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The VP-vacuum system for ULTRA |
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| | The specimen chamber and the GEMINI® column are divided into four pressure regions separated by pressure limiting apertures.
The vacuum in the field emitter area and the upper part of the GEMINI® column is maintained by two ion getter pumps, the lower part of the column is pumped by a turbomolecular pump (TMP). The specimen chamber can be separated from the TMP vacuum by a chamber isolation valve.
As soon as VP mode is selected the system automatically regulates the chamber pressure and additionally selects the variable pressure detector for you. An automatic feed back loop ensures that the new pressure is accurately set and regulated in the specimen chamber. With a single mouse click high vacuum can be selected if required. |