Che-Kai Chan

Integration Design and Installation of Girder Systems in the Injection Section of Taiwan Photon Source

The electron beam is injected from the end of the transport line into the injection section of the storage ring in Taiwan Photon Source (TPS). A girder system for the injection section has been designed to support AC/DC septum magnets, four kicker magnets (K1–K4), and vacuum chambers. The girder system includes three girders, a Rapson-slide mechanism, and stages for the septum/kicker magnets. To improve the reliability and the stability of the injected electron beam, the girder systems are designed and installed in the injection section of TPS, as described in this chapter. The positioning accuracy of installing three girders and the stages for septum/kicker magnet are, respectively, within 0.3 and 0.05 mm.

Fluid Flow Inside a Rectangular Duct With Two Opposite Walls Roughened by Deepened Scales

Laser-Doppler velocimetry (LDV) measurements supplemented by numerical simulation and flow visualization were performed to study flow characteristics and explain the reported heat transfer features in a rectangular channel with two opposite walls roughened by deepened scales. The study is lacking in the published literature. Ratios of scale print diameter to channel height, scale maximum depth to channel height and scale pitch to scale maximum depth were 1.0, −0.1, and 10 respectively. The scale-roughened section had a cross-sectional width to height ratio of 8. All measurements were undertaken at a fixed Reynolds number, based on hydraulic diameter and cross-sectional bulk mean velocity, of 10000 with air flows directed forward and downward. Results are documented in terms of distributions of mean velocity components, mean velocity vector field, fluctuation components, and turbulent kinetic energy. The distances attaining periodic fully developed flow condition are identified. Both LDV measurements and laser-sheet flow visualization unravel the presence of near-wall secondary vortex arrays in the cross-sectional planes. The fluid flow results are subsequently used to explain previously published heat transfer trends. The dominant flow dynamic factors are recognized to provide the logic for the differences in heat transfer enhancements attained by the forward and downward channel flows over the scaled walls. A comparison of the computed sizes of cavity trapped vortex illustrates the reported difference in heat transfer augmented by the scale and dimple roughened surfaces as well as by the turbulent and laminar flows.© 2009 ASME

Comparative study of Ar-implanted Ti-Zr-V non-evaporable getter films on the Al-alloy substrate

Original and Ar-implanted Ti-Zr-V non-evaporable getter (NEG) films were characterized using scanning electron microscope, X-ray diffractometer, electron spectroscopy for chemical analysis, and transmission electron microscopy. Similar properties and results were observed in the surface morphology, the composition, and the crystalline structure for original and implanted Ti-Zr-V films. However, the thermal activation temperature were increased for implanted films. The analysis of implanted Ti-Zr-V films revealed that defects formed in the upper layers of the films can trap diffused gaseous atoms from the surface into the Ti-Zr-V films. Therefore, the thermal activation reaction of Ti-Zr-V films would be affected due to implantation-induced defects in the films. We show directly that the thermal activation reaction of Ti-Zr-V films are changed by the existence of defects in the getter films.Original and Ar-implanted Ti-Zr-V non-evaporable getter (NEG) films were characterized using scanning electron microscope, X-ray diffractometer, electron spectroscopy for chemical analysis, and transmission electron microscopy. Similar properties and results were observed in the surface morphology, the composition, and the crystalline structure for original and implanted Ti-Zr-V films. However, the thermal activation temperature were increased for implanted films. The analysis of implanted Ti-Zr-V films revealed that defects formed in the upper layers of the films can trap diffused gaseous atoms from the surface into the Ti-Zr-V films. Therefore, the thermal activation reaction of Ti-Zr-V films would be affected due to implantation-induced defects in the films. We show directly that the thermal activation reaction of Ti-Zr-V films are changed by the existence of defects in the getter films.

Measurement of the Pressure in the TPS Booster Ring

The booster ring of Taiwan Photon Source (TPS) is designed to provide full energy injection 3 GeV ramped up from 150 MeV with a small beam emittance. It is a synchrotron accelerator of circumference 496.8 m. The vacuum chamber through the magnets is made of thin stainless-steel tube extruded to an elliptical cross section of inner diameters 35 mm and 20 mm, and thickness 0.7 mm. The other chambers have standard 35CF round tube. The vacuum system was baked in the first installation. Because the residual stress of the stainless-steel elliptical tubing caused the magnetic field to become unstable, all elliptical tubing was removed for annealing to proceed, and reinstalled without baking. The ultimate pressure and data for the residual gas are shown as follows.