High-Performance Cold Cathode X-ray Tubes Using a Carbon Nanotube Field Electron Emitter

Area of Science:

• Materials Science
• Physics
• Engineering

Background:

• Traditional X-ray tubes often face limitations in current density and focal spot size.
• Carbon nanotubes (CNTs) offer unique field emission properties beneficial for electron source development.

Purpose of the Study:

• To fabricate and characterize a cold cathode X-ray tube using a free-standing carbon nanotube (CNT) film as the field electron emitter.
• To evaluate the performance metrics including current density, electron beam transmittance, focal spot size, and operational lifetime.

Main Methods:

• Fabrication of a cold cathode X-ray tube with a free-standing CNT film emitter.
• Characterization of the CNT film, comprising vertically aligned CNT bundles at the edge.
• Measurement of tube current density, electron beam transmittance, focal spot size (FSS), and lifetime.

Main Results:

• Achieved an extremely high tube current density of 152 A/cm² (106.4 mA).
• Demonstrated high electron beam transmittance (95.2%) and a small focal spot size (0.5 mm).
• Exhibited stable operational lifetime over 100,000 shots.

Conclusions:

• The high performance is attributed to numerous emission sites on the CNT film edge and optimized focusing lens.
• The developed CNT cold cathode X-ray tube shows significant potential for diverse X-ray applications.
• Future applications include advanced medical diagnosis and security screening systems.