Study Of Correlation Analysis Of Global Data From A Storage Ring

Beam diagnostics system is one of the most important components of a particle acceleratorduring the commissioning, the operation and the machine study. It consists of severalsub-systems which measure various parameters of the bunches, including the beam currentmeasurement, the beam position measurement and the bunch size measurement systems.Traditionally,eachinstrumentistreatedindividuallysothatdiferentbeamparametersat diferent moments and on diferent locations could be measured continuously. Onlyparts of the raw signals would be used to obtain the resultant measurement by applyingsimple arithmetic operations. The downside is obvious: the precision of the measurementis determined by the probe and its corresponding electronics, which are limited by theelectronics development and the manufacturing of the probe. Even probes of the same typemight have diferent mismatching tolerances and the confdential intervals could hardlybe obtained based on the results of the measurements. Hence, one could not easily tellthe vibration in the signal is due to the malfunction, the disturbance of other local noisesources or the actual beam activities.This article focuses on the physics that the whole beam diagnostics system could beregarded as a super device with enormous probes. The signals from various traditionalprobes are diferent aspects of a single measurement procedure. The correlation analysis ofthe overall signals fts the characteristic function such as the function and the dispersionfunction to the data, which would efectively increase the usage of the original informationand promote the accuracy, reliability and feasibility of the output results.The transverse motion of the charged particles, the exponential damping of the bunchcharge and the relationship between the bunch distribution and its lifetime are combinedas the constraint conditions during the theoretical and experimental correlation analysis.Meanwhile, theModel-IndependentAnalysis(MIA)methodwouldbeusedaswellasotheranalysismethodsonthestorageringoftheShanghaiSynchrotronRadiationFacility(SSRF.)A global warehouse keeps the beam diagnostics data and other essential informationaccumulating, and bunch parameters—such as positions, charges and sizes—would bestudied ofine before everything goes real time.The experiments in SSRF show that the applications of the beam diagnostics systemcould be widen by using the correlation analysis without upgrading the hardware. MIAcould simultaneously measure thefunction and the dispersion function and locate the BPM malfunctions. The correlation between the sum signals of the BPMs and the DCsignal of the DCCT could signifcantly improve the resolution of the sum signals inDC measurements. The analysis of the transverse beam sizes and the beam lifetimeconfrmstherelationbetweentheTouschekfactorandthebeamstability. Andthemagneticfeld of the injector could be reconstructed by analyzing the transient motions in thebunch-by-bunch data.