- The Fokker-Planck coefficients are developed for an ion-electron plasma in an ambient uniform magnetic field. The calculation is based on the binary collision model where a single encounter between an ion and an electron is first considered. The collision is taken as a perturbation to the free helical motion of the two particles involved, and the terms are kept up to the second order. The collision process is reformulated in terms of the changes of the perpendicular and parallel speeds and gyrophase shift. This new approach allows us to properly take into account the persisting helical motion in the magnetic field when the collisional interaction ceases.