Electron Gun

Question 1

The electron gun generates _________________.

Answer 1

The electron gun generates a stable beam of electrons of adjustable energy

Question 2

4 major causes of premature filament failure?

Answer 2

Answer

1. Oversaturation
2. High voltage discharge caused by dirt in the gun region
3. Poor vacuum
4. Air leaks or outgassing of/from contaminants in the gun chamber

Question 3

What is the Schottky-emission effect?

Answer 3

Field enhanced thermionic emission–high electric field is applied to heated metal filament

Question 4

What are the 3 types of electron guns according to their method of emission?
Which one is found in our SEM?

Answer 4

1.Field Emission (FE) Electron Gun
2.Schottky-Emission Electron Gun
3.Thermionic Emission Electron Gun
Zeiss Supra 40VP has a Schottky-emission electron gun