– are significant sources of new plasma. The absorption of energetic electrons and ions reveals itself by noticeable gaps in the radiation belts of Saturn near the moon's orbits, while the dense rings of Saturn eliminate all energetic electrons and ions closer than 2.2 RS, creating a low radiation zone in the vicinity of the planet. The absorption of the co-rotating plasma by a moon disturbs the magnetic field in its empty wake—the field is pulled towards a moon, creating a region of a stronger magnetic field in the near wake. The three moons mentioned above add new plasma into the magnetosphere. By far the strongest source is Enceladus, which ejects a fountain of water vapor, carbon dioxide and nitrogen through cracks in its south pole region. A fraction of this gas is ionized by the hot electrons and solar ultraviolet radiation and is added to the co-rotational plasma flow. Titan once was thought to be the principal source of plasma in Saturn's magnetosphere, especially of nitrogen. The new data obtained by Cassini in 2004–2008 established that it is not a significant source of nitrogen after all, although it may still provide significant amounts of hydrogen (due to dissociation of methane). Dione is the third moon producing more new plasma than it absorbs. The mass of plasma created in the vicinity of it (about 6 g/s) is about 1/300 as much as near Enceladus. However, even this low value can not be explained only by sputtering of its icy surface by energetic particles, which may indicate that Dione is endogenously active like Enceladus. The moons that create new plasma slow the motion of the co-rotating plasma in their vicinity, which leads to the pile-up of the magnetic field lines in front of them and weakening of the field in their wakes—the field drapes around them. This is the opposite to what is observed for the plasma-absorbing moons. The plasma and energetic particles present in the magnetosphere of Saturn, when absorbed by ring particles and moons, cause radiolysis of the water ice. Its products include ozone, hydrogen peroxide and molecular oxygen. The first one has been detected in the surfaces of Rhea and Dione, while the second is thought to be responsible for the steep spectral slopes of moons' reflectivities in the ultraviolet region. The oxygen produced by radiolysis forms tenuous atmospheres around rings and icy moons. The ring atmosphere was