Frequency with which charged particles spin around a magnetic field line.
The force F exerted on a particle of charge q travelling at a velocity v in a magnetic field B is given by
F=q(v curl B)
Since this force is perpendicular
to both the magnetic field and the particle velocity, it results in a spiral
motion around the magnetic field at the cyclotron frequency ωc
where m is the particle mass
. (See Larmor radius writeup for more details).
Thus, a strong magnetic field produces fast spinning ions
, though ions will spin less frequently due to their greater mass.
Oscillations at the cyclotron frequency occur, naturally enough, in cyclotrons, and in plasmas.