A method and system for stably generating and accelerating magnetized plasma comprises ionizing an injected gas in plasma generator and generating a formation magnetic field to form a magnetized plasma with a closed poloidal field, generating a reverse poloidal field behind the magnetized plasma and having a same field direction as a back edge of the closed poloidal field and having an opposite field direction of the formation magnetic field, and generating a pushing toroidal field that pushes the reverse poloidal field against the closed poloidal field, thereby accelerating the magnetized plasma through a plasma accelerator downstream from the plasma generator. The reverse poloidal field serves to prevent the reconnection of the formation magnetic field and closed poloidal field after the magnetized plasma is formed, which would allow the pushing toroidal field to mix with the closed poloidal field and cause instability and reduced plasma confinement.