Common mode noise on the main Tevatron bus and associated beam emittance growth

Overlap of betatron tune frequencies with the power supply noise spectrum can cause transverse beam emittance growth in a storage ring. This effect has been studied for tunes near the integer, where the betatron frequency is low. By injecting noise onto the main power supply bus, it was determined that common mode noise was the dominant source of emittance growth. A noise suppression feedback loop was used to reduce the noise and the emittance growth. These experiments are described, as are investigations of the common mode propagation along with the Tevatron bus and measurements of the fields generated by common mode excitation of isolated Tevatron magnets.<
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