Implicit particle simulation of vortex coalescence in an electrostatic plasma

Summary Form only given, as follows. Using an implicit particle-in-cell simulation code with a novel particle weighting scheme that initializes a driving flow field, the numerical simulation of the coalescence of vortices in an electrostatic plasma has been performed and a comparison of a theoretical model with point vortices has been made. Special attention has been given to the limiting case of a purely sheared flow field, which gives rise to the Kelvin-Helmholtz instability, and a simpler numerical theory involving eigenvalues of the Rayleigh equation is developed for comparison. Good agreement is found. Experimental observations have shown that linearly stable modes can be nonlinearly destabilized by the growth of linearly unstable modes and that, after coalescence, vortices can pass through each other and separate again, leading to an oscillatory coalescence process.<>