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the sample under different conditions.
2.4.
Vacuum system
The electron optical lens barrel and the sample chamber must be operated
under a certain vacuum state, and the realization and control of the entire
system vacuum is completed by the vacuum system. The vacuum system is
mounted below the sample chamber and is connected directly to the barrel via
a vacuum line.
The vacuum system is shown in Figure 2 2. It mainly includes ion pump,
molecular pump, mechanical pump, connecting pipe, damping device, various
valves, and various measurement regulations. The details are as follows:
1.
Ion pump: used for pumping system ultra-high vacuum.
2.
Molecular pump: used to pump high vacuum system.
3.
Mechanical pump: used for pumping system low vacuum and molecular
pump pre-stage vacuum.
4.
Connecting the pipe: for the connection between the vacuum parts.
5.
Various valves: for vacuum control, for example: V1 can separate the
electron gun from the sample chamber. When the sample chamber is
deflated, the electron gun can maintain the vacuum state; V2 is used to
pump the sample chamber and the electron gun is low vacuum; when the
sample chamber When the electron gun reaches the molecular pump start-
up requirement, the molecular pump starts to make the system obtain a
high vacuum; when the sample chamber and the electron gun reach the ion
pump start-up requirement, the ion pump starts, so that the system obtains
an ultra-high vacuum.
6.
Vacuum measurement regulation: vacuum measurement in real time,
vacuum control with valve.
7.
Air compressor: The air compressor supplies power to each pneumatic
valve.
