Anode (Extraction Electrode): Current Capacity 0.1-100 mA

Component Specifications

Definition

The Anode (Extraction Electrode) is a positively charged electrode in electron gun systems that creates an electric field to extract electrons emitted from the cathode. It functions as the first acceleration stage, pulling electrons into the vacuum chamber and initiating their trajectory toward subsequent focusing and deflection components. This electrode typically operates at high positive voltages (ranging from 1kV to 30kV depending on application) and must maintain precise geometric alignment to ensure proper electron beam formation.

Working Principle

The anode operates on electrostatic principles: when a high positive voltage is applied relative to the cathode, it creates a strong electric field that overcomes the work function of the cathode material, extracting electrons via field emission or thermionic emission. The extracted electrons are then accelerated toward the anode aperture, passing through it to enter the main acceleration region of the electron gun.

Materials

High-purity molybdenum (Mo), tungsten (W), or copper (Cu) with oxygen-free high conductivity (OFHC) properties; sometimes coated with refractory materials like tantalum (Ta) or graphite for enhanced thermal stability and reduced secondary electron emission.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Surface Finish	Ra ≤ 0.4 μm
Voltage Rating	1-30 kV
Current Capacity	0.1-100 mA
Aperture Diameter	0.5-5.0 mm
Vacuum Compatibility	≤ 10^-6 Torr
Operating Temperature	Up to 1500°C

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 14644-1, DIN 25424, ASTM E1256

Parent Products

This component is used in the following industrial products

Electron Gun

A device that generates, accelerates, and focuses a beam of electrons for medical radiation therapy applications.

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Engineering Analysis

Risks & Mitigation

Electrical arcing due to contamination
Thermal deformation at high currents
Secondary electron emission causing beam instability
Material degradation from electron bombardment

FMEA Triads

Trigger: Surface contamination from hydrocarbons or particulates
Failure: Electrical breakdown and arcing between electrodes
Mitigation: Implement strict cleanroom assembly procedures and regular high-vacuum baking

Trigger: Excessive electron beam current density
Failure: Localized overheating and material deformation
Mitigation: Incorporate active cooling systems and current limiting circuits

Trigger: Improper alignment with cathode
Failure: Asymmetric electron extraction and beam deflection
Mitigation: Use precision alignment fixtures and laser alignment verification

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±0.01 mm for aperture diameter, ±0.05 mm for positional alignment

Test Method

High-voltage breakdown testing per ASTM D149, electron beam profiling using Faraday cups, thermal cycling under operating vacuum

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

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Inspection readiness

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Manufacturers of Anode (Extraction Electrode)

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Frequently Asked Questions

What is the primary function of the anode in an electron gun?

The anode serves as the extraction electrode that creates the electric field needed to pull electrons from the cathode and initiate their acceleration toward the target.

Why are refractory metals commonly used for anode construction?

Refractory metals like molybdenum and tungsten offer high melting points, excellent thermal stability, and low vapor pressure under high vacuum conditions, making them ideal for high-temperature electron emission environments.

How does anode geometry affect electron beam quality?

The aperture size, shape, and positioning relative to the cathode directly influence beam focus, current density, and trajectory stability. Precise machining and alignment are critical for optimal performance.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Anode (Extraction Electrode)