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.
A harmonic coil measurement system based on a dynamic signal acquisition device
Abstract A new harmonic coil measurement system based on a dynamic signal acquisition device has been successfully developed to check the field quality of the quadrupole magnet for the CSNS/RCS, which operates at the 25 Hz excitation cycle with a DC bias. It was designed to acquire multiple channels of data with a wide dynamic range of input signals, which are typically generated by a harmonic coil and an encoder. A dedicated algorithm was developed in LabView code to identify over specified intervals, synchronized to the coil’s rotation in the magnetic field. Through full integration of hardware and software, the traditional device (PDI 5025) is replaced successfully. This paper summarizes the characteristics of the system and presents the results of DC measurements.
Field Measurement of DC Magnets at 3-GeV RCS in J-PARC
The J-PARC RCS (rapid cycling synchrotron) is designed to inject the beam from the LINAC, to change their charge from to , to accelerate the beam from 400 MeV to 3 GeV, with protons per pulse at 25 Hz repetition rate, and to extract the beam after the acceleration to the MLF (material and life science experimental facility) and the MR (main ring). Thus the RCS has the beam circulating ring and three beam transport lines. The RCS ring consists of several magnets, and the DC magnets are installed for beam injection and extraction. The four steering magnets and two septum magnets are installed at injection line in order to adjust the beam injection point. One quadratic magnet, two steering magnet and two septum magnets are installed at dump line for the part of the beam with their charge not changed from to at the charge stripping foil. Two deflecting magnets to kick out the beam without exciting the pulse kicker magnets and three septum magnets are installed at the extraction line. Up to now, the DC magnets are developed and manufactured, the field measurements are carried out, and magnets installation into the RCS tunnel are finished. The field distributions of DC magnets are measured by using the new field mapping system with three one-dimensional hall-probes on a 3-axis movable stage. In the case of the quadrupole magnet, the field measurements are not only field mapping but also analyze its magnetic higher order components by the harmonic rotating coil. As a result, the measured field quality meets the design performance requirements of the DC magnets.