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 ___________________________________________
The unfolded universe of elementary particles. A geometric explanation of the standard model structure
We propose a geometric explanation of the standard model of Glashow, Weinberg and Salam for the known elementary particles. Our model is a generic Quantum Field Theory in dimension four, obtained by developing along a Lorentz sub-manifold the lagrangian of Einstein and Dirac in dimension twelve. The main mechanism which gives birth to the standard model is a certain gauge fixing of triality, which permits to identify the multiplicity of fermions, as seen from the four dimensional world, with the eight unseen dimensions of the generating universe. In this way we get the known tables of particles, explaining the series of fermions and the gauge bosons. We suggest that the Higgs field dynamics could appear through a bosonization of the right handed neutrino and correspond to a displacement in the unseen dimensions. We also propose hypotheses for dark matter, and perhaps dark energy. Then we suggest predictions to go beyond the standard model.