[en] A fixed frequency 93 MHz harmonic cavity has been installed in the AGS ring. The primary purpose of this harmonic cavity is to increase (dilute) the longitudinal phase space area occupied by the beam by as much as a factor of four (to 4.0 eV-s) in a controlled, rapid manner while maintaining a smooth local density. This then will permit essentially lossless passage through transition energy (8.0 GeV) at intensities higher than previously achieved. Although the system controls permit as many as five dilutions per AGS cycle, only one is used at present. Effects of the various phase modulation programs, excitation period, and rf voltage programs on the dilution rate have been modeled. The parameters predicted to yield the best dilution have been implemented with satisfactory results. Further, a beginning has been made to explore the parameter space experimentally in order to determine the programs leading to the desired of dilution without loss of beam in the minimum time. 5 refs., 5 figs., 4 tabs