Triode Hollow Cathode Electron Gun Mitigating Back-Streaming

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Solution Overview

Problem

Conventional triode electron guns used in linear particle accelerators face issues with back-streaming electrons, which cause temperature increases and shorten the lifespan of the cathode and grid, leading to unwanted and uncontrolled electron emission known as 'dark current' due to the deposition of impregnating materials on surfaces within the RF structure.

Innovation Solution

A triode hollow-cathode electron gun design incorporating a hollow cathode, a post, a heating filament, an anode, a control grid, and a shadow grid, with a cylindrical sleeve mechanically coupled to the hollow cathode, helps mitigate back-streaming electrons by providing a well-behaved converging electron beam and preventing unwanted emissions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a conventional triode electron gun is used to supply electron beam current to a linear particle accelerator, then the electron beam current can be controlled and changed quickly, but back-streaming electrons cause temperature rise and shorten the lifespan of the cathode and grid

Engineering Contradiction:

Improveelectron beam current control speedVSAvoidcathode and grid lifespan

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent extracts and removes back-streaming electrons from the system using a magnetic field generated by a solenoid coil. The magnetic field deflects electrons that are moving backward toward the cathode and grid, preventing them from impacting these components and causing temperature rise. This selective removal of harmful electrons extends the lifespan of the cathode and grid while maintaining the fast control capability of the triode electron gun.

Inventive Principle:

Principle #2Taking out (Extraction)

2Productivity

If back-streaming electrons impact the cathode and grid, then the electron beam current can be maintained, but the temperature of the cathode and grid increases causing evaporation of impregnating material

Engineering Contradiction:

Improveelectron beam currentVSAvoidcathode and grid temperature

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent converts the harmful back-streaming electrons into a beneficial effect by using their presence to generate a magnetic field through the solenoid coil. The magnetic field created by the moving electrons interacts with the coil to produce a deflecting force that redirects these electrons away from the cathode and grid. This transforms the harmful thermal impact into a useful magnetic deflection mechanism that protects the components while maintaining electron beam current.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If impregnating material evaporates from the cathode due to temperature rise, then the electron emission can be maintained, but the material deposits on the grid and RF structure causing unwanted electron emission

Engineering Contradiction:

Improveelectron emissionVSAvoidunwanted electron emission or dark current

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a magnetic field as an intermediary between the cathode and the grid/RF structure. This magnetic field acts as a barrier that prevents evaporated impregnating material from traveling along the electron beam path and depositing on the grid and RF structure. By blocking the transport of impregnating material, the magnetic field eliminates the source of unwanted electron emission while allowing the cathode to maintain its electron emission capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution effectively reduces the impact of back-streaming electrons, extending the lifespan of the electron gun and minimizing 'dark current' by maintaining a stable electron beam trajectory and reducing thermal stress on the cathode and grid components.

Implementation Method 1

a hollow cathode 310, a heating filament 330

Methodology Applied

Scientific EffectThermionic emission: Thermionic Emission

Implementation Method 2

an anode 210, a control grid 320

Methodology Applied

Scientific EffectElectric field: Electric Field

Data Source

PatentUS10115556B2Triode hollow cathode electron gun for linear particle accelerators

Publication Date: 2018.10.30 IMG ALTAIR LLC

AI summary

The present invention generally relates to systems and methods for generating controllable beam of electrons using a hollow-cathode triode electron gun that substantially mitigate impact of back-streaming electrons. In one embodiment, a triode hollow-cathode electron gun is configured to provide electrons and substantially mitigates the impact of back-streaming electrons. The triode hollow-cathode electron gun includes a hollow cathode, a heating filament, an anode, a control grid, a shadow grid and a sleeve mechanically coupled to the hollow-cathode. The sleeve is substantially centered on the axis of the triode hollow-cathode electron gun and configured to maintain shape and trajectory of emitted beams of electrons.