The primary focus of this paper is on the particle acceleration mechanism in solar coronal three-dimensional reconnection null-point regions .
Starting from a potential field extrapolation of a Solar and Heliospheric Observatory ( SOHO ) magnetogram taken on 2002 November 16 , we first performed magnetohydrodynamics ( MHD ) simulations with horizontal motions observed by SOHO applied to the photospheric boundary of the computational box .
After a build-up of electric current in the fan-plane of the null-point , a sub-section of the evolved MHD data was used as initial and boundary conditions for a kinetic particle-in-cell model of the plasma .
We find that sub-relativistic electron acceleration is mainly driven by a systematic electric field in the current sheet .
A non-thermal population of electrons with a power-law distribution in energy forms in the simulated pre-flare phase , featuring a power-law index of about -1.78 .
This work provides a first step towards bridging the gap between macroscopic scales on the order of hundreds of Mm and kinetic scales on the order of cm in the solar corona , and explains how to achieve such a cross-scale coupling by utilizing either physical modifications or ( equivalent ) modifications of the constants of nature .
With their exceptionally high resolution — up to 135 billion particles and 3.5 billion grid cells of size 17.5 km — these simulations offer a new opportunity to study particle acceleration in solar-like settings .