On anomalous diffusion in a plasma in velocity space

The problem of anomalous diffusion in momentum space is considered for plasmalike systems on the basis of a new collision integral, which is appropriate for consideration of the probability transition function (PTF) with long tails in momentum space. The generalized Fokker–Planck equation for description of diffusion (in momentum space) of particles (ions, grains, etc.) in a stochastic system of light particles (electrons or electrons and ions, respectively) is applied to the evolution of the momentum particle distribution in a plasma. In a plasma the developed approach is also applicable to the diffusion of particles with an arbitrary mass relation due to the small characteristic momentum transfer. The cases of an exponentially decreasing (including a Boltzmann-like) kernel in the PTF in momentum space, as well as more general kernels, which create anomalous diffusion in velocity space due to the long tail in the PTF, are considered. Effective friction and diffusion coefficients for plasmalike systems are found