Evidence for the generation of current-driven ion-cyclotron instability in a plasma

Electrostatic ion-cyclotron oscillations are observed in the presence of an electric current passing through the entice cross section of the plasma column in a modified Q machine, where ion and electron sources with the same diameter are oppositely set at the machine ends. This means that it is not a two-dimensional potential structure but an electron drift that causes the oscillations, demonstrating the generation of a current-driven ion-cyclotron instability. In various respects the features of the instability are different from those of well-known ion-cyclotron oscillations induced by applying positive potentials to a small cold disc electrode immersed in a plasma column.