KINETIC MODELING OF PARTICLE ACCELERATION IN A SOLAR NULL-POINT RECONNECTION REGION

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.

Download Full-text

Fluctuating electric field particle acceleration at a magnetic field null point

10.1063/1.2982457 ◽

2008 ◽

Author(s):

Panagiota Petkaki ◽

Alexander L. MacKinnon ◽

Gang Li ◽

Qiang Hu ◽

Olga Verkhoglyadova ◽

...

Keyword(s):

Magnetic Field ◽

Particle Acceleration ◽

Electric Field ◽

Null Point

Download Full-text

Test particle acceleration in resistive torsional fan magnetic reconnection using laboratory plasma parameters

Journal of Plasma Physics ◽

10.1017/s0022377821001203 ◽

2021 ◽

Vol 87 (6) ◽

Author(s):

D.L. Chesny ◽

N.B. Orange ◽

K.W. Hatfield

Keyword(s):

Particle Acceleration ◽

Magnetic Reconnection ◽

Three Dimensional ◽

Laboratory Plasma ◽

Plasma Parameters ◽

Astrophysical Plasmas ◽

Magnetic Field Topology ◽

Reconnection Region ◽

Fundamental Process ◽

Technology Applications

Particle acceleration via magnetic reconnection is a fundamental process in astrophysical plasmas. Experimental architectures are able to confirm a wide variety of particle dynamics following the two-dimensional Sweet–Parker model, but are limited in their reproduction of the fan-spine magnetic field topology about three-dimensional (3-D) null points. Specifically, there is not yet an experiment featuring driven 3-D torsional magnetic reconnection. To move in this direction, this paper expands on recent work toward the design of an experimental infrastructure for inducing 3-D torsional fan reconnection by predicting feasible particle acceleration profiles. Solutions to the steady-state, kinematic, resistive magnetohydrodynamic equations are used to numerically calculate particle trajectories from a localized resistivity profile using well-understood laboratory plasma parameters. We confine a thin, 10 eV helium sheath following the snowplough model into the region of this localized resistivity and find that it is accelerated to energies of ${\approx }2$ keV. This sheath is rapidly accelerated and focused along the spine axis propagating a few centimetres from the reconnection region. These dynamics suggest a novel architecture that may hold promise for future experiments studying solar coronal particle acceleration and for technology applications such as spacecraft propulsion.

Download Full-text

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

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307009994 ◽

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.

Download Full-text

Particle Acceleration by Dense Impulsive Structures Moving in Ambient Magnetospheric Plasma. 3‐D Hybrid Kinetic Modeling and MMS Observations

Geophysical Research Letters ◽

10.1029/2020gl088590 ◽

2021 ◽

Vol 48 (3) ◽

Author(s):

A. S. Lipatov ◽

L. A. Avanov ◽

B. L. Giles

Keyword(s):

Particle Acceleration ◽

Kinetic Modeling ◽

Magnetospheric Plasma

Download Full-text

Particle acceleration by fluctuating electric fields at a magnetic field null point

Astronomy and Astrophysics ◽

10.1051/0004-6361:20066961 ◽

2007 ◽

Vol 472 (2) ◽

pp. 623-632 ◽

Cited By ~ 19

Author(s):

P. Petkaki ◽

A. L. MacKinnon

Keyword(s):

Magnetic Field ◽

Particle Acceleration ◽

Electric Fields ◽

Null Point

Download Full-text

Solar Coronal Loop Dynamics Near the Null Point Above Active Region NOAA 2666

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2018.20 ◽

2018 ◽

Vol 35 ◽

Author(s):

B. Filippov

Keyword(s):

Magnetic Field ◽

Vertical Direction ◽

Coronal Magnetic Field ◽

Null Point ◽

Coronal Loops ◽

Active Region Noaa ◽

Reconnection Region ◽

Loop Dynamics ◽

Field Lines ◽

Western Limb

AbstractWe analyse observations of a saddle-like structure in the corona above the western limb of the Sun on 2017 July 18. The structure was clearly outlined by coronal loops with typical coronal temperature no more than 1 MK. The dynamics of loops showed convergence towards the centre of the saddle in the vertical direction and divergence in the horizontal direction. The event is a clear example of smooth coronal magnetic field reconnection. No heating manifestations in the reconnection region or magnetically connected areas were observed. Potential magnetic field calculations, which use as the boundary condition the SDO/HMI magnetogram taken on July 14, showed the presence of a null point at the height of 122 arcsec above the photosphere just at the centre of the saddle structure. The shape of field lines fits the fan-spine magnetic configuration above NOAA 2666.

Download Full-text