force_drift¶

plasmapy.formulary.drifts.force_drift(F: Unit(‘N’), B: Unit(‘T’), q: Unit(‘C’))¶

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
>>> from astropy.constants.si import g0, e, m_e
>>> ex = np.array([1, 0, 0])
>>> ez = np.array([0, 0, 1])
>>> force_drift(-ez*g0*m_e, ex*0.01*u.T, e)
<Quantity [ 0.0000000e+00, -5.5756984e-09,  0.0000000e+00] m / s>
>>> force_drift(-ez*g0*m_e, ez*0.01*u.T, e)
<Quantity [ 0., -0.,  0.] m / s>
>>> force_drift(-ez*g0*m_e, ex*u.T, e)
<Quantity [ 0.0000000e+00, -5.5756984e-11,  0.0000000e+00] m / s>

Returns: v – Drift velocity, in m/s
Return type: 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