GALILEO PLASMA-WAVE OBSERVATIONS IN THE IO PLASMA TORUS AND NEAR IO

The Galileo plasma wave instrument detected jovian radio emissions, na rrowband upper hybrid waves, and whistler-mode emissions during the in bound pass through the to torus. The upper hybrid waves provided an ac curate profile of electron density through the Io torus and in the vic inity of Io. These measurements show that the torus density has increa sed by about a factor of 2 since the Voyager 1 flyby in 1979. A well-d efined peak in the electron density was observed in the wake of to, wi th densities as high as about 4 x 10(4) per cubic centimeter.