Electron microscopy
 
Vacuum at EM Stages
- Practical Electron Microscopy and Database -
- An Online Book -
Microanalysis | EM Book                                                                                   http://www.globalsino.com/EM/        

This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
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Ion pumps are often directly added to the specimen stage (especially for analytical EMs) or gun chambers of EMs to enhance the vacuum in these important regions.

As shown in Figure 3188 (a), in most modern TEMs, the electron gun, top lenses, and specimen chamber are maintained at ultra-high vacuum by an ion pump, while the viewing screens and photographic chamber are maintained at a lower vacuum, which is referred to as high vacuum, by either a diffusion pump or a turbomolecular pump. This vacuum level is backed by a mechanical (rotary) pump. However, some TEMs have lower vacuum in the specimen chamber as shown in Figure 3188 (b).

Vacuum in TEMs: (a) Modern TEMs, and (b) Some TEMs.

Figure 3188. Vacuum in TEMs: (a) Modern TEMs, and (b) Some TEMs.

 

 

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