| 摘要 |
A cryogenic vacuum pump has an expander module (12) suspended from the vacuum chamber of an electron microscope by a metal bellows (32) which dampens the vibrations transmitted to the electron microscope from the expander module. A weight (44) mounted on the expander module and disposed around the bellows counters the lifting force of the atmospheric pressure acting on the expander module and protects the bellows. The expander module is maintained in a centered position by vibration damping isolators (50) disposed symtrically around the expander module and which are attached to a support (10) extending down from the vacuum housing. In one embodiment the isolators are bar magnets which repel magnetic ring attached to the expander module. In another embodiment the isolators are ladders in which the rungs are wire cables tensioned between a side members attached respectively to the expander module and to the support. The compressor (16) of the cryogenic vacuum pump is a separate unit having a high pressure feed line (14) and a low pressure return line (16) which are connected to the inlet and outlet of the expander module by helical flexible hoses having freely suspended turns which damp the vibrations transmitted by the hoses. |
