UHV

UHV could refer to:University of Houston–VictoriaUltra high vacuum
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Ultra high vacuum (UHV) is the regime characterised by pressures lower than about 10−7 pascal or 100 nanopascals (~10−9 torr). UHV requires the use of special materials, extreme cleanliness, and baking the entire system to remove water and other trace gases. See Vacuum for descriptions of other levels of vacuum. Pressure is also measured by a barometer in the weather form of the "air pressure" of geography. At these low pressures, gas molecules rarely run into each other. The mean free path of a gas molecule at 10−7 pascal or 100 nanopascals (~10−9 torr) is approximately 40 km, so gas molecules will collide with the chamber walls many times before colliding with each other. Almost all interactions therefore take place at various surfaces in the chamber.
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