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Direct simulation Monte Carlo method for molecular and transitional flow regimes in vacuum components with static and moving surfacesIn this article we describe an unsteady tube flow model which accounts for the effect of contracted flow around the entrance orifice of the tube which was developed with the aim of preventing vacuum hazards at scientific experimental facilities. Setting an atmospheric pressure drop between the outside and inside of the vacuum tube makes the model applicable to high vacuum, although the model is based on continuous fluid dynamics. We installed an orifice on the inlet end of the tube in the model, and investigated the orifice aperture effect on the propagation velocity of pressure waves.

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We have studied a new and reliable cooling method for diamond crystals in third generation light sources. In order to reduce the strain from brazing between the diamond monochromator and its Cu block cooling device, another diamond platelet was introduced as an interface. Using a finite element method program based on numerical thermal analysis, the mounting strain was estimated at 0.6 arcsec. Then data was confirmed through preliminary x-ray characterization using laboratory x-ray sources. The strain in the area exposed to a 1 mm×4 mm synchrotron radiation beam (absorbed power 100 W) was estimated by simulation at an acceptable 1.0 arcsec. Applying the new cooling method, the diamond crystal can tolerate synchrotron radiation power up to 100 W.