Large-scale energy balance and MHD turbulence in solar coronal structures

The energy balance at large scales in a coronal loop is studied, using an analytical model. We generalize a previous model by including a longitudinal inhomonegeity in the background density. The dynamics is regulated by the resonance between motions at the loop basis and eigenmodes, giving rise to energy storage within the loop, and by nonlinear effects that move this energy to smaller scales. We derive a scaling law for the input energy flux, the properties of eigenmodes and of their nonlinear coupling, and estimations for the nonlinear flux and for the velocity perturbation. For typical loop conditions, the resulting values are in accordance with the energy flux required for the quiet-Sun corona and with measured nonthermal velocities.