Scanning Electron Microscopy
Scanning Electron Microscopy
Scanning Electron Microscopy
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<strong>Electron</strong> Gun<br />
• There are two main types of gun – Thermionic and Field Emission (FEG).<br />
• Thermionic gun :- Simplistically, a material (often a piece of twisted tungsten) is heated<br />
to a high temperature so that it will emit electrons.<br />
• Can also use LaB 6 crystal grown to a tip – gives a brighter beam than W for same kV.<br />
Analytical<br />
Workshop 2012<br />
Tungsten filament Tungsten filament assembly LaB 6 filament tip
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