A closed-orbit suppression circuit for a Main Ring transversal damper

The signals of a transversal damper pickup usually have a certain number of common-mode components due to the off-center beam at the location. For the limit in the output power and the required minimum dynamic range of the feedback system, this common-mode component must be suppressed as much as possible. An analog front end is being developed for a transversal damper of the Main Ring at Fermilab (1) for this purpose. The front end features a balanced feedforward circuit and a possible single-ended negative feedback loop. Properly set, the time constant of the feedforward circuit ensures that the slowly changing closed-orbit component will be adaptively canceled, while the betatron oscillation components will survive in the output. copyright 1997 American Institute of Physics