The Io-control of Jupiter's decametric radiation: The Alfvén wave model

Geometrical considerations based on a conical sheet model of the observed DAM sources show that DAM is generated on field lines in the active longitude sector φ ～ 200 ± 90°. We show how Io excites Alfvén waves and calculate the propagation of these waves through the inhomogenous torus and magnetosphere. The power flux at high latitudes is largest at two longitudes which are seen as the B₁, B₂, A and C sources. We also discuss the parallel electric field accompanying the Alfvén wave pulses and show that at high latitudes electrons can be accelerated to energies in excess of 1000 eV. It is suggested that these current carrying electrons excite ion-cyclotron, upper and lower-hybrid electrostatic waves which may all play crucial roles in the generation of DAM.