INDUSTRY COMPONENT

Cathode

A cathode is the electron-emitting electrode in an electron gun, essential for generating electron beams in vacuum tube devices.

Component Specifications

Definition
In industrial electron guns, the cathode is a thermionic or field emission component that emits electrons when heated or subjected to an electric field. It serves as the negative electrode where electron flow originates, typically made from materials with low work functions to facilitate efficient electron emission under high vacuum conditions.
Working Principle
Operates on thermionic emission (heated cathode) or field emission (cold cathode) principles. When sufficient thermal energy or electric field is applied, electrons overcome the material's work function barrier and are emitted into the vacuum, forming a controlled electron beam accelerated toward the anode.
Materials
Tungsten, thoriated tungsten, lanthanum hexaboride (LaB6), or oxide-coated nickel alloys. High-purity materials with melting points above 2000°C for thermionic cathodes; carbon nanotubes or sharp metal tips for field emission cathodes.
Technical Parameters
  • Lifetime 1000-10000 hours
  • Work Function 2.0-4.5 eV
  • Emission Current 0.1-1000 mA
  • Vacuum Requirement <10^-6 mbar
  • Operating Temperature 1500-2800 K (thermionic)
Standards
ISO 17560, DIN 54115

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Cathode.

Parent Products

This component is used in the following industrial products

Engineering Analysis

Risks & Mitigation
  • Thermal degradation
  • Emitter poisoning from residual gases
  • Arc discharge in poor vacuum
  • Work function increase over time
FMEA Triads
Trigger: Contamination from oil backstreaming or outgassing
Failure: Reduced emission current, unstable beam
Mitigation: Implement strict vacuum protocols, use getters, and perform regular cathode conditioning
Trigger: Overheating due to insufficient cooling or excessive current
Failure: Cathode deformation or material evaporation
Mitigation: Install temperature monitoring, use pulse operation for high currents, and ensure proper heat sinking

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
±5% emission current stability, ±0.1 mm dimensional accuracy
Test Method
Emission characteristic testing per ISO 17560, vacuum bake-out at 250°C for 24 hours

Buyer Feedback

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Frequently Asked Questions

What is the difference between thermionic and field emission cathodes?

Thermionic cathodes require heating to emit electrons, offering stable high currents but limited lifespan. Field emission cathodes use strong electric fields for cold emission, providing higher brightness and longer life but requiring ultra-high vacuum.

How does cathode material affect electron gun performance?

Material determines work function, emission efficiency, and operational stability. Low work function materials like LaB6 reduce energy consumption, while refractory metals like tungsten withstand higher temperatures but require more power.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

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