2.5 MHz feedforward beam loading compensation in the Fermilab main injector

There are five 2.5 MHz ferrite cavities (h = 28) in the Main Injector with an WQ of 500 that are presently used for coalescing for the Tevatron. For use with the Fermilab Recycler, feedforward (FF) beam loading compensation (BLC) is required on these cavities because they will be required to operate at a net of 2 kV. Under current Recycler beam conditions, the heam-induced voltage is of this order. Recently a system using a digital bucket delay module operating at 53 MHz (h = 588) was used to produce a one-turn-delay feedforward signal. This signal was then combined with the low level RF signal to the 2.5 MHz cavities to cancel the beam induced voltage. During current operation we have shown consistently to operate with over a 20 dB reduction in beam loading.