| 摘要 |
<p>A pumping apparatus for evacuating a reactant from a reactive region includes a vacuum able chamber, a hearth for supporting a workpiece, one or more gas introduction valves, one or more exhaust evacuation valves, and an adjustable valve providing one or more pathways there through formed by alignment of separate components of the valve, the components perforated with two or more openings to form the pathways.</p> |
