Damages destructive vacuum

Water has the unique ability to expand 1570 times when changing from a liquid to a vapor, and to contract 1570 times when it is condensing. To visualize this dramatic contraction, just think that a typical rail tank car filled with steam at atmospheric pressure could condense to the volume of 10 or 11 gallons of water. [1] These properties can result in destructive vacuum damage as just shown. The explosive expansion from water to steam can result in a catastrophic incident as the next case history graphically demonstrates. 

Cavitation Formation of transient voids or vacuum bubbles in a liquid stream passing over a surface is called cavitation. This is often encountered arouna propellers, rudders, and struts and in pumps. When these bubbles collapse on a metal surface, there is a severe impact or explosive effec t that can cause considerable mechanical damage, and corrosion can be greatly accelerated because of the destruction of protective films. Redesign or a more resistant metal is generally required to avoid this problem. 

Typically, PIXE measurements are performed in a vacuum of around 10 Pa, although they can be performed in air with some limitations. Ion currents needed are t5q)ically a few nanoamperes and current is normally not a limiting factor in applying the technique with a particle accelerator. This beam current also normally leads to no signifrcant damage to samples in the process of analysis, offering a non-destructive analytical method sensitive to trace element concentration levels. 

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