Pumped TEM Instruments

The first instruments applying differentially pumped vacuum columns were mainly used for low-magnification imaging and electron diffraction investigations 

The construction materials of all the heated parts of the holder are of utmost importance, as not all materials remain stable when exposed to gas atmospheres of varying composition at elevated temperatures. For example, the tungsten heating element breaks when used in oxidizing gases, and heaters constructed from other materials (e.g., steel) and with different thermal connections to the cup must be applied instead. Moreover, it is also important to choose the materials for construction and for the holder design so that drift of the cup (and drift of the sample) is minimized when the temperature of the holder is changed. 

Photo of tip of a sample holder for heating the catalyst specimen during exposure to reactive gases. The holder body suspends a cup with the TEM specimen grid. The cup is thermally and electrically isolated from the holder body and can be heated by a tungsten filament located inside the cup. The temperature is measured by a thermocouple mounted on the outside of the cup. 

The first instruments applying differentially pumped vacuum columns were 

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The fourth layer consists of a safety instrumented system (SIS) and/or an emergency shutdown (ESD) 5 y5 -tem. The SIS, formerly referred to as a safety interlock system, automatically takes corrective action when the process and BPCS layers are unable to handle an emergency. For example, the SIS could automatically turn off the reactant and catalyst pumps for a chemical reactor after a high temperature alarm occurs. The SIS is described in Section 10.1.4. 

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