DIY Scanning Electron Microscope - Electron Gun Detail

TL;DR

This content explains the construction and operation of the electron gun in a scanning electron microscope.

Transcript

hey guys it is Saturday morning I've got my cup of coffee and I want to talk particle physics so let's head over to the bench and I'll show you what's going on with the electron gun in my scanning electron microscope project so here is a schematic of the electron gun in the electron microscope and I will run through the parts of it and how it's bui... Read More

Key Insights

• 🥶 The electron gun in an electron microscope consists of a filament, when old cylinder, and anode.
• 😥 Voltages in the electron gun system are measured relative to a ground point.
• ⚡ The emission of electrons is controlled by adjusting the voltage on the filament.

Questions & Answers

Q: How is the electron gun in an electron microscope constructed?

The electron gun consists of a filament, when old cylinder, and anode. The filament is heated by a DC power supply, and the when old is a metal plate with a hole. The anode is a plate or cylinder with a hole as well.

Q: What are the voltages involved in the electron gun?

The filament is heated by a DC power supply, the when old is at a lower voltage, and the anode is at a higher voltage. The exact values may vary, but typically the anode is around +5 kV and the when old is around -5 kV.

Q: How are voltages measured in the electron gun system?

Voltages are measured relative to a known ground point, which can be the earth or any other reference point. In this case, the anode is usually chosen as the ground, and other voltages are measured relative to it.

Q: How does the electron gun control the emission of electrons?

The voltage difference between the filament and the when old is controlled by a bias resistor. Adjusting this resistor controls the voltage on the filament, which in turn affects the emission of electrons.

Summary & Key Takeaways

• The electron gun in an electron microscope consists of a filament, when old cylinder (grid), and anode.

• The filament is heated by a DC power supply, and the anode is connected to a high voltage supply.

• The voltage difference between the filament and the when old controls the emission of electrons.