VELOCITY FLUCTUATIONS IN CORONAL LOOPS AS FLARE DRIVERS

摘要

We developed a new shell model (Hybrid Shell Model)rnbased on Reduced MHD, which describes the Alfv′enicrnturbulence inside a coronal loop, taking into account energyrninput through photospheric motions. Energy releasernevents in the corona are modelled as dissipative events inrnthe MHD turbulence. The model reproduces distributionsrnof released energy, peak power, duration, waiting time ofrncoronal events. The occurrence of high values (～100rnkm/s) of the large scale fluctuating velocity can represent rnan efficient trigger to nonlinear intermittent turbulent cascadernand then to the generation of a burst of dissipatedrnenergy. The model gives a physical explanation of thernreason why large velocity fluctuations represent the flarerntrigger rather than the result of the later energy deposition.