Energetic charged particle transport and energization in dynamic two-dimensional turbulence

Quasi-linear theory has been used extensively to study the interaction of energetic particles with MHD fluctuations in the solar wind. However, in recent years there has developed a view that solar wind MHD turbulence can be modeled approximately as a dominating incompressible two-dimensional turbulence component combined with a minor one-dimensional parallel-propagating Alfven wave component (a one-dimensional slab component in the static limit). Here a quasi-linear theory is developed to investigate the effect of dynamical two-dimensional MHD turbulence in the solar wind on low-energy charged particle pitch-angle scattering and momentum diffusion. Stochastic acceleration by transverse two-dimensional turbulence electric field fluctuations is also considered, yielding finite momentum diffusion coefficients. We find significant effects by energy-containing-scale, dynamic two-dimensional turbulence on low-energy particles in the vicinity of 1 keV energies, and overall dominance of parallel-propagating Alfven waves at higher energies.