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.
Field Measurement of the Quadrupole Magnet for CSNS/RCS
The quadrupole magnets are being manufactured and measured for China Spallation Neutron Source Rapid Cycling Synchrotron (CSNS/RCS) since 2012. In order to evaluate the magnet qualities, a dedicated magnetic measurement system has been developed. The main quadrupole magnets have been excited with DC current biased 25Hz repetition rate. The measurement of magnetic field was mainly based on integral field and harmonics measurements at both static and dynamic conditions. This paper describes the magnet design, the field measurement system and presents the results of the quadrupole magnet. INTRODUCTION The China Spallation Neutron Source [1] is located in Dongguan city, Guangdong Province, China. The CSNS accelerator mainly consists of an 80Mev an H-Linac accelerator, a 1.6Gev Rapid Cycling Synchrotron (RCS) and two beam transport lines. CSNS linac output energy is chosen as 80 MeV in the first phase. The extraction energy of RCS is 1.6GeV at 25 Hz repetition rate. The CSNS/RCS project will be equipped 24 dipole magnets, 48 quadrupole magnets, 16 sextupole magnets and other corrector magnets. Among the dipole and the quadrupole magnets are excited with a repetition frequency of 25Hz. MAGNET DESIGN According to the size of the magnet aperture, there are four types of the quadrupole magnets. The main design parameters and the specifications of the quadrupole magnets are summarized in Table 1. The field quality of the magnets was required respectively for the higher order harmonics, the linear deviation and the integral field deviation. The simulation environment employed in this study is OPERA-3D/Tosca [2].TOSCA was used for the integral field strength and the higher order harmonic components, It is also used to study the end fringing field and end chamfering of the magnets. The OPERA-3D/ELECTRA is used to the eddy current distribution in the magnet cores, in order to reduce the eddy current heating, some slits are cut in the end poles and end plates. Table 1: Main Design Parameters and Specification Magnet type RCSQA RCSQB RCSQC RCSQD Aperture 206mm 272mm 222mm 253mm Effe. length 410mm 900mm 450mm 620mm Max. gradient 6.6 T/m 5 T/m 6 T/m 6.35T/m Unallowed multipole 5×10 -4 5×10 5×10 5×10 Allowed multipole B6/B2 ,B10/B2 4×10 6×10 4×10 6×10 4×10 6×10 4×10 6×10 Lin. deviation 2% 1.5% 1.5% 1.5% rotating coil measurement device and with different rotating coil. One magnet and the field measurement system are shown in Figure 1. The measurement system can be measured at both DC current and DC biased 25Hz AC exciting current. Figure 1: Quadrupole and Setup of the Rotating Coil Data Acquisition Device Figure 2 shows the schematic layout of the magnetic field measurement system. It is commonly available based on National Instruments industrial standard. The signal acquisition card PXI-4462 is selected and provided with a wide dynamic range. The maximum sampling frequency is 204.8 KHz. A high precision motor control ___________________________________________
China Spallation Neutron Source: Design, R&D, and outlook
The China Spallation Neutron Source (CSNS) is an accelerator based multidiscipline user facility planned to be constructed in Dongguan, Guangdong, China. The CSNS complex consists of an negative hydrogen linear accelerator, a rapid cycling proton synchrotron accelerating the beam to 1.6 GeV energy, a solid tungsten target station, and instruments for spallation neutron applications. The facility operates at 25 Hz repetition rate with an initial design beam power of 120 kW and is upgradeable to 500 kW. The primary challenge is to build a robust and reliable user's facility with upgrade potential at a fraction of "world standard" cost. We report the status, design, R&D, and upgrade outlook including applications using spallation neutron, muon, fast neutron, and proton, as well as related programs including medical therapy and accelerator-driven sub-critical reactor (ADS) programs for nuclear waste transmutation. (C) 2008 Elsevier B.V. All rights reserved.