The sun is the most energetic particle accelerator in the solar system, producing ions of up to GeV and electrons of up to tens of MeV. Large solar flares are the most powerful explosions in the solar system, releasing up to 10^32-10^33 ergs in ~10^2-10^3s. The accelerated 20-100keV electrons and the sometimes greater than ~1MeV ions appear to contain ~10%-50% of this energy, indicating that the particle acceleration and energy release processes are intimately linked. Flare-accelerated electrons and ions colliding with the ambient solar atmosphere produce bremsstrahlung hard X-ray and gamma-ray line emission. Hard X-rays can provides us with the most important information required for understanding the energy release process and the mechanism or mechanisms by which particles are energized during flare. So, one of the most fascinating aspects of solar flares is how the particles are accelerating to high energies. This thesis is structured as follow: In chapter one, on the basis of surveying a number of references, we summarized the basic knowledge to flares and energy release mechanism. In chapter two, the acceleration mechanism for non-thermal is recommended. In chapter three, electron acceleration by a super-Dreicer electric field Ez is investigated in the reconnecting current sheet with a guiding magnetic field Bz by applying test particle simulation. The guiding field is assumed constant within an RCS, but it have different direction which change the test particle trajectories and lead to the particles which leave the current sheet following field lines close to the different separatrix. In the presence of Bz parallel to Ez, the pitch-angle of energed particle close to180 degree. In contrast, if Bz anti-parallel to Ez, the pitch-angle close to 0 degree. The electric field will accelerate electron in different region due to the different direction of guiding field, but the effect to the distribution of electron energy is negligible. The energy spectrum of accelerated electron is universal with a power-law spectrum , and the value of spectra index have the relation with the strength of the guiding field, the scale of the current sheet, and the strength of electric field.
修改评论