Nonlinear 3‐D evolution of bounded kinetic Alfven waves due to shear flow and collisionless tearing instability

The three‐dimensional nonlinear simulation of the evolution of a kinetic Alfven wave is presented for simple boundary conditions that resemble those of a discrete auroral breakup arc. The model used is a variant of the reduced magnetohydrodynamic description that includes, in addition, the important dispersive effect of electron inertia. It is found that with a "generator" boundary condition corresponding to a current generator and a fully conducting "load" boundary, the wave evolves three dimensionally through a combination of shear flow and collisionless tearing mode instability.