Neutral Hydrogen in the Jupiter–Iо Flux Tube

Abstract

The magnetohydrodynamic problem on the motion, thermodynamic parameters and space distribution of neutral hydrogen in the Jupiter–Io flux tube is solved. The plasma in the tube cross-section is shown to be compressed by the current-induced azimuth magnetic field and forms a stationary plasma column similar to the Z–pinch. For the “Voyager-1” recorded current magnitudes 6·10⁵ё3·10⁶ A the Io tube foots move as high as 900ё1100 km. The concentration of neutral hydrogen in their plasma makes about 10⁸ё10⁹ cm–3. With height the density of matter in a tube decreases making at the Iо height the 10^-6ё10^-7 part of the plasma density in the Io tube foots. The neutral hydrogen temperature in a tube differs little from the ambient medium temperature that is connected to rather small Joule heat evolution. Plasma can move along the tube axis only on the length which passes through the Io torus, its speed being about 100 km/s. Radial motion results in plasma escaping from the tube and dispersal in the circumambience within a radius of about 10,000 km. The results obtained correlate qualitatively with the spectroscopic data.