A set of model equations of the dissipative trapped ion instability is derived and solved numerically. Multiple time scale expansion scheme is applied to the non-linear fluid equations of Kadomtsev and Pogutse by taking μ=ω⁄νe as a small parameter, where ω is the frequency of the wave and νe is the effective collision frequency of the electrons. All the modes except for the linearly most unstable one die away due to the mode coupling. Final saturation of the mode is attributed to the modification of background trapped ion number density averaged over the poloidal direction. The coefficient of trapped ion anomalous diffusion, which scales as D∝νia2 (νi is the effective collision frequency of the ions and a is the minor radius of a torus) is also derived.
ASJC Scopus subject areas
- General Physics and Astronomy