Large-system behavior of the nonlinear drift-kink instability in relativistic pair plasma

The drift-kink instability (DKI) can destabilize current sheets, especially in electron-positron pair plasma, releasing magnetic energy and energizing particles. The DKI has been shown, at least in moderately-sized systems, to yield particle acceleration akin to that in magnetic reconnection, potentially capable of powering high-energy flares in astrophysical sources such as pulsar wind nebulae. Using 2D particle-in-cell simulation, we characterize the large-system evolution of DKI-destabilized current sheets, and compare to 2D reconnection. In its linear stage, the DKI causes the current sheet to ripple; in the nonlinear stage, the current sheet folds over on itself, rapidly releasing magnetic energy as it thickens. The thicker sheet slows linear DKI growth, but favors longer wavelengths that ultimately release correspondingly more energy in the nonlinear stage. While a model relying on the linear theory predicts this process will scale to arbitrarily large systems, simulations suggest that the process slowly saturates. Thus, unlike magnetic reconnection, which continues unabated for arbitrarily long times in large-enough systems, the DKI cannot by itself dissipate a substantial fraction of magnetic energy in astrophysically-large systems in as short a time as reconnection.