@honeste_vivere, In the case of cle orbiting around a massive object such as the near the planets like Jupiter, Saturn etc the plasma drag, however small, do influence the its evolutions and dynamics. Even if there is no direct impact/collision 'coulomb drag' of the plasms too influence the charge dynamics and cannot be neglected. However, Plasma drag due to collsions and coulomb drag have similar expression except that the coulomb drag is much larger.

@KyleKanos, The reason I asked is to be able to find the drag/force for a particle moving along any direction. For instance, the plasma is at the origin of a Spherical polar Frame and pass through it at some radial distance, at ang co-latitude angle (θ) = 45degree and azimulth angle (ϕ) =60degree. How would I incorporate it in the drag equation?

The reason I asked is to be able to find the drag/force for a particle moving along any direction. For instance, the plasma is at the origin of a Spherical polar Frame and pass through it at some radial distance, at ang co-latitude angle (theta) = 45degree and azimulth angle (phi) 45degree. How would I incorporate it in the drag equation?

The scattering angles both for large and small one, Impact parameter, only affect the strength of the force not the nature of the force.

What would be the components of the forces along R, theta and phi?

Thank you for your response. Almost in all papers they always gives the scalar expression but not the vector form.