Nonlinear evolution and energy dissipation in shear-driven collisionless plasma turbulence

Turbulence is often driven by velocity shears or temperature gradients. Previous studies have emphasized shear-driven plasma dynamics initiated by linear (Kelvin–Helmholtz) instability and leading to saturation due to vortex roll-up. For the collisionless plasma case, small-scale kinetic effects responsible for energy conversion and dissipation have been studied in fully developed turbulence and in magnetic reconnection; here, this analysis is applied to velocity shear-driven turbulence using particle-in-cell simulations. An emphasis is on the description of evolving turbulent characteristics in relation to dissipation and coherent structures. The results quantify partitioning between electron and proton heating as well as the spatial intermittency of dissipation for each species. The results may be relevant to interpretation of Magnetosphere Multiscale mission data and Parker Solar Probe measurements in regions where unequal proton–electron heating as well as shear-driven turbulence may be present.