  It is shown that one can stimulate, by using the present-day laboratory
magnetic fields, transitions between the $lm$ sub-levels of fast $\mu He^+$
ions formating in muon catalyzed fusion. Strong fields also cause the
self-ionization from highly excited states of such muonic ions. Both effects
are the consequence of the interaction of the bound muon with the oscillating
field of the Stark term coupling the center-of-mass and muon motions of the
$\mu He^+$ ion due to the non-separability of the collective and internal
variables in this system. The performed calculations show a possibility to
drive the population of the $lm$ sub-levels by applying a field of a few
$Tesla$, which affects the reactivation rate and is especially important to the
$K\alpha$ $x$-ray production in muon catalyzed fusion. It is also shown that
the $2s-2p$ splitting in $\mu He^+$ due to the vacuum polarization slightly
decreases the stimulated transition rates.
