What does the cathode assembly contain?

What does the cathode assembly contain?

• A. Focusing Cup + Tungsten Tube
• B. Filament Only
• C. Copper Shield
• D. Vacuum Envelope

Answer: (A)

The cathode assembly is where electrons are created and directed toward the anode. It includes the tungsten filament, which is heated to emit electrons via thermionic emission, and the focusing cup, a negatively charged concave cup that shapes and focuses those electrons into a tight beam. The copper shield and vacuum envelope are parts of the tube as a whole, but they are not the components that make up the cathode assembly. So the combination of the focusing cup with the tungsten filament best describes what sits in the cathode assembly.

The cathode assembly is where electrons are created and directed toward the anode. It includes the tungsten filament, which is heated to emit electrons via thermionic emission, and the focusing cup, a negatively charged concave cup that shapes and focuses those electrons into a tight beam. The copper shield and vacuum envelope are parts of the tube as a whole, but they are not the components that make up the cathode assembly. So the combination of the focusing cup with the tungsten filament best describes what sits in the cathode assembly.