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Glossary terms about Column

Column
The component of an electron microscope that houses the electron gun, electromagnetic lenses, and accessory equipment.


14 pages mention Column

Detectors
 
Electromagnetic lenses, apertures and beam size
Under the influence of a magnetic field, electrons assume a helical path, spiralling down the column
Electron column
 
Electron gun
Thermoelectrons produced by the filament are accelerated through the application of a voltage between the filament and the anode, thus creating an electron beam that streams down the microscope column
Focused ion beam (FIB) technology
Machines can have both ion and electron columns on a single instrument (called dual beam instruments). 
High vacuum mode and pump system
 
History
Today, many SEMs are commercially available and they all contain the same essential features: an electron optical column in which an electron beam is generated under high vacuum, and focussed to a tiny spot on the specimen surface. 
Main control panel
Used to indicate that the progress of bringing the specimen chamber and column to atmospheric pressure (lamp is blinking) and when venting is complete (lamp lights up). 
Principles of SEM operation
A scanning electron microscope is a machine comprised of an electron generating component called the gun, a column through which the electron beam travels, a series of lenses to shape the electron beam, the sample chamber at the base, and a series of pumps to keep the system under vacuum. 
Role of sample height
Sample height, or working distance (WD), refers to the distance between the bottom of the SEM column and the top of the sample. 
Specimen chamber
A fail safe circuit controls the vacuum sequence and maintains the appropriate vacuum (~10-6 torr) in the optical column and specimen chamber. 
The electron gun
The hole in the anode allows a fraction of the electrons to continue down the column through the lenses to produce a smaller, more cohesive beam. 
What is an SEM (Parts of the machine)?
the computer that drives the microscope, with the additional bench controls ancillary equipment that, for example, analyses composition. 
What is astigmatism?
This comprises electromagnetic coils placed around in the microscope column in quadruple, sextuple or octagonal orientations.