Excitation of ion-cyclotron waves by a spiralling ion beam in a plasma cylinder

A helical ion beam propagating through a plasma cylinder drives electrostatic ion-cyclotron waves to instability via cyclotron interaction. Higher harmonics of the beam cyclotron frequency can be generated in this way. The growth rate increases with the harmonic number. The efficiency of beam energy transfer to the wave can be of the order of a few per cent. (author)