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Title: Heliospheric current sheet and effects of its interaction with solar cosmic rays

Abstract

The effects of interaction of solar cosmic rays (SCRs) with the heliospheric current sheet (HCS) in the solar wind are analyzed. A self-consistent kinetic model of the HCS is developed in which ions with quasiadiabatic dynamics can present. The HCS is considered an equilibrium embedded current structure in which two main plasma species with different temperatures (the low-energy background plasma of the solar wind and the higher energy SCR component) contribute to the current. The obtained results are verified by comparing with the results of numerical simulations based on solving equations of motion by the particle tracing method in the given HCS magnetic field with allowance for SCR particles. It is shown that the HCS is a relatively thin multiscale current configuration embedded in a thicker plasma layer. In this case, as a rule, the shear (tangential to the sheet current) component of the magnetic field is present in the HCS. Taking into account high-energy SCR particles in the HCS can lead to a change of its configuration and the formation of a multiscale embedded structure. Parametric family of solutions is considered in which the current balance in the HCS is provided at different SCR temperatures and different densities ofmore » the high-energy plasma. The SCR densities are determined at which an appreciable (detectable by satellites) HCS thickening can occur. Possible applications of this modeling to explain experimental observations are discussed.« less

Authors:
 [1]; ; ; ;  [2]
  1. Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)
  2. Russian Academy of Sciences, Space Research Institute (Russian Federation)
Publication Date:
OSTI Identifier:
22614096
Resource Type:
Journal Article
Resource Relation:
Journal Name: Plasma Physics Reports; Journal Volume: 42; Journal Issue: 8; Other Information: Copyright (c) 2016 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COMPUTERIZED SIMULATION; COSMIC RADIATION; CURRENTS; EQUATIONS OF MOTION; HELIOSPHERE; INTERACTIONS; KINETICS; MAGNETIC FIELDS; MATHEMATICAL SOLUTIONS; PLASMA DENSITY; SHEAR; SOLAR WIND

Citation Formats

Malova, H. V., E-mail: hmalova@yandex.ru, Popov, V. Yu., Grigorenko, E. E., Dunko, A. V., and Petrukovich, A. A. Heliospheric current sheet and effects of its interaction with solar cosmic rays. United States: N. p., 2016. Web. doi:10.1134/S1063780X16080079.
Malova, H. V., E-mail: hmalova@yandex.ru, Popov, V. Yu., Grigorenko, E. E., Dunko, A. V., & Petrukovich, A. A. Heliospheric current sheet and effects of its interaction with solar cosmic rays. United States. doi:10.1134/S1063780X16080079.
Malova, H. V., E-mail: hmalova@yandex.ru, Popov, V. Yu., Grigorenko, E. E., Dunko, A. V., and Petrukovich, A. A. 2016. "Heliospheric current sheet and effects of its interaction with solar cosmic rays". United States. doi:10.1134/S1063780X16080079.
@article{osti_22614096,
title = {Heliospheric current sheet and effects of its interaction with solar cosmic rays},
author = {Malova, H. V., E-mail: hmalova@yandex.ru and Popov, V. Yu. and Grigorenko, E. E. and Dunko, A. V. and Petrukovich, A. A.},
abstractNote = {The effects of interaction of solar cosmic rays (SCRs) with the heliospheric current sheet (HCS) in the solar wind are analyzed. A self-consistent kinetic model of the HCS is developed in which ions with quasiadiabatic dynamics can present. The HCS is considered an equilibrium embedded current structure in which two main plasma species with different temperatures (the low-energy background plasma of the solar wind and the higher energy SCR component) contribute to the current. The obtained results are verified by comparing with the results of numerical simulations based on solving equations of motion by the particle tracing method in the given HCS magnetic field with allowance for SCR particles. It is shown that the HCS is a relatively thin multiscale current configuration embedded in a thicker plasma layer. In this case, as a rule, the shear (tangential to the sheet current) component of the magnetic field is present in the HCS. Taking into account high-energy SCR particles in the HCS can lead to a change of its configuration and the formation of a multiscale embedded structure. Parametric family of solutions is considered in which the current balance in the HCS is provided at different SCR temperatures and different densities of the high-energy plasma. The SCR densities are determined at which an appreciable (detectable by satellites) HCS thickening can occur. Possible applications of this modeling to explain experimental observations are discussed.},
doi = {10.1134/S1063780X16080079},
journal = {Plasma Physics Reports},
number = 8,
volume = 42,
place = {United States},
year = 2016,
month = 8
}
  • We discuss the role which empirical determinations of the latitude variation of cosmic rays with respect to the current sheet may have in illuminating the importance of the cross-field drift of particles in the large-scale heliospheric magnetic field. Using K coronameter observation and measured solar wind speeds, we have determined the latitude gradients with respect to the current sheet for cosmic rays in four rigidity ranges. Gradients vary between approximately -2 and -50% per astronomical unit. The rigidity dependence of the decrease of cosmic ray flux with distance from the current sheet lies between P/sup -0.72/ and P/sup -0.86/, withmore » the exact dependence being determined by the definition used for the median rigidity of each monitor.« less
  • We investigate the two-dimensional, steady state distributions of solar wind speed and 5-GeV cosmic ray flux with respect to the heliospheric current sheet and their variation with the solar cycle from late 1964 through mid-1982. Synoptic K coronameter data are used to locate the current sheet, taken as the center of the ''band of coronal streamers,'' during years of low and intermediate solar activity. We confirm the conclusion that the profile of the solar wind at 1 AU during these years consists of (1) a minimum in mean speed of
  • The relatively abrupt onset of cosmic ray modulation, observed in May 1987 on Earth and in September 1987 by the Pioneer 10 and 11 spacecraft, enables further investigation of the possible effect of the heliospheric current sheet on modulation. According to the gradient drift theory of cosmic ray transport, modulation is associated with solar cycle changes in the current sheet, whose inclination increases systematically from solar minimum to solar maximum. The measured used in testing this hypothesis is the difference in the maximum latitudinal extent of the current sheet in the northern and souther solar hemispheres. This difference is obtainedmore » from contours of the current sheet produced by extrapolating photospheric magnetic field measurements to a solar wind source surface. When the latitude difference, divided by 2 and called the pseudoinclination or pseudotilt angle, is compared with cosmic ray count rates measured on Earth, an excellent correlation is found, as in a previous study of modulation in the years 1976-1986. The abruptness of the onset can be attributed to the greater sensitivity of the cosmic ray intensity to changes in the current sheet when the solar-heliospheric magnetic field is inward in the northern hemisphere as predicted by the model. Thus the observations are found to be consistent with the predictions of the gradient drift model. A preliminary analysis is also carried out to test an alternative, but not necessarily incompatible, hypothesis that large-scale transient solar wind structures (coronal mass ejections, shocks, etc.) form barriers to the inward transport of cosmic rays.« less
  • In this paper we report on a quantitative comparison between theoretical predictions and observations of the intensity of galactic cosmic rays near the interplanetary current sheet. In the present work, comparison of our model calculations is made with a statistical analysis of observations of galactic cosmic rays at the earth and the simultaneous position of the current sheet. Since the observations were made over a period of several years, the inclination of the current sheet varied considerably, and comparison with any one model calculation referring to a given inclination would not be appropriate. In this paper we report the expectedmore » values from our model, using an ensemble of different current sheet inclinations, in order to make the analysis of the computations approximate the method used to analyze the data. We find agreement between theory and observation at energies of the order of a few GeV.« less
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