Brownian motion of grains and negative friction in dusty plasmas

摘要

Within the approximation of dominant charging collisions the explicit microscopicudcalculations of the Fokker-Planck kinetic coefficients for highlychargedudgrains moving in plasma are performed. It is shown that due toudion absorption by grain the friction coefficient can be negative and thus theudappropriate threshold value of the grain charge is found. The stationaryudsolutions of the Fokker-Planck equation with the velocity dependent kineticudcoefficient are obtained and a considerable deviation of such solutionsudfrom the Maxwellian distribution is established.