The effects of vertical outflows on disk dynamos

We consider the effect of vertical outflows on the mean-field dynamo in a t hin disk. These outflows could be due to winds or magnetic buoyancy. We ana lyse both two-dimensional finite-difference numerical solutions of the axis ymmetric dynamo equations and a free-decay mode expansion using the thin-di sk approximation. Contrary to expectations, a vertical velocity can enhance dynamo action! provided the velocity is not too strong. In she nonlinear r egime this can lead to super-exponential growth of the magnetic field.