# Homework Help: Drift velocity

1. May 28, 2015

### Firben

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 ?

2. Jun 2, 2015

### Staff: Admin

Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?

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