scholarly journals Magnetic island merging: Two-dimensional MHD simulation and test-particle modeling

2021 ◽  
Vol 28 (9) ◽  
pp. 092113
Author(s):  
Xiaozhou Zhao ◽  
Fabio Bacchini ◽  
Rony Keppens
Keyword(s):  
Test Particle ◽  
Two Dimensional ◽  
Magnetic Island ◽  
Mhd Simulation ◽  
Particle Modeling

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

Effect of plasma-β on the onset of plasmoid instability in Sweet–Parker current sheets

2014 ◽  
Vol 80 (5) ◽  
pp. 655-665 ◽  
Author(s):  
H. Baty
Keyword(s):  
Magnetic Reconnection ◽  
Temperature Increase ◽  
Numerical Study ◽  
Two Dimensional ◽  
Magnetic Island ◽  
Current Sheets ◽  
A Value ◽  
Similar Dependence ◽  
Definition Of ◽  
Local Temperature Increase

AbstractA numerical study of magnetic reconnection in two-dimensional resistive magnetohydrodynamics for Sweet–Parker current sheets that are subject to plasmoid instability is carried out. The effect of the initial upstream plasma-β on the critical Lundquist number Sc for the onset of plasmoid instability is studied. Our results indicate a weak dependence, with a value of Sc ≃ 1.5 × 104 in the limit of zero β, and a value of Sc ≃ 1 × 104 in the opposite high β regime (β ≫ 1). A similar dependence was previously obtained (Ni et al. 2012 Phys. Plasm. 19, 072902), but with a somewhat much larger variation, that can be largely attributed to the different configuration setup used in their study, and also to the definition of the Lundquist number. This conclusion does not depend significantly on the equilibrium used, i.e. both initial configurations with either plasma density or temperature spatial variations lead to very similar results. Finally, we show that the inner plasmoid structure appears as an under-dense hotted magnetic island, with a local temperature increase that is noticeably strengthened for low β cases.

scholarly journals A deep insight into the ion foreshock with the help of test particle two-dimensional simulations

2020 ◽  
Vol 38 (6) ◽  
pp. 1217-1235
Author(s):  
Philippe Savoini ◽  
Bertrand Lembège
Keyword(s):  
Electric Field ◽  
Shock Front ◽  
Test Particle ◽  
Field Component ◽  
Upstream Region ◽  
Mirror Reflection ◽  
Two Dimensional ◽  
Shock Profiles ◽  
The Impact

Abstract. Two-dimensional (2D) test particle simulations based on shock profiles issued from 2D full particle-in-cell (PIC) simulations are used in order to analyze the formation processes of ions back streaming within the upstream region after interacting with a quasi-perpendicular curved shock front. Two different types of simulations have been performed based on (i) a fully consistent expansion (FCE) model, which includes all self-consistent shock profiles at different times, and (ii) a homothetic expansion (HE) model in which shock profiles are fixed at certain times and artificially expanded in space. The comparison of both configurations allows one to analyze the impact of the front nonstationarity on the back-streaming population. Moreover, the role of the space charge electric field El is analyzed by either including or canceling the El component in the simulations. A detailed comparison of these last two different configurations allows one to show that this El component plays a key role in the ion reflection process within the whole quasi-perpendicular propagation range. Simulations provide evidence that the different field-aligned beam (FAB) and gyro-phase bunched (GPB) populations observed in situ are essentially formed by a Et×B drift in the velocity space involving the convective electric field Et. Simultaneously, the study emphasizes (i) the essential action of the magnetic field component on the GPB population (i.e., mirror reflection) and (ii) the leading role of the convective field Et in the FAB energy gain. In addition, the electrostatic field component El is essential for reflecting ions at high θBn angles and, in particular, at the edge of the ion foreshock around 70∘. Moreover, the HE model shows that the rate BI% of back-streaming ions is strongly dependent on the shock front profile, which varies because of the shock front nonstationarity. In particular, reflected ions appear to escape periodically from the shock front as bursts with an occurrence time period associated to the self-reformation of the shock front.

Interaction of test particles with a plasma

1971 ◽  
Vol 5 (3) ◽  
pp. 441-454 ◽  
Author(s):  
E. W. Laingal ◽  
A. Lamont ◽  
P. J. Fielding
Keyword(s):  
Computer Simulation ◽  
Test Particle ◽  
Plasma Oscillation ◽  
Two Dimensional ◽  
Thermal Velocity ◽  
Debye Shielding ◽  
Maxwellian Plasma ◽  
Test Particles ◽  
Stationary Test ◽  
Concentration Of Electrons

The effect of a test particle, moving through a two-dimensional Maxwellian plasma, has been studied both analytically and by computer simulation. For a stationary test particle, Debye shielding occurs. When the velocity of the test particle approaches the electron thermal velocity, there is a concentration of electrons several Debye lengths downstream, an effect which is essentially a heavily damped plasma oscillation. The analytic results agree closely with the computer simulation. As the velocity of the test particle increases, it is shown analytically that the damping diminishes, and eventually a fully developed plasma oscillation is established in the wake of the particle.

Sign in / Sign up

Export Citation Format

Share Document