| 摘要 |
<p>A differentially pumped seal apparatus (14) comprising a rough port nozzle (R), a medium port nozzle (M) and a high port nozzle (H), each with a centrally located sleeve (34,36,40) defining concentric apertures (44,48,52). Each nozzle is configured as a sector of a circular cylinder which provides for large channels (62,72,76) to be formed for connecting the sleeve apertures (44,48,52) of each nozzle directly to vacuum pumps (46,50,54) to thereby provide a graded seal with high conductance and increased pumping efficiencies, higher vacuum and a smaller gap between the sleeve (34,36,40) and a workpiece (12).</p> |
