Vacuum systems Temperature approach

Pressure/vacuum, 435, 466 Vacuum systems, 343 Absolute pressure conversions, 363 Air inleakage, 366 Calculations, 366-375 Dissolved gases release, 368 Estimated air inleakage, table, 366 Evacuation time, 371 Maximum air leakage, chart, 367 Specific air inleakage rates, 368 Temperature approach, 375 Classifications, 343 Diagrams, 380 Pressure drop, 353 Pressure levels, 343, 352 Pressure terminology, 348 Pump down example, 381 Pump down time, 380 Thermal efficiency, 384 Valve codes, 26... 

For column pressure control there are Ihrea genaial approaches vent bleed (to arraosphere or to vacuum system), hot vapor bypass, and flooded condenser. These approaches are illustrated in Fig. 5.11-2.3 For an atmospheric column, the vent approach is quite simple. The vapor bypass represents a temperature bleading method. Partial flooding of the condenser suiface adjusts the bent transfer capability or the condenser. The schemes are generally self-explanatory. 

The possibility of producing a system of positronium atoms at a sufficiently high density and low temperature to produce Bose-Einstein (BE) condensation has been raised by Liang and Dermer (1988) and Platzman and Mills (1994). The former authors outlined a scheme in which positronium atoms are laser-cooled in vacuum, which seems feasible despite their short lifetimes because of their low mass. The required temperature of the positronium is around 0.1 K and the density is 1015 cm-3. Liang and Dermer (1988) argued that the overall scheme appears possible, but hitherto neither the temperature nor the density condition has been approached and laser cooling of positronium has not yet been attempted. 

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