Kelvin-Helmholtz Vortex Formation and Particle Transport in a Cross-Field Plasma Sheath

The time-dependent behavior of a magnetized, two-dimensional plasma-wall sheath has been studied through particle simulations, which have shown that the cross-field sheath develops into a turbulent boundary layer, driven by the Kelvin-Helmholtz instability. The sheath acquires an equilibrium thickness $l_x\sim 5{\rho }_i$, and maintains long-lived vortices, with amplitudes $\delta \phi \sim -\frac{2T_i}{e}$, which drift parallel to the wall at half the ion thermal velocity. A central simulation result is that for ${\omega }_{\mathrm{pi}}\ge 2{\omega }_{\mathrm{ci}}$, the anomalous particle transport in the sheath scales like Bohm diffusion.