  Radiation reaction acting on a charged particle moving at a stable circular
orbit of a magnetized black hole can lead to the shift of the orbital radius
outwards from the black hole. The effect causes increase of the energy and
angular momentum of the particle measured by an observer at rest at infinity.
In this note we show that "widening" of such orbits is independent of the field
configuration, however, it appears only in the cases with the external Lorentz
force acting outwards from the black hole. This condition corresponds to $q L B
> 0$, where $q$ and $L$ are the charge and angular momentum of the particle and
$B$ is intensity of the external magnetic field. As examples of the orbital
widening we consider two scenarios with an external homogeneous magnetic field
and a magnetic dipole field generated by a current loop around a Schwarzschild
black hole. We show that the orbital widening is accompanied by quasi-harmonic
oscillations of the particle which are considerably large in the magnetic
dipole fields. We also estimate the timescales of orbital widening from which
it follows that the effect can be relevant in the vicinity of stellar mass
black holes.
