  For NOvA and future experiments requiring high intensity proton beams,
Fermilab is in the process of upgrading the existing accelerator complex for
increased proton production. One such improvement is to reduce the Main
Injector cycle time, by performing slip stacking, previously done in the Main
Injector, in the now repurposed Recycler Ring. Recycler slip stacking requires
two new RF cavities operating at slightly different frequencies (df = 1260Hz).
These are copper, coaxial, quarter wave cavities with R/Q =13 ohms. They
operate at a peak gap voltage of 150 kV with 150 kW peak drive power (60% duty
factor), and are resonant at 52.809 MHz with a 10 kHz tuning range. Two have
been completed and installed. The design, high power test results, and status
of the cavities are presented.
