Electron-proton collisions in plasma on magnetic white dwarfs

We analyze the motion of an electron in a strong, uniform magnetic field an d in the Coulomb electric field of a proton in the case where the electron gyroradius is smaller than the maximum impact parameter e(2)/kappa T, which corresponds to collisions with a large-angle scattering in the absence of a magnetic field. A new expression is derived for the effective frequency v (eff) of electron-proton collisions in a classical plasma. The standard rel ations for v(eff) are shown to be invalid in this case, which, in particula r, can be realized in the photospheres of magnetic white dwarfs. This facto r plays an important role in calculations of the radiative transfer and the radiation pressure force in the photospheres of these stars.