Effective Masses of Ions in Superfluid $^3$He-B

We show that ion masses in superfluid $^3$He ought to be enormously enhanced (by a factor of 100) as compared with the same ion masses in $^4$He measured at low temperature. We calculate precisely the dependence of the effective mass on pressure in $^3$He-B, and show that the coherent (ballistic) motion of ions in $^3$He-B can be studied experimentally at $T < (0.3-0.2) T_c$.