Noun
gyroradius (plural gyroradii)
(physics) The radius of the circular motion of a charged particle in the presence of a uniform magnetic field.
The radial magnetic field is designed to be strong enough to substantially deflect the low-mass electrons, but not the high-mass ions, which have a much larger gyroradius and are hardly impeded. Source: Internet
However, the gyroradius in those circumstances is also larger, so that the radial component of the magnetic field seen by the particle is also larger. Source: Internet