Resonance Broadening Theory Revisited

摘要

It is shown that the velocity variance in one dimensional electrostaticturbulence is not pure Brownian but subdiffusive and increasing with time, with a corresponding diffusivity decreasing with time. The fractional Brownian motion associated with the diffusion process is attributed to non-Markovian statistics of particle trajectories. The anomalous spatial diffusivity across a sheared magnetic field caused by low frequency electric and/or magnetic fields is analogous to the velocity diffusivity and has the same scaling with the turbulence level and time. The theory has been tested favorably by numerical test particle simulations.