scholarly journals Jets of energetic particles generated by magnetic reconnection at a three-dimensional magnetic null

2006 ◽  
Vol 2 (14) ◽  
pp. 98-98
Author(s):  
Silvia Dalla ◽  
Philippa K. Browning
Keyword(s):  
Particle Acceleration ◽  
Magnetic Reconnection ◽  
Energetic Particle ◽  
Three Dimensional ◽  
Null Point ◽  
Numerical Code ◽  
Coronal Magnetic Fields ◽  
Field Lines ◽  
Magnetic Null ◽  
Magnetic Null Point

AbstractMagnetic reconnection is a candidate mechanism for particle acceleration in a variety of astrophysical contexts. It is now widely accepted that reconnection plays a key role in solar flares, and reconstructions of coronal magnetic fields indicate that three-dimensional (3D) magnetic null points can be present during flares. We investigate particle acceleration during spine reconnection at a 3D magnetic null point, using a test particle numerical code. We observe efficient particle acceleration and find that two energetic populations are produced: a trapped population of particles that remain in the vicinity of the null, and an escaping population, which leave the configuration in two symmetric jets along field lines near the spine. While the parameters used in our simulation aim to represent solar coronal plasma conditions of relevance for acceleration in flares, the fact that the 3D spine reconnection configuration naturally results in energetic particle jets may be of importance in other astrophysical situations. We also compare the results obtained for the spine reconnection regime with those for the other possible mode of 3D reconnection, fan reconnection. We find that in the latter case energetic particle jets are not produced, though acceleration is observed.

scholarly journals Spatially Separated Electron and Proton Beams in a Simulated Solar Coronal Jet

2021 ◽  
Vol 923 (2) ◽  
pp. 163
Author(s):  
Ross Pallister ◽  
Peter F. Wyper ◽  
David I. Pontin ◽  
C. Richard DeVore ◽  
Federica Chiti
Keyword(s):  
Particle Acceleration ◽  
Particle Deposition ◽  
Lower Boundary ◽  
Impulsive Phase ◽  
Null Point ◽  
Solar Photosphere ◽  
In Situ Observations ◽  
Magnetic Null ◽  
Magnetic Null Point

Abstract Magnetic reconnection is widely accepted to be a major contributor to nonthermal particle acceleration in the solar atmosphere. In this paper we investigate particle acceleration during the impulsive phase of a coronal jet, which involves bursty reconnection at a magnetic null point. A test-particle approach is employed, using electromagnetic fields from a magnetohydrodynamic simulation of such a jet. Protons and electrons are found to be accelerated nonthermally both downwards toward the domain’s lower boundary and the solar photosphere, and outwards along the axis of the coronal jet and into the heliosphere. A key finding is that a circular ribbon of particle deposition on the photosphere is predicted, with the protons and electrons concentrated in different parts of the ribbon. Furthermore, the outgoing protons and electrons form two spatially separated beams parallel to the axis of the jet, signatures that may be observable in in-situ observations of the heliosphere.

Proton acceleration in three-dimensional non-null magnetic reconnection

2016 ◽  
Vol 82 (5) ◽  
Author(s):  
Z. Akbari ◽  
M. Hosseinpour ◽  
M. A. Mohammadi
Keyword(s):  
Magnetic Field ◽  
Energy Distribution ◽  
Magnetic Reconnection ◽  
Electric Fields ◽  
Three Dimensional ◽  
Null Point ◽  
Proton Acceleration ◽  
Electric And Magnetic Fields ◽  
Field Lines ◽  
The Magnetic Field

In a three-dimensional non-null magnetic reconnection, the process of magnetic reconnection takes place in the absence of a null point where the magnetic field vanishes. By randomly injecting a population of 10 000 protons, the trajectory and energy distribution of accelerated protons are investigated in the presence of magnetic and electric fields of a particular model of non-null magnetic reconnection with the typical parameters for the solar corona. The results show that protons are accelerated along the magnetic field lines away from the non-null point only at azimuthal angles where the magnitude of the electric field is strongest and therefore particles obtain kinetic energies of the order of thousands of MeV and even higher. Moreover, the energy distribution of the population depends strongly on the amplitude of the electric and magnetic fields. Comparison shows that a non-null magnetic reconnection is more efficient in accelerating protons to very high GeV energies than a null-point reconnection.

scholarly journals A Fundamental Mechanism of Solar Eruption Initiation

2021 ◽  
Author(s):  
Chaowei Jiang ◽  
Xueshang Feng ◽  
Rui Liu ◽  
Xiaoli Yan ◽  
Qiang Hu ◽  
...  
Keyword(s):  
Source Region ◽  
Three Dimensional ◽  
Flux Rope ◽  
Null Point ◽  
Magnetic Flux Rope ◽  
Solar Eruptions ◽  
Magnetohydrodynamic Simulations ◽  
Magnetic Null ◽  
Shearing Motion ◽  
Magnetic Null Point

<p>Solar eruptions are spectacular magnetic explosions in the Sun's corona and how they are initiated remains unclear. Prevailing theories often rely on special magnetic topologies, such as magnetic flux rope and magnetic null point, which, however, may not generally exist in the pre-eruption source region of corona. Here using fully three-dimensional magnetohydrodynamic simulations with high accuracy, we show that solar eruption can be initiated in a single bipolar configuration with no additional special topology. Through photospheric shearing motion alone, an electric current sheet forms in the highly sheared core field of the magnetic arcade during its quasi-static evolution. Once magnetic reconnection sets in, the whole arcade is expelled impulsively, forming a fast-expanding twisted flux rope with a highly turbulent reconnecting region underneath. The simplicity and efficacy of this scenario argue strongly for its fundamental importance in the initiation of solar eruptions.</p>

Toward laboratory torsional spine magnetic reconnection

2017 ◽  
Vol 83 (6) ◽  
Author(s):  
David L. Chesny ◽  
N. Brice Orange ◽  
Hakeem M. Oluseyi ◽  
David R. Valletta
Keyword(s):  
Magnetic Reconnection ◽  
Kinetic Parameters ◽  
Three Dimensional ◽  
Limited Range ◽  
Null Point ◽  
Plasma Parameters ◽  
Astrophysical Plasmas ◽  
Current Sheets ◽  
Practical Applications ◽  
Field Lines

Magnetic reconnection is a fundamental energy conversion mechanism in nature. Major attempts to study this process in controlled settings on Earth have largely been limited to reproducing approximately two-dimensional (2-D) reconnection dynamics. Other experiments describing reconnection near three-dimensional null points are non-driven, and do not induce any of the 3-D modes of spine fan, torsional fan or torsional spine reconnection. In order to study these important 3-D modes observed in astrophysical plasmas (e.g. the solar atmosphere), laboratory set-ups must be designed to induce driven reconnection about an isolated magnetic null point. As such, we consider the limited range of fundamental resistive magnetohydrodynamic (MHD) and kinetic parameters of dynamic laboratory plasmas that are necessary to induce the torsional spine reconnection (TSR) mode characterized by a driven rotational slippage of field lines – a feature that has yet to be achieved in operational laboratory magnetic reconnection experiments. Leveraging existing reconnection models, we show that within a${\lesssim}1~\text{m}^{3}$apparatus, TSR can be achieved in dense plasma regimes (${\sim}10^{24}~\text{m}^{-3}$) in magnetic fields of${\sim}10^{-1}~\text{T}$. We find that MHD and kinetic parameters predict reconnection in thin${\lesssim}20~\unicode[STIX]{x03BC}\text{m}$current sheets on time scales of${\lesssim}10~\text{ns}$. While these plasma regimes may not explicitly replicate the plasma parameters of observed astrophysical phenomena, studying the dynamics of the TSR mode within achievable set-ups signifies an important step in understanding the fundamentals of driven 3-D magnetic reconnection and the self-organization of current sheets. Explicit control of this reconnection mode may have implications for understanding particle acceleration in astrophysical environments, and may even have practical applications to fields such as spacecraft propulsion.

Dynamic non-null magnetic reconnection in three dimensions. I. Particular solutions

2006 ◽  
Vol 462 (2074) ◽  
pp. 2877-2895 ◽  
Author(s):  
Antonia Wilmot-Smith ◽  
Gunnar Hornig ◽  
Eric Priest
Keyword(s):  
Magnetic Reconnection ◽  
Kinematic Model ◽  
Three Dimensional ◽  
Momentum Equation ◽  
Null Point ◽  
Three Dimensions ◽  
Diffusion Region ◽  
Ideal Solution ◽  
Ideal Solutions ◽  
Field Lines

A stationary model of three-dimensional magnetic reconnection in the absence of a null point is presented, with a non-ideal region that is localized in space. Analytical solutions to the resistive magnetohydrodynamic equations are obtained, with the momentum equation included so that the model is fully dynamic, and thus extends the previous kinematic solutions. A splitting of variables allows solutions to be written in terms of a particular non-ideal solution, on which ideal solutions may be superposed. For the non-ideal solution alone, it is shown that only the field lines linking the diffusion region are affected by the reconnection process, and counter-rotating flows above and below the diffusion region are present. It is only the dimensions of the diffusion region along the reconnection line that are important for the reconnection rate. Many features of the previous stationary kinematic model are also observed here.

Instability of isolated three-dimensional magnetic null points

1998 ◽  
Vol 59 (3) ◽  
pp. 537-541 ◽  
Author(s):  
MANUEL NÚÑEZ
Keyword(s):  
Linear Stability ◽  
Three Dimensional ◽  
Null Point ◽  
Static Equilibrium ◽  
Flux Surface ◽  
Form Part ◽  
Magnetic Null ◽  
Transverse Oscillations

Although most magnetic neutral points occurring in nature seem to form part of a continuum, recent studies of reconnection have centred on static equilibria in the neighbourhood of an isolated three-dimensional null point. The linear stability of this configuration is studied here. It is found that one may choose a flux surface so that transverse oscillations localized around the surface and polarized within it must grow exponentially in time. This means that any static equilibrium containing an isolated three-dimensional null point is linearly unstable.

Cluster Observation of Electrostatic Solitary Waves around Magnetic Null Point in Thin Current Sheet

2010 ◽  
Vol 27 (1) ◽  
pp. 019401 ◽  
Author(s):  
Li Shi-You ◽  
Deng Xiao-Hua ◽  
Zhou Meng ◽  
Yuan Zhi-Gang ◽  
Wang Jing-Fang ◽  
...  
Keyword(s):  
Current Sheet ◽  
Solitary Waves ◽  
Null Point ◽  
Thin Current Sheet ◽  
Magnetic Null ◽  
Magnetic Null Point
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