The working principle involves the acceleration of an electrically conductive fluid (which can be a liquid or an ionized gas called a plasma) by the Lorentz force, resulting from the cross product of an electric current (motion of charge carriers accelerated by an electric field applied between two electrodes) with a perpendicular magnetic field. The Lorentz force accelerates all charged particles (positive and negative species) in the same direction whatever their sign, and the whole fluid is dragged through collisions. As a reaction, the vehicle is put in motion in the opposite direction.