Perpendicular transport of low-energy corotating interaction region-associated nuclei

J. R. Dwyer; G. M. Mason; J. E. Mazur; J. R. Jokipii; T. T. Von Rosenvinge; R. P. Lepping

doi:10.1086/311003

Perpendicular transport of low-energy corotating interaction region-associated nuclei

J. R. Dwyer, G. M. Mason, J. E. Mazur, J. R. Jokipii, T. T. Von Rosenvinge, R. P. Lepping

Lunar and Planetary Lab

Research output: Contribution to journal › Article › peer-review

84 Scopus citations

Abstract

We present compelling observational evidence for substantial transport of energetic charged particles across the local average magnetic field. Using data from the STEP/EPACT instrument on board the Wind spacecraft, we find that during three intense corotating interaction region (CIR) events, for periods greater than 12 hr, the observed anisotropy of the particle intensity at 1 AU is often directed at a significant angle to the measured magnetic field direction, which implies significant transport across the local magnetic field. A simple diffusion model is found to fit the three events very well with a large inferred κ_⊥/κ_∥ . For example, for 80-154 keV nucleon^-1 helium, we find that κ_⊥/κ_∥ = 1.47 ± 0.07, κ_⊥!κ_∥ = 0.13 ± 0.02, and κ_⊥/κ_∥ = 0.45 ± 0.05 for the most intense periods of the three events. We believe that this is the first direct, quantitative measurement in space of large cross-field particle transport, utilizing simultaneous measurements of the streaming particle flux, the solar wind velocity and the magnetic field direction.

Original language	English (US)
Pages (from-to)	L115-L118
Journal	Astrophysical Journal
Volume	490
Issue number	1 PART II
DOIs	https://doi.org/10.1086/311003
State	Published - 1997

Keywords

Cosmic rays
Diffusion
Interplanetary medium
Magnetic fields
Solar wind

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1086/311003

Cite this

@article{ad81377a07404decbd6f831bd636178c,

title = "Perpendicular transport of low-energy corotating interaction region-associated nuclei",

abstract = "We present compelling observational evidence for substantial transport of energetic charged particles across the local average magnetic field. Using data from the STEP/EPACT instrument on board the Wind spacecraft, we find that during three intense corotating interaction region (CIR) events, for periods greater than 12 hr, the observed anisotropy of the particle intensity at 1 AU is often directed at a significant angle to the measured magnetic field direction, which implies significant transport across the local magnetic field. A simple diffusion model is found to fit the three events very well with a large inferred κ⊥/κ∥ . For example, for 80-154 keV nucleon-1 helium, we find that κ⊥/κ∥ = 1.47 ± 0.07, κ⊥!κ∥ = 0.13 ± 0.02, and κ⊥/κ∥ = 0.45 ± 0.05 for the most intense periods of the three events. We believe that this is the first direct, quantitative measurement in space of large cross-field particle transport, utilizing simultaneous measurements of the streaming particle flux, the solar wind velocity and the magnetic field direction.",

keywords = "Cosmic rays, Diffusion, Interplanetary medium, Magnetic fields, Solar wind",

author = "Dwyer, {J. R.} and Mason, {G. M.} and Mazur, {J. E.} and Jokipii, {J. R.} and {Von Rosenvinge}, {T. T.} and Lepping, {R. P.}",

note = "Funding Information: We thank the members of the Space Physics Group, Department of Physics at the University of Maryland, and the EPACT instrument team, Goddard Space Flight Center, for the construction of the instrumentation. We thank K. W. Ogilvie, R. B. Torbert, and A. J. Lazarus for the SWE solar wind data cited here. This work was supported in part by NASA contract NAS5-30927 and grant NAG 5-2865. The work of J. R. J. was supported in part by the National Science Foundation under grant ATM 9616547 and by the National Aeronautics and Space Administration under grants NAG 2251 and NAGW 1931.",

year = "1997",

doi = "10.1086/311003",

language = "English (US)",

volume = "490",

pages = "L115--L118",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "1 PART II",

}

TY - JOUR

T1 - Perpendicular transport of low-energy corotating interaction region-associated nuclei

AU - Dwyer, J. R.

AU - Mason, G. M.

AU - Mazur, J. E.

AU - Jokipii, J. R.

AU - Von Rosenvinge, T. T.

AU - Lepping, R. P.

N1 - Funding Information: We thank the members of the Space Physics Group, Department of Physics at the University of Maryland, and the EPACT instrument team, Goddard Space Flight Center, for the construction of the instrumentation. We thank K. W. Ogilvie, R. B. Torbert, and A. J. Lazarus for the SWE solar wind data cited here. This work was supported in part by NASA contract NAS5-30927 and grant NAG 5-2865. The work of J. R. J. was supported in part by the National Science Foundation under grant ATM 9616547 and by the National Aeronautics and Space Administration under grants NAG 2251 and NAGW 1931.

PY - 1997

Y1 - 1997

N2 - We present compelling observational evidence for substantial transport of energetic charged particles across the local average magnetic field. Using data from the STEP/EPACT instrument on board the Wind spacecraft, we find that during three intense corotating interaction region (CIR) events, for periods greater than 12 hr, the observed anisotropy of the particle intensity at 1 AU is often directed at a significant angle to the measured magnetic field direction, which implies significant transport across the local magnetic field. A simple diffusion model is found to fit the three events very well with a large inferred κ⊥/κ∥ . For example, for 80-154 keV nucleon-1 helium, we find that κ⊥/κ∥ = 1.47 ± 0.07, κ⊥!κ∥ = 0.13 ± 0.02, and κ⊥/κ∥ = 0.45 ± 0.05 for the most intense periods of the three events. We believe that this is the first direct, quantitative measurement in space of large cross-field particle transport, utilizing simultaneous measurements of the streaming particle flux, the solar wind velocity and the magnetic field direction.

AB - We present compelling observational evidence for substantial transport of energetic charged particles across the local average magnetic field. Using data from the STEP/EPACT instrument on board the Wind spacecraft, we find that during three intense corotating interaction region (CIR) events, for periods greater than 12 hr, the observed anisotropy of the particle intensity at 1 AU is often directed at a significant angle to the measured magnetic field direction, which implies significant transport across the local magnetic field. A simple diffusion model is found to fit the three events very well with a large inferred κ⊥/κ∥ . For example, for 80-154 keV nucleon-1 helium, we find that κ⊥/κ∥ = 1.47 ± 0.07, κ⊥!κ∥ = 0.13 ± 0.02, and κ⊥/κ∥ = 0.45 ± 0.05 for the most intense periods of the three events. We believe that this is the first direct, quantitative measurement in space of large cross-field particle transport, utilizing simultaneous measurements of the streaming particle flux, the solar wind velocity and the magnetic field direction.

KW - Cosmic rays

KW - Diffusion

KW - Interplanetary medium

KW - Magnetic fields

KW - Solar wind

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JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1 PART II

ER -

Perpendicular transport of low-energy corotating interaction region-associated nuclei

Abstract

Keywords

ASJC Scopus subject areas

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