water and hydroxyl (OH) radicals (a product of water's dissociation) form a rather thick torus around the moon's orbit at 4 Rs with densities up to 10,000 molecules per cubic centimeter. At least 100 kg/s of this water is eventually ionized and added to the co–rotating magnetospheric plasma. Additional sources of water group ions are Saturn's rings and other icy moons. The Cassini spacecraft also observed small amounts of N+ ions in the inner magnetosphere, which probably originate from Enceladus as well. In the outer parts of the magnetosphere the dominant ions are protons, which originate either from the Solar wind or Saturn's ionosphere. Titan, which orbits close to the magnetopause boundary at 20 Rs, is not a significant source of plasma. The relatively cold plasma in the innermost region of Saturn's magnetosphere, inside 3 Rs (near the rings) consists mainly of O+ and O2+ ions. There ions together with electrons form an ionosphere surrounding the saturnian rings. For both Jupiter and Saturn, transport of plasma from the inner to the outer parts of the magnetosphere is thought to be related to interchange instability. In the case of Saturn, charge exchange facilitates the transfer of energy from the previously hot ions to the neutral gases in the inner magnetosphere. Then, magnetic flux tubes loaded with this newly cold, water–rich plasma interchange with flux tubes filled with hot plasma arriving from the outer magnetosphere. The instability is driven by centrifugal force exerted by the plasma on the magnetic field. The cold plasma is eventually removed from the magnetosphere by plasmoids formed when the magnetic field reconnects in the magnetotail. The plasmoids move down the tail and escape from the magnetosphere. The reconnection or substorm process is thought to be under the control of the solar wind and Saturn's largest moon Titan, which orbits near the outer boundary of the magnetosphere. In the magnetodisk region, beyond 6 Rs, the plasma within the co–rotating sheet exerts a significant centrifugal force on the magnetic field, causing it to stretch. This interaction creates a current in the equatorial plane flowing azimuthally with rotation and extending as far as 20 Rs from the planet. The total strength of this current varies from 8 to 17 MA. The ring current in the saturnian magnetosphere is highly variable and depends on the solar wind pressure, being stronger when the pressure is weaker. The magnetic moment associated with this