Consequences of strong pitch-angle diffusion of particles in solar flares

Abstract

The consequences of strong pitch-angle diffusion of energetic electrons and ions during the impulsive phase of a solar flare have been analyzed. Strong diffusion suggests that the regions with high levels of small-scale turbulence (turbulent mirrors) are formed in the magnetic trap. These additional mirrors scatter the energetic particles, and therefore, the propagation velocity of the particles toward the footpoints decreases. It has been shown that the strong diffusion of energetic particles by waves is realized very easily in a flare loop. The main consequences of strong pitch-angle diffusion are as follows: (1) the turbulent propagation time for greater than about 10 MeV ions is about one order of magnitude longer than for greater than about 30 keV electrons, (2) the energetic particle spectra in a flare loop reflect the source particle spectrum, and (3) the energetic particle density is constant along the flare loop axis. The strong diffusion approach makes it possible to explain, for example, the time delays in hard X-ray and gamma-ray emission and the properties of particle fluxes in the interplanetary space, and it offers new possibilities for flare plasma diagnostics. 17 refs.