The stability of H+ and He++ ring distributions which have been observed downflowing into the cusp on the DE and S3-3 satellites is examined in the context of the feedback of those instabilities on plasma of ionospheric origin (H+ and O+). Lower hybrid waves are excited by the ring distributions in three distinct phases of wave-particle interaction: linear growth, trapping, and quasi-linear diffusion. The latter phase accounts for most particle heating. Including background O+ and/or a He++ ring introduces new modes not present in a pure H+ plasma which play an important role in heating heavier ions. O+ is heated significantly more by a He++ ring than a H+ ring of comparable energy density. It is suggested that lower hybrid waves generated by downflowing ion ring distributions play a role in energizing ion conics in the cusp.