EXCITATION OF ALFVEN WAVES AND LOCAL TURBULENCE BY ENERGETIC ION-BEAMS IN SOLAR-FLARES

Solar flares release a large part of their energy in the form of beams of high - energy particles. Energetic ion beams can excite Alfven waves when the beam velocity is greater than the Alfven speed. In turn, the Alfven waves can be unstable with respect to secondary Kelvin - Helmholtz instabilities, which produce turbulence and limit the Alfven wave amplitude. In this way, the ion beam leads to the production of fluid turbulence. The turbulence is strong enough to limit the waves to an energy density which is small compared to the beam energy density. However, the turbulent resistivity produced by the waves and secondary instability is many orders of magnitude larger than molecular resistivity. The turbulence may enhance reconnection, triggering more flares.