Preliminary Studies of a Phase Modulation Technique for Measuring Chromaticity

The classical method for measuring chromaticity is to slowly modulate the RF frequency and then measuring the betatron tune excursion. The technique that is discussed in this paper modulates instead the phase of the RF and then the chromaticity is obtained by phase demodulating the betatron tune. However, this technique requires knowledge of the betatron frequency in real time in order for the phase to be demodulated. Fortunately, the Tevatron has a tune tracker based on the phase locked loop principle which fits this requirement. A preliminary study with this technique has showed that it is a promising method for doing continuous chromaticity measurement and raises the possibility of doing successful chromaticity feedback with it