Combined Release and Radiation Effects Satellite (CRRES) Electric Field Instrument (EFI) data are used to determine the electric field power spectral density as a function of L and Kp over the frequency range 0.2 to 15.9 mHz. The power at each frequency is fit to the function P(L, Kp) = a Lb exp(cKp). Assuming a purely electrostatic field and making several other assumptions regarding the azimuthal dependence of the field fluctuations, a Kp-dependent radial diffusion coefficient DLLE is computed from the power spectra. The model average DLLE for high activity (Kp = 6) are between 1 to 2 orders of magnitude larger than that for low activity (Kp = 1), dependent upon L and first invariant.