 |
Center for Nonlinear Studies |
Alpha particles in a burning plasma will resonate with shear Alfven waves, and the free energy will from the universal diamagnetic drift drive, may cause a weak instability. These waves, near the instability threshold are likely to be discrete, and the saturation mechanism needs to be understood. Perhaps the most interesting phenomena we have found in various saturation possibilities is spontaneous chirping. Rather than just getting a flattening near the resonant region, a phase space structure can form, that \'bores\' through the distribution, creating a phase hole or phase space clump. Various aspects of the theory, together with simulation results, will be presented. It is interesting, that this theory is generic to nearly any weak kinetic instability system, where the excited resonances do not overlap, with applications to the relatively simple bump-on-tail instability to Alfven waves driven in a tokamak.