Subsecond X-ray Spikes in Solar Flares: Kinematics of Acceleration and Transport of Accelerated Electrons

Abstract

Hard X-rays time structure of solar flares can be caused by the timing of electrons acceleration, the kinematics of their propagation in the flaring plasma, and possible changes in plasma parameters and the loop magnetic field. In this paper the subsecond hard X-ray emission features were studied in a model of collapsing magnetic trap. The injection of 50-millisecond pulses of accelerated electrons in looptop with specified distributions of plasma density and magnetic field structure was considered. The magnetic field fluctuations and ion-acoustic turbulence influence on the fine time structure of hard X-ray emission was shown. The simulation results that it is possible to observe a super-thin time structure in the hard X-ray emission from accelerated electrons only if: ion-acoustic turbulence develops in magnetic loops and/or the pitch-angular distribution of electrons is sharply anisotropic. Moreover, the amplitude of individual spike is greater for harder electron spectra.