# force_drift¶

plasmapy.formulary.force_drift(F: Unit("N"), B: Unit("T"), q: Unit("C")) -> Unit("m / s")

Calculate the general force drift for a particle in a magnetic field.

Aliases: vfd_

Parameters: F (Quantity) – Force acting on particle B (Quantity) – Magnetic field q (Quantity) – Particle charge

Examples

>>> import astropy.units as u
>>> ex = np.array([1, 0, 0])
>>> ey = np.array([0, 1, 0])
>>> ExB_drift(ex * u.V/u.m, ey * u.T)
<Quantity [0., 0., 1.] m / s>
>>> ExB_drift(ex * u.V/u.m, ex * u.T)
<Quantity [0., 0., 0.] m / s>
>>> ExB_drift(ex * u.V/u.m, 100 * ey * u.T)
<Quantity [0.  , 0.  , 0.01] m / s>

Returns: v – Drift velocity, in m/s Quantity

Notes

The particle drift in a magnetic field and with a general force (e.g. gravity) applied to it is given by

$\vec{v} = \frac{\vec{F} \times \vec{B}}{q |B|^2}$

Note the charge dependency.

References

• PM Bellan, Fundamentals of Plasma Physics, 3.58