Simulation of turbulent pinch of a dipoleconfined plasma

Turbulence-induced inward diffusion and pinch effects are broadly investigated in the spatial magnetosphere [1, 2] and laboratory magnetic dipole experiments [3, 4]. The magnetohydrodynamic equations are obtained through bounce-averaged drift Hamiltonian and kinetic equations. Two key parameters, $\beta$ and $\eta$, determined by the density and pressure profile, characterize the interchange and entropy mode instability in linearized magnetohydrodynamic equations. They are discussed to distinguish the growth of the instability when a plasma is confined by a levitated magnetic dipole trap. Whole-device simulations are conducted in the equatorial plane using a flux-tube-averaged fluid model. The nonlinear, self-consistent evolution reveals the critical phenomenon of inward particle pinch and a centrally peaked profile caused by global convective cells. The nonlinear saturated states are marginally stable, as estimated by the two key parameters.