| 摘要 |
<p>An electron beam system comprises a vacuum enclosure (10), a source of electrons (3) within the enclosure, and a passive pump (8) located within or in communication with the enclosure for pumping gases from the enclosure. A supplemental active pump (19) is coupled to the vacuum enclosure and functions simultaneously with the passive pump for pumping from the enclosure gases not removed, or not removed efficiently, therefrom by the passive pump.</p> |
