LONG TIME INCOMPRESSIBLE 2D MHD SIMULATIONS OF CORONAL LOOPHEATING: THE ROLE OF PHOTOSPHERIC TIME-SCALES

摘要

We investigate the long time statistical behavior of a twodimensionalrnsection of a coronal loop subject to magneticrnforcing through a two-dimensional reduced MHD approach.rnThe response of the loop a) to constant time forcingrnb) to random forcing with variable coherence times isrnstudied and compared via the time series of the averagernenergy dissipation and the spectral and spatial distributionsrnat a given time. The simulations show how for veryrnslow photospheric driving the magnetic field in the looprnself-organizes at large scales via an inverse MHD cascade,rnbut when the forcing then changes the loop mustrnrelax again, and each of these relaxation events yieldsrnbursts in the power dissipation. In the constant forcingrncase we study how dissipation scales with resistivity. Finallyrnwe discuss the implications for fully 3D simulationsrnof coronal heating.