scholarly journals Particle acceleration in three-dimensional reconnection regions: A new test particle approach

1999 ◽  
Vol 6 (11) ◽  
pp. 4318-4327 ◽  
Author(s):  
Rüdiger Schopper ◽  
Guido T. Birk ◽  
Harald Lesch
Keyword(s):  
Particle Acceleration ◽  
Test Particle ◽  
Three Dimensional ◽  
Particle Approach

scholarly journals Test Particle Acceleration in Three-dimensional Magnetohydrodynamic Turbulence

2003 ◽  
Vol 597 (1) ◽  
pp. L81-L84 ◽  
Author(s):  
P. Dmitruk ◽  
W. H. Matthaeus ◽  
N. Seenu ◽  
M. R. Brown
Keyword(s):  
Particle Acceleration ◽  
Test Particle ◽  
Three Dimensional ◽  
Magnetohydrodynamic Turbulence

scholarly journals TEST-PARTICLE ACCELERATION IN A HIERARCHICAL THREE-DIMENSIONAL TURBULENCE MODEL

2014 ◽  
Vol 783 (2) ◽  
pp. 143 ◽  
Author(s):  
S. Dalena ◽  
A. F. Rappazzo ◽  
P. Dmitruk ◽  
A. Greco ◽  
W. H. Matthaeus
Keyword(s):  
Particle Acceleration ◽  
Turbulence Model ◽  
Test Particle ◽  
Three Dimensional

scholarly journals Particle acceleration in coalescent and squashed magnetic islands

2020 ◽  
Vol 635 ◽  
pp. A116 ◽  
Author(s):  
Q. Xia ◽  
V. Zharkova
Keyword(s):  
Particle Acceleration ◽  
Current Sheet ◽  
Test Particle ◽  
Pitch Angle ◽  
Magnetic Islands ◽  
Current Sheets ◽  
Aspect Ratios ◽  
Energy Gains ◽  
Particle Approach ◽  
Accelerated Particles

Aims. Particles are known to have efficient acceleration in reconnecting current sheets with multiple magnetic islands that are formed during a reconnection process. Using the test-particle approach, the recent investigation of particle dynamics in 3D magnetic islands, or current sheets with multiple X- and O-null points revealed that the particle energy gains are higher in squashed magnetic islands than in coalescent ones. However, this approach did not factor in the ambient plasma feedback to the presence of accelerated particles, which affects their distributions within the acceleration region. Methods. In the current paper, we use the particle-in-cell (PIC) approach to investigate further particle acceleration in 3D Harris-type reconnecting current sheets with coalescent (merging) and squashed (contracting) magnetic islands with different magnetic field topologies, ambient densities ranging between 108 − 1012 m−3, proton-to-electron mass ratios, and island aspect ratios. Results. In current sheets with single or multiple X-nullpoints, accelerated particles of opposite charges are separated and ejected into the opposite semiplanes from the current sheet midplane, generating a strong polarisation electric field across a current sheet. Particles of the same charge form two populations: transit and bounced particles, each with very different energy and asymmetric pitch-angle distributions, which can be distinguished from observations. In some cases, the difference in energy gains by transit and bounced particles leads to turbulence generated by Buneman instability. In magnetic island topology, the different reconnection electric fields in squashed and coalescent islands impose different particle drift motions. This makes particle acceleration more efficient in squashed magnetic islands than in coalescent ones. The spectral indices of electron energy spectra are ∼ − 4.2 for coalescent and ∼ − 4.0 for squashed islands, which are lower than reported from the test-particle approach. The particles accelerated in magnetic islands are found trapped in the midplane of squashed islands, and shifted as clouds towards the X-nullpoints in coalescent ones. Conclusions. In reconnecting current sheets with multiple X- and O-nullpoints, particles are found accelerated on a much shorter spatial scale and gaining higher energies than near a single X-nullpoint. The distinct density and pitch-angle distributions of particles with high and low energy detected with the PIC approach can help to distinguish the observational features of accelerated particles.

The effect of magnetic topology on particle acceleration in a three-dimensional reconnecting current sheet: a test-particle approach

2009 ◽  
Vol 75 (2) ◽  
pp. 159-181 ◽  
Author(s):  
V. V. ZHARKOVA ◽  
O. V. AGAPITOV
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electric Field ◽  
Current Sheet ◽  
Test Particle ◽  
Three Dimensional ◽  
Energy Spectra ◽  
Particle In Cell ◽  
Particle Approach ◽  
Reconnecting Current Sheet

AbstractElectron and proton acceleration by a drifted super-Dreicer electric field is investigated in a strongly compressed non-neutral reconnecting current sheet (NRCS). The guiding field is assumed to be constant within a reconnecting current sheet (RCS) and parallel to the direction of the drifted electric field. The other two magnetic field components, transverse and tangential, are considered to vary exponentially and linearly with distances from the X-nullpoint. The proton and electron energy spectra are calculated numerically in a model RCS with different magnetic field topologies by solving an equation of motion in the test-particle approach with some test with a particle-in-cell (PIC) approach. Three kinds electric field generated inside a RCS are considered: a drifted electric field caused by the plasma inflows formed during a magnetic reconnection process; a polarization electric field induced by the accelerated protons and electrons; and a turbulent electric field induced by instabilities generated by accelerated particles. Electron and proton densities, and energy spectra inside a RCS and at ejection are found to be strongly affected by the magnetic field topology: for stronger magnetic fields the spectra are softer having a small higher-energy cutoff while for weaker magnetic fields the spectra are harder with much larger upper cutoff energies. Depending on the magnetic component ratios and drifted electric field magnitude, particles are found to be ejected either as quasi-thermal flows with very high temperatures or as focused power-law beams. A polarization field is found to reduce the acceleration time inside a RCS and to increase the energy gained by particles at acceleration by a pure drifted electric field by a few orders of magnitude. The turbulent electric field induced by the two beam instabilities of the same kind of particles leads to a significant increase in the number of particles with higher energies resulting in a flattening of their energy spectra.

scholarly journals Particle Orbits, Trapping, and Acceleration in a Filamentary Current Sheet Model

1994 ◽  
Vol 142 ◽  
pp. 719-728
Author(s):  
Bernhard Kliem
Keyword(s):  
Particle Acceleration ◽  
Electric Field ◽  
Test Particle ◽  
Solar Flares ◽  
Acceleration Of Particles ◽  
Acceleration Process ◽  
Two Dimensional ◽  
Magnetic Island ◽  
Particle Orbits ◽  
Island Dynamics

AbstractTest particle orbits in the two-dimensional Fadeev equilibrium with a perpendicular electric field added are analyzed to show that impulsive bursty reconnection, which has been proposed as a model for fragmentary energy release in solar flares, may account also for particle acceleration to (near) relativistic energies within a fraction of a second. The convective electric field connected with magnetic island dynamics can play an important role in the acceleration process.Subject headings: acceleration of particles — MHD — plasmas — Sun: corona — Sun: flares

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