scholarly journals Particle acceleration in solar flares: linking magnetic energy release with the acceleration process

2007 ◽  
Vol 471 (3) ◽  
pp. 993-997 ◽  
Author(s):  
C. Dauphin
1995 ◽  
Vol 451 ◽  
pp. 843 ◽  
Author(s):  
Y. Q. Hu ◽  
X. Li ◽  
G. X. Ai

2021 ◽  
Vol 919 (2) ◽  
pp. 111
Author(s):  
Fan Guo ◽  
Xiaocan Li ◽  
William Daughton ◽  
Hui Li ◽  
Patrick Kilian ◽  
...  

2001 ◽  
Vol 550 (1) ◽  
pp. L105-L108 ◽  
Author(s):  
A. G. Kosovichev ◽  
V. V. Zharkova

1994 ◽  
Vol 142 ◽  
pp. 719-728
Author(s):  
Bernhard Kliem

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


2000 ◽  
Vol 195 ◽  
pp. 15-25
Author(s):  
R. P. Lin

The Sun accelerates ions up to tens of GeV and electrons up to 100s of MeV in solar flares and coronal mass ejections. The energy in the accelerated tens-of-keV electrons and possibly ~1 MeV ions constitutes a significant fraction of the total energy released in a flare, implying that the particle acceleration and flare energy release mechanisms are intimately related. The total rate of energy release in transients from flares down to microflares/nanoflares may be significant for heating the active solar corona.Shock waves driven by fast CMEs appear to accelerate the high-energy particles in large solar energetic particle events detected at 1 AU. Smaller SEP events are dominated by ~1 to tens-of-keV electrons, with low fluxes of up to a few MeV/nucleon ions, typically enriched in 3He. The acceleration in gamma-ray flares appears to resemble that in these small electron-3He SEP events.


1990 ◽  
Vol 142 ◽  
pp. 438-438
Author(s):  
B. Lokanadham

A study of the simultaneous observations of solar flares in optical, radio and X-ray bands is important in understanding the process of energy release and particle acceleration in the explosive phenomena of solar flares. In order to determine the characteristics of such energetic electrons in solar flares, a total number of 50 two-ribbon flares have been carefully selected during the period 1979-89 having simultaneous observational data in the optical, X-ray and radio bands.


2005 ◽  
Vol 13 ◽  
pp. 128-131
Author(s):  
Mark G. Linton

AbstractHelicity in coronal magnetic fields, often occurring in the form of twisted or sheared fields, can provide surplus energy which is available for release in solar flares. In this paper, several models of how this extra, non-potential, energy can be released will be reviewed. For example, twisted flux tubes can release excess energy via the kink instability. Or energy can be released via a transfer of helicity between different magnetic tubes. For untwisted field, the mutual helicity between flux tubes provides a measure of the shear in the fields, and therefore how much energy is available for release in a flare. For twisted flux tubes, the twist helicity of each tube in combination with the mutual helicity between the tubes dictate what type of reconnection the tubes can undergo and how much energy is available for release. Measuring the helicity of coronal active regions, and studying how this helicity affects magnetic energy release is therefore vital for our understanding of and our ability to predict solar flares.


2020 ◽  
Author(s):  
Xiaocan Li ◽  
Fan Guo

<p>Magnetic reconnection is a primary driver of magnetic energy release and particle acceleration processes in space and astrophysical plasmas. Solar flares are a great example where observations have suggested that a large fraction of magnetic energy is converted into nonthermal particles and radiation. One of the major unsolved problems in reconnection studies is nonthermal particle acceleration. In the past decade or two, 2D kinetic simulations have been widely used and have identified several acceleration mechanisms in reconnection. Recent 3D simulations have shown that the reconnection layer naturally generates magnetic turbulence. Here we report our recent progresses in building a macroscopic model that includes these physics for explaining particle acceleration during solar flares. We show that, for sufficient large systems, high-energy particle acceleration processes can be well described as flow compression and shear. By means of 3D kinetic simulations, we found that the self-generated turbulence is essential for the formation of power-law electron energy spectrum in non-relativistic reconnection. Based on these results, we then proceed to solve an energetic particle transport equation in a compressible reconnection layer provided by high-Lundquist-number MHD simulations. Due to the compression effect, particles are accelerated to high energies and develop power-law energy distributions. The power-law index and maximum energy are both comparable to solar flare observations. This study clarifies the nature of particle acceleration in large-scale reconnection sites and initializes a framework for studying large-scale particle acceleration during solar flares.</p>


Sign in / Sign up

Export Citation Format

Share Document