Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix
| Anti-Contamination Device (ACD) is a “cold trap” or “cold finger” (in Figure 4211a) for improving vacuum around the sample. Liquid nitrogen (liquid N2, also called LN2) is added to the decontaminator device (trap), which cools metal plates located just above or below the specimen and between the upper and lower pole pieces in TEM (see Figure 4211b), resulting in condensation of water and organic vapors and providing a low partial pressure of these components in the immediate vicinity of the TEM specimen. The liquid N2 dewar is visible on the side of the TEM column. The anti-contamination fin installed in the specimen chamber is also considered to be a kind of cryo-pumps.
Figure 4211a. Anti-Contamination Device (ACD) on a JEOL TEM system.
Figure 4211b. (a) Schematic side-view and (b) Schematic top-view of the relative position of ACD fin in a TEM column.
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