Magnetic Field Measurement and Analysis of the CSNS/RCS Quadrupole Magnets
The China Spallation Neutron Source/rapid-cycling synchrotron (CSNS/RCS) quadrupole magnets excited by both dc current and 25 Hz ac biased dc current were tested and measured in the past two years. All the magnets had been installed in the tunnel by the end of December, 2015. The challenges of the field measurements included the measurement repeatability of the dc field and the time harmonic measurement of the dc+ac field. The paper will summarize the results of the dc field measurement and the dc+ac field measurement, the key techniques of the rotating coil fabrication and the measurement stability for the CSNS/RCS quadrupole magnets.
Reduction of AC Loss in HTS Coils of Superferric Magnets for Rapid-Cycling Synchrotrons by Changing Cross-Section of Coils and Iron Yoke Geometry
We have been studying the potential of energy consumption reduction in rapid-cycling synchrotrons (RCSs) by using superferric magnets with coils wound with high temperature superconductor (HTS). By conducting three-dimensional electromagnetic field analyses on superferric magnets with different coil cross-sections and iron yoke geometries, ac loss of each magnet design was estimated. Rough estimations of the iron loss were also conducted to obtain overall energy consumption of each magnet design. By the comparison, influence of coil cross-section and iron yoke geometry on electricity consumption of the magnet were evaluated.
Field interference studies between bump magnets with different coil structures at Chinese Spallation Neutron Source
For magnets arranged so closely that the distance between them is comparable to the magnet apertures, the field interference becomes important. This is the case in the injection region at the China Spallation Neutron Source (CSNS) where several bump magnets are used to create fixed and dynamic local orbit bumps for the beam injection using the H(-) stripping and the phase space painting method. The reduction in the field integral due to the field interference will cause an orbit distortion, and the orbit bumps will be no longer localized. It is found that the end coil structure plays an important role in reducing the fringe field of a magnet. This has been analyzed by using both the image current method and three-dimensional magnetic field calculations. The saddle end coil instead of the compact end coil has been adopted at the CSNS. The relative reduction in the field integration after the optimization can meet the design requirement of about 1% or less.