Application of the Functional Method to the Study of the Stochastic Processes in Plasmas
Problems related to the transport processes in plasmas are often expressed as stochastic equations. We develop a formalism where the averages over statistical ensembles are obtained as functional integrations with appropriate measures. For a broad class of noise functions the calculation can be carried out analytically. The method has been successfully applied in the study of the particle motion in stochastic magnetic field and of the magnetic field line diffusion. We have obtained explicit results for the diffusion of particles in the presence of random trapping and for continuum time random walks with Levy distribution.