Bounce effects on the cyclotron instability caused by trapped alpha particles in tokamak reactors

The role of bounce resonances in the cyclotron build-up of fast magneto-acoustic waves, by trapped alpha particles in a tokamak reactor is investigated theoretically. It is shown that bounce resonances can cause a further increase in the growth rate of fast magneto-acoustic waves by a magnitude of the order of 0.5 ( ω BS /ω b ) 1/3 , where ω BS is the mean cyclotron frequency of alpha particles on the magnetic surface, ω b is their bounce frequency and is the ratio of the minor and major radii of the tokamak.