Splitting of drift shells by the magnetospheric electric field

The dawn-to-dusk magnetospheric electric field E breaks the pitch angle degeneracy of particle drift shells in a magnetic dipole field. For particles of sufficiently large kinetic energy T, the expression for the associated radial-diffusion coefficient is DL ≈ (μ02/162) (qEa/T)2 L04Dμ, where μ0 is the cosine of the equatorial pitch angle at midnight, q is the charge, a is the radius of the earth, and L0 is the dimensionless shell parameter. The coefficient of pitch angle diffusion Dμ is roughly half the reciprocal lifetime. In the absence of pitch angle scattering, the electric splitting of drift shells constitutes an important adiabatic phenomenon.