2020同步年報

Facility Status 095 Fig. 1 : The flow chart of the global tune feedback in TPS. Fig. 2 : Tune shift caused by six IU moving simultaneously around minimum gap, the global tune feedback is off. statistical behavior (histogram) was then calculated. The histogram of the measured tunes from the BBF was fitted with a Gaussian function, from which the mean and standard deviation σ were derived. If the tune difference is greater than 2σ and smaller than 0.01, the tune difference is treated as a truly significant signal; otherwise it is ignored. The global tune feedback system uses the tune difference and the model tune re- sponse matrix to calculate the correc- tion currents ∆I with singular value decomposition (SVD) and then applies to the quadrupoles of QD1S and QF2S families iteratively till the tune differ- ence is smaller than 2σ. The flow chart of the global tune feedback is depicted in Fig. 1 . 1,2 Initial- ly, if the electron beam is tripped, the tune feedback stops. If the storage ring is in injection, the tune feedback is skipped; otherwise the tune differ- ence is tested if the signals are truly significant (2σ < Δν < 0.01). If they are, the tune difference will be used to calculate the correction currents which will be applied to the quadrupoles of QD1S and QF2S families iteratively by the equation 2, till the tune deviations are brought back to the working point within a tolerance of 2σ.