  We determine the conditions of formation of spontaneous polarization phase
transition to the superradiance regime in the inverted system of
nonrelativistic electrons on equidistant Landau levels in rarefied magnetized
plasma. The possibility of realization of such conditions in the lower Jupiter
magnetosphere is shown. The effect of cyclotron superradiance on the Landau
levels gives a key to interpretation of the nature of superpower radioemission
of the Jupiter-Io system.

Atomic Physics;Space Physics