The Alpha Magnetic Spectrometer AMS-2, planned for a five years mission as attached payload on the International Space Station ISS, is an international experiment searching for anti-matter, dark matter, and missing matter. AMS-2, an improved version of AMS-1 flown on STS 91, consists of various particle detector systems, one of these being the (Silicon) Tracker. The trade-off based choice and the experimental feasibility demonstration of a mechanically pumped two-phase CO 2 cooling loop for the Tracker is discussed in detail. Ongoing and planned development activities are indicated.
The Alpha Magnetic Spectrometer AMS-2 is planned for a five years mission as attached payload on ISS, the International Space Station. It is an international experiment searching for anti-matter, dark matter, and missing matter. AMS-2, an improved version of AMS-1 flown on STS 91, consists of various particle detector systems, one of these being the (Silicon) Tracker. The trade-off based choice and the experimental feasibility demonstration of a mechanically pumped two-phase CO 2 cooling loop for the Tracker is discussed in detail. The current status and ongoing and planned development activities are discussed.
This paper discusses the thermal modeling activities as a design and development tool for the Tracker Thermal Control System, the mechanically pumped, carbon dioxide thermal management system for the AMS-2 Silicon Tracker. Main modeling topics are: radiator sizing and condenser development, set-point control and pre-heating issues with respect to the spatial and temporal temperature gradient requirements of the Tracker.
Following up ideas put forward by J.M. Ottino and colleagues, the possibility of designing a computational tool to optimize the mixing of viscous fluids in industrial devices is studied. It is shown that an efficient method to characterize and quantify a mixing process is to apply the statistical measures introduced by Danckwerts (e.g., intensity of segregation and scale of segregation) on the coarse-grained density distribution of points in Poincaré sections and advection patterns, that can be obtained by tracking the positions of marked fluid elements numerically. This method is not computationally excessively costly and, as is demonstrated here, can be applied easily to experimental dye advection studies. The model system used is the Stokes flow in a two-dimensional cavity transfer mixer: two rectangular cavities which are periodically driven by a solid wall and by the passage of the cavities over each other. This system shares with many industrial devices the complexity that the geometry of the flow is time-dependent. These changes in the geometry of the flow impose difficulties on the techniques of calculating the fluid velocity field (a boundary element method) and the advection of marked fluid elements. Ways of overcoming these difficulties are described.
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