Chromaticity Measurements via RF Phase Modulation and Continuous Tune Tracking

Chromaticity diagnostics with high time resolution is of paramount importance for the control of the dynamic events in various accelerators, in particular for the LHC collider. This paper describes the possibility of measuring the machine chromaticity via RF phase modulation and continuous tune tracking. The RF phase modulation can be done at much higher frequencies than a classical RF frequency variation and thus, allows chromaticity measurements with a time resolution below the second. The paper describes the general measurement principle and discusses in detail open questions, which still have to be addressed experimentally. First results from machine measurements in the CERN SPS on beam stability during RF phase modulation are presented.