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Author name code: frogner
ADS astronomy entries on 2022-09-14
author:Frogner, Lars

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Title: Accelerated particle beams in a 3D simulation of the quiet Sun
Authors: Frogner, L.; Gudiksen, B. V.; Bakke, H.
2020A&A...643A..27F    Altcode: 2020arXiv200514483F
  Context. Observational and theoretical evidence suggest that beams
  of accelerated particles are produced in flaring events of all sizes
  in the solar atmosphere, from X-class flares to nanoflares. Current
  models of these types of particles in flaring loops assume an
  isolated 1D atmosphere. <BR /> Aims: A more realistic environment
  for modelling accelerated particles can be provided by 3D radiative
  magnetohydrodynamics codes. Here, we present a simple model for particle
  acceleration and propagation in the context of a 3D simulation of
  the quiet solar atmosphere, spanning from the convection zone to the
  corona. We then examine the additional transport of energy introduced
  by the particle beams. <BR /> Methods: The locations of particle
  acceleration associated with magnetic reconnection were identified by
  detecting changes in magnetic topology. At each location, the parameters
  of the accelerated particle distribution were estimated from local
  conditions. The particle distributions were then propagated along the
  magnetic field, and the energy deposition due to Coulomb collisions
  with the ambient plasma was computed. <BR /> Results: We find that
  particle beams originate in extended acceleration regions that are
  distributed across the corona. Upon reaching the transition region,
  they converge and produce strands of intense heating that penetrate the
  chromosphere. Within these strands, beam heating consistently dominates
  conductive heating below the bottom of the transition region. This
  indicates that particle beams qualitatively alter the energy transport
  even outside of active regions.

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Title: Non-thermal electrons from solar nanoflares
Authors: Bakke, Helle; Frogner, Lars; Gudiksen, Boris Vilhelm
2018arXiv181112404B    Altcode:
  Context. We introduce a model for including accelerated particles
  in pure magnetohydrodynamics (MHD) simulations of the solar
  atmosphere. Aims. We show that the method is viable and produces
  results that enhance the realism of MHD simulations of the solar
  atmosphere. Methods. The acceleration of high-energy electrons in
  solar flares is an accepted fact, but is not included in the most
  advanced 3D simulations of the solar atmosphere. The effect of the
  acceleration is not known, and here we introduce a simple method to
  account for the ability of the accelerated electrons to move energy
  from the reconnection sites and into the dense transition zone and
  chromosphere. Results. The method was only run for a short time and with
  low reconnection energies, but this showed that the reconnection process
  itself changes, and that there is a clear effect on the observables
  at the impact sites of the accelerated electrons. Further work will
  investigate the effect on the reconnection sites and the impact sites
  in detail.

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Title: Non-thermal electrons from solar nanoflares. In a 3D radiative
    MHD simulation
Authors: Bakke, H.; Frogner, L.; Gudiksen, B. V.
2018A&A...620L...5B    Altcode:
  Context. We introduce a model for including accelerated particles in
  pure magnetohydrodynamics (MHD) simulations of the solar atmosphere. <BR
  /> Aims: We show that the method is viable and produces results that
  enhance the realism of MHD simulations of the solar atmosphere. <BR />
  Methods: The acceleration of high-energy electrons in solar flares is an
  accepted fact, but is not included in the most advanced 3D simulations
  of the solar atmosphere. The effect of the acceleration is not known,
  and here we introduce a simple method to account for the ability of
  the accelerated electrons to move energy from the reconnection sites
  and into the dense transition zone and chromosphere. <BR /> Results:
  The method was only run for a short time and with low reconnection
  energies, but this showed that the reconnection process itself changes,
  and that there is a clear effect on the observables at the impact sites
  of the accelerated electrons. Further work will investigate the effect
  on the reconnection sites and the impact sites in detail.