THE DYNAMICS OF CHARGED-PARTICLES IN TURBULENT ASTROPHYSICAL PLASMAS

We consider the resonant interaction of energetic charged particles an d transverse plasma wave propagating parallel and/or antiparallel to t he uniform magnetic field B-0 in an underlying background plasma of de nsity n. The coupling of the plasma waves and the energetic particles will be controlled by the ratio n/\B-0\(2). A variation of this ratio leads to a strong variation of the dynamics of the energetic particles . By taking into account the whole transverse plasma branch for the re sonant interaction we discuss the influence of the background plasma d ensity, the background magnetic field, the cross helicity, and the mag netic helicities on the dynamics of charged particles in astrophysical plasmas. It is shown that low-energy electrons can be accelerated eff iciently by the higher electromagnetic waves and short-wavelength whis tlers for low values of the ratio n/\B-0\(2), which means for low valu es of the ratio of plasma frequency to gyrofrequency.