Dynamics of charged particle motion in the vicinity of three dimensional magnetic null points: Energization and chaos
Abstract
Using a full orbit test particle approach, we analyse the motion of a single proton in the vicinity of magnetic null point configurations which are solutions to the kinematic, steady state, resistive magnetohydrodynamics equations. We consider two magnetic configurations, namely, the sheared and torsional spine reconnection regimes [E. R. Priest and D. I. Pontin, Phys. Plasmas 16, 122101 (2009); P. Wyper and R. Jain, Phys. Plasmas 17, 092902 (2010)]; each produce an associated electric field and thus the possibility of accelerating charged particles to high energy levels, i.e., > MeV, as observed in solar flares [R. P. Lin, Space Sci. Rev. 124, 233 (2006)]. The particle's energy gain is strongly dependent on the location of injection and is characterised by the angle of approach β, with optimum angle of approach β{sub opt} as the value of β which produces the maximum energy gain. We examine the topological features of each regime and analyse the effect on the energy gain of the proton. We also calculate the complete Lyapunov spectrum for the considered dynamical systems in order to correctly quantify the chaotic nature of the particle orbits. We find that the sheared model is a good candidate for the acceleration of particles, andmore »
 Authors:
 School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)
 Publication Date:
 OSTI Identifier:
 22408229
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 3; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ACCELERATION; CHAOS THEORY; CHARGED PARTICLES; ELECTRIC FIELDS; ENERGY LEVELS; LYAPUNOV METHOD; MAGNETIC FIELD CONFIGURATIONS; MAGNETOHYDRODYNAMICS; MATHEMATICAL SOLUTIONS; MEV RANGE; ORBITS; PROTONS; SHEAR; SOLAR FLARES; SPECTRA; STEADYSTATE CONDITIONS; TEST PARTICLES; THREEDIMENSIONAL CALCULATIONS; TOPOLOGY
Citation Formats
Gascoyne, Andrew, Email: a.d.gascoyne@sheffield.ac.uk. Dynamics of charged particle motion in the vicinity of three dimensional magnetic null points: Energization and chaos. United States: N. p., 2015.
Web. doi:10.1063/1.4916402.
Gascoyne, Andrew, Email: a.d.gascoyne@sheffield.ac.uk. Dynamics of charged particle motion in the vicinity of three dimensional magnetic null points: Energization and chaos. United States. doi:10.1063/1.4916402.
Gascoyne, Andrew, Email: a.d.gascoyne@sheffield.ac.uk. 2015.
"Dynamics of charged particle motion in the vicinity of three dimensional magnetic null points: Energization and chaos". United States.
doi:10.1063/1.4916402.
@article{osti_22408229,
title = {Dynamics of charged particle motion in the vicinity of three dimensional magnetic null points: Energization and chaos},
author = {Gascoyne, Andrew, Email: a.d.gascoyne@sheffield.ac.uk},
abstractNote = {Using a full orbit test particle approach, we analyse the motion of a single proton in the vicinity of magnetic null point configurations which are solutions to the kinematic, steady state, resistive magnetohydrodynamics equations. We consider two magnetic configurations, namely, the sheared and torsional spine reconnection regimes [E. R. Priest and D. I. Pontin, Phys. Plasmas 16, 122101 (2009); P. Wyper and R. Jain, Phys. Plasmas 17, 092902 (2010)]; each produce an associated electric field and thus the possibility of accelerating charged particles to high energy levels, i.e., > MeV, as observed in solar flares [R. P. Lin, Space Sci. Rev. 124, 233 (2006)]. The particle's energy gain is strongly dependent on the location of injection and is characterised by the angle of approach β, with optimum angle of approach β{sub opt} as the value of β which produces the maximum energy gain. We examine the topological features of each regime and analyse the effect on the energy gain of the proton. We also calculate the complete Lyapunov spectrum for the considered dynamical systems in order to correctly quantify the chaotic nature of the particle orbits. We find that the sheared model is a good candidate for the acceleration of particles, and for increased shear, we expect a larger population to be accelerated to higher energy levels. In the strong electric field regime (E{sub 0}=1500 V/m), the torsional model produces chaotic particle orbits quantified by the calculation of multiple positive Lyapunov exponents in the spectrum, whereas the sheared model produces chaotic orbits only in the neighbourhood of the null point.},
doi = {10.1063/1.4916402},
journal = {Physics of Plasmas},
number = 3,
volume = 22,
place = {United States},
year = 2015,
month = 3
}

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Torsional magnetic reconnection at three dimensional null points: A phenomenological study
Magnetic reconnection around three dimensional (3D) magnetic null points is the natural progression from Xpoint reconnection in two dimensions. In 3D the separator field lines of the Xpoint are replaced with the spine line and fan plane (the field lines which asymptotically approach or recede from the null). In this work analytical models are developed for the newly classified torsional spine and torsional fan reconnection regimes by solving the steady state, kinematic, resistive magnetohydrodynamic equations. Reconnection is localized to around the null through the use of a localized field perturbation leading to a localized current while a constant resistivity ismore »