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.
Status of CSNS Project
The China Spallation Neutron Source (CSNS) accelerator is designed to accelerate proton beam pulses to 1.6 GeV at 25 Hz repetition rate, striking a solid metal target to produce spallation neutrons. The accelerator provides a beam power of 100 kW on the target in the first phase and then 500 kW in the second phase by increasing the average beam intensity 5 times while raising the linac output energy. The project construction has been formally launched in 2011 and it is planned to complete the project in March 2018. It is one of the high intensity proton accelerator projects in the world and it imposes a great challenge to Chinese accelerator community. This presentation will cover the status and challenges of the CSNS project.
Shape and surface texture of molten droplets deposited on cold surfaces
When a molten droplet impacts on a cold surface, the interaction between solidification and fluid dynamics can lead to different shapes and surface textures of deposited droplets. This article presents an experimental study on deposition of small droplets (39 μm diameter) of molten wax ink on solid surfaces. Our results show that both the final shape and the surface texture of deposited droplets are extremely sensitive to deposition conditions, which include initial temperature of droplets, type of substrate surface and distance between substrate and printhead. Different surface textures are observed and shown to depend on the thermal and flow histories of ink droplets during the process of impact. A test using crystalline wax reveals crystallization as one of the major factors in determining the final texture.