Generation of waves at the ion cyclotron frequency and its harmonics (ICRF) may be useful for fuelling as well as heating the high-energy and high-density mirror end plugs required by a tandem mirror. Fuelling may be accomplished by trapping the ions that are ejected from the centralcell electrostatic well as they flow out through the end plugs. It is shown that for a reasonable level of RF power this trapping can be quite efficient. Furthermore, for a fixed RF power level the trapping efficiency is seen to be adjustable by tuning the wave frequency.