Unified theory of Alfven resonances and forced reconnection

Most of the plasmas encountered in space and laboratory are weakly collisional or collisonless, in the sense that diffusion time scales at macroscopic spatial scales are too long to explain the fast energy release as well as heating observed during explosive events, such as flares, geomagnetic storms and disruptions in magnetic confinement devices. For this reason, understanding the dynamical formation of quasi-singular boundary layers is fundamental to understanding explosive energy release as well as plasma heating and control. Alfven wave resonance and forced reconnection are two processes by which such boundary layers can be generated in inhomogeneous plasmas. In this project, we investigate these two processes in a unified theoretical and numerical framework. In particular, we investigate the transition from the Alfven wave resonance to forced reconnection by introducing a forcing that is parameterized through a main driving frequency, by considering both a monochromatic and a non-monochromatic spectrum. We determine the properties of the boundary layer and of the timescale required to form such a layer as a function of the forcing spectrum and of the Lundquist number. In future work we will extend our results to the fully nonlinear regime to investigate the stability of these boundary layers.