A Systematic Examination of Particle Motion in a Collapsing Magnetic Trap Model for Solar Flares

Abstract

Context. It has been suggested that collapsing magnetic traps may contribute to accelerating particles to high energies during solar flares. Aims. We present a detailed investigation of the energization processes of particles in collapsing magnetic traps, using a specific model. We also compare for the first time the energization processes in a symmetric and an asymmetric trap model. Methods. Particle orbits are calculated using guiding centre theory. We systematically investigate the dependence of the energization process on initial position, initial energy and initial pitch angle. Results. We find that in our symmetric trap model particles can gain up to about 50 times their initial energy, but that for most initial conditions the energy gain is more moderate. Particles with an initial position in the weak field region of the collapsing trap and with pitch angles around 90 degrees achieve the highest energy gain, with betatron acceleration of the perpendicular energy the dominant energization mechanism. For particles with smaller initial pitch angle, but still outside the loss cone, we find the possibility of a significant increase in parallel energy. This increase in parallel energy can be attributed to the curvature term in the parallel equation of motion and the associated energy gain happens in the center of the trap where the field line curvature has its maximum. We find qualitatively similar results for the asymmetric trap model, but with smaller energy gains and a larger number of particles escaping from the trap.

11 pages, 13 figures. To be published in Astronomy and Astrophysics

References in corpus (3)

• Impulsive phase flare energy transport by large-scale Alfven waves and the electron acceleration problem
• Double Coronal Hard and Soft X-ray Source Observed by RHESSI: Evidence for Magnetic Reconnection and Particle Acceleration in Solar Flares
• An Extension of the Theory of Kinematic MHD Models of Collapsing Magnetic Traps to 2.5D with shear flow and to 3D

Cited by in corpus (5)

• Magnetic Reconnection During the Post-Impulsive Phase of a Long-Duration Solar Flare: Bi-Directional Outflows as a Cause of Microwave and X-ray Bursts
• Spatio-temporal energy partitioning in a non-thermally dominated two-loop solar flare
• Particle energisation in a collapsing magnetic trap model: the relativistic regime
• Onset of Electron Acceleration in a Flare Loop
• Numerical Investigation of Efficient Electron Acceleration at an Unsteady Solar Flare Loop-Top