Electron Energy Partition in the Above-the-looptop Solar Hard X-ray Sources

The presentation begins by considering the non-thermal fraction of electron energies (Re) in 'above-the-looptop' (ALT). Several spectral models area considered: isothermal model, power-law, and the newly derived kappa distribution. Technically, all 3 non-thermal models can fit the data. In the discussion of flare scenario, energy partition, energization mechanism, and collisionality are considered. It is concluded that the kappa distribution works (Re ≲ 50%), magnetic reconnection scenario works, and Coulomb collisions may reduce the non-thermal fraction of electron energies.