From the January 2010 issue

Do Io’s volcanic eruptions create the electromagnetic torus between the moon and Jupiter? Could Io deorbit into Jupiter in the next several million years because of energy lost in these interactions?

Douglas Kaupa, Edwards Air Force Base, California
By | Published: January 25, 2010
March 2010 Jupiter-Io
The Jupiter-Io plasma torus (in red) is a result of Jupiter’s magnetic field sweeping up material from Io’s volcanic eruptions. As Io moves through the torus, interactions between Io and Jupiter power a huge electrical current that extends from one body to the other. This flux tube is shown in green.
John Spencer

There is no danger that Io will spiral down into Jupiter on a timescale of several million years.

Io’s volcanic eruptions do not create the electromagnetic torus. But they do contribute material to it.