| 摘要 |
<p>An exhaust port form a cryopump vacuum vessel (12) leads to an exhaust valve (60). The valve (60) is protected from contamination by a filter stand pipe (62) which extends from the exhaust port into the vacuum vessel (12) and which is open at its end (64) opposite to the exhaust port. The stand pipe (62) is of porous material which allows the free flow of gas, water, and liquid cryogens therethrough while retaining contaminating debris within the vacuum vessel (12). The filter conduit (62) is of screen formed into a cylinder. One end (70) is tapered and pressed into the exhaust conduit (58). The screen cylinder is stopped in the exhaust conduit by a circumferential ridge (72).</p> |
