Booster High-level RF Frequency Tracking Improvement Via Bias-Curve   Optimization
  It is important to improve the frequency tracking between the RF drive and the cavity field for the purpose of reducing longitudinal phase oscillations and increasing the effective accelerating voltage. And this is especially beneficial for Booster running at higher intensity with smaller beam emittance. Optimizing the bias supply current curve for the ferrite tuners can reduce the phase error between the RF drive and the cavity field, and also improve the HLRF-to-LLRF frequency tracking efficiency. 
Xi Yang