1. The problem statement, all variables and given/known data In a so called z-pinch the plasma is determined by: B =B0r/a θ^ where a is the pinch radius Calculate the drift velocity due a inhomogenous magnetic field and a bended magnetic field in ions with charge q and mass M in the pinch. Assume that that the ions in the plasma has a isotropic speed distribution with the speed sqrt(KT/M) per degree of freedom 2. Relevant equations V∇B = μ/(qB2)*(B x ∇B) VR = (mv||2)/(qBRc2)*(Rc x B) 3. The attempt at a solution From the solution manual i don't understand how they calculate the perpendicular and horizontal speed. This is what i don't get: Isotropic distribution of ions: 1/2M<v_2> = 2* KT/M <----- Why multiply with 2 ? and 1/2M<v||2> = 1 * KT/M <----- Why multiply with 1 ?