA01C). Support from the LWS management and technical team has played a critical role in the success of the PSP mission. | en_US |
| dc.description.uri | https://www.aanda.org/articles/aa/full_html/2021/06/aa39816-20/aa39816-20.html | en_US |
| dc.format.extent | 10 pages | en_US |
| dc.genre | journal articles | en_US |
| dc.identifier | doi:10.13016/m2huwx-leit | |
| dc.identifier.citation | “Magnetic Field Line Random Walk and Solar Energetic Particle Path Lengths: Stochastic Theory and PSP/ISIS Observations”, R. Chhiber, W.H. Matthaeus, C.M.S. Cohen, D. Ruffolo, W. Sonsrettee, P. Tooprakai, A. Seripienlert, P. Chuychai, A.V. Usmanov, M.L. Goldstein, D.J. McComas, R.A. Leske, J.R. Szalay, C.J. Joyce, A.C. Cummings, E.C. Roelof, E.R. Christian, R.A. Mewaldt, A.W. Labrador, J. Giacalone, N.A. Schwadron, D.G. Mitchell, M.E. Hill, M.E. Wiedenbeck, R.L. McNutt Jr., M.I. Desai, Astronomy and Astrophysics, 650, A26 (2021) https://doi.org/10.1051/0004-6361/202039816. | en_US |
| dc.identifier.uri | http://hdl.handle.net/11603/20232 | |
| dc.identifier.uri | https://doi.org/10.1051/0004-6361/202039816 | |
| dc.language.iso | en_US | en_US |
| dc.publisher | EDP Sciences | |
| dc.relation.isAvailableAt | The University of Maryland, Baltimore County (UMBC) | |
| dc.relation.ispartof | UMBC Goddard Planetary Heliophysics Institute (GPHI) | |
| dc.relation.ispartof | UMBC Staff Collection | |
| dc.rights | Public Domain Mark 1.0 | * |
| dc.rights | This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law. | |
| dc.rights.uri | http://creativecommons.org/publicdomain/mark/1.0/ | * |
| dc.title | Magnetic Field Line Random Walk and Solar Energetic Particle Path Lengths: Stochastic Theory and PSP/ISoIS Observation | en_US |
| dc.type | Text | en_US |
| dcterms.creator | https://orcid.org/0000-0002-5317-988X |