Nonlinear radial oscillations in a pinch plasma under oscillatory external magnetic field and application to controlling internal flux

The nonlinear oscillatory behaviors of plasma and internal trapped magnetic flux in a pinched plasma under a forced oscillating external magnetic field are analyzed numerically, and it is found three kinds of stable radial oscillation mode; T1 and T2 periodic modes and intermittent chaotic one exist. For the case that a small amplitude oscillatory field component whose frequency satisfies the nonlinear resonant condition to radial oscillation mode is added, the flux trapped inside plasma increases remarkably, and its quantity reaches a saturation level whose value is more than 2.5 times as large as value maintained with only a crowbar field. Matching conditions between plasma and magnetic field to control the trapped flux by the resonance effect are obtained. (author)