Stability of multicharged vortices in a model of superflow

In the framework of the nonlinear Schrödinger equation (NLSE) as a model of superflow we found that multicharged vortices are very long-living objects, contrary to the accepted opinion. The lifetime of these entities is inversely proportional to the dissipation rate which can be incorporated phenomenologically into NLSE. We calculated unstable eigenvalues and corresponding eigenfunctions. The nonlinear stage of the instability is studied numerically. We discuss the implications of our observation in the context of spin-up, flow past a body, and turbulence experiments in a superfluid helium.