Nonlinear phase dynamics of ideal kink mode in the presence of shear flow

摘要

We investigate nonlinear phase dynamics of an ideal kink mode,induced by E×B flow.Here the phase is the cross phase(θ_(c))between perturbed stream function of velocity(f)and magnetic field(y),i.e.θ_(c)=θf−θψ.A dimensionless parameter,analogous to the R_(i)chardson number,R_(i)=16gkink w^(2)E^(2)(γkink:the normalized growth rate of the pure kink mode;wE:normalized E×B shearing rate)is defined to measure the competition between phase pinning by the current density and phase detuning by the flow shear.When R_(i)>1,θ_(c) is locked to a fixed value,corresponding to the conventional eigenmode solution.When R_(i).1,θ_(c) enters a phase slipping or oscillating state,corresponding to a nonmodal solution.The nonlinear phase dynamics method provides a more intuitive explanation of the complex dynamical behavior of the kink mode in the presence of E×B shear flow.