Slow feedback loops for a Landau cavity with high beam loading

Equilibrium bunch shapes for bunches stretched with a higher-harmonic cavity are sensitive functions of beam and RF parameters. This paper gives results of calculations of equilibrium bunch shapes as a function of Landau-cavity phase, the relationship between the stretched-beam phase and slow feedback controls for the cavity is described, and a control system capable of stretching, compressing, controlling the cavity phase arbitrarily (within the limits of the power amplifier), and operating without beam for use in the NSLS Vacuum-Ultraviolet (VUV) ring is presented. The last is compared with the existing RF controls for the VUV-ring harmonic cavity