Conical Liquid-Metal Beam Target for Expanded Irradiation Area

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Solution Overview

Problem

Existing beam target systems face inefficiencies in disposing irradiation targets for nuclear reaction products and limited space for using generated nuclear reaction products, particularly when using liquid metal films inclined to increase irradiation area.

Innovation Solution

A beam target system with a cone body having a tapered inner surface and supply means to form a helical liquid metal film, allowing efficient use of generated nuclear reaction products by increasing the irradiation area while maintaining a short length and preventing boiling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the liquid film is inclined to increase irradiation area, then the irradiation area is improved, but the space for disposing irradiation target objects is limited

Engineering Contradiction:
Improveirradiation areaVSAvoidspace for irradiation target objects
Core Design Contradiction:
Area of stationary objectVSAdaptability or versatility

Solution Approach 1:

The patent transitions from a two-dimensional inclined plane to a three-dimensional conical structure. The liquid metal flows along the conical inner surface, creating a conical liquid film that expands in the radial direction while maintaining a compact axial length. This dimensional change allows the irradiation area to be increased without compromising the space available for disposing irradiation target objects, as the conical geometry provides radial expansion rather than requiring extended inclination space.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent employs a conical surface instead of a flat inclined plane. The conical geometry with its curved surface allows the liquid metal to flow in a helical path, creating a conical liquid film that maximizes the irradiation area within a compact volume. The curved surface area of the cone provides a larger irradiation area compared to a flat plane of the same base radius, while maintaining the ability to dispose target objects in the surrounding space.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Productivity

If the beam intensity is increased to generate more nuclear reaction products, then the productivity is improved, but the thermal load on the beam target becomes problematic

Engineering Contradiction:
Improvenuclear reaction product generationVSAvoidthermal load
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The patent implements a continuous circulation system where liquid metal is continuously supplied to the conical target, irradiated, and then circulated back through a heat exchanger for cooling. This continuous action ensures that the liquid metal is constantly refreshed and cooled, preventing thermal accumulation while maintaining high beam intensity for maximum nuclear reaction product generation. The continuous flow prevents localized heating and maintains optimal thermal conditions throughout the process.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent uses liquid metal flow dynamics to manage thermal load. The liquid metal circulates through the conical target, absorbing heat from the beam irradiation, and is then cooled in a heat exchanger before being recirculated. This hydraulic circulation system efficiently transports heat away from the irradiation zone, enabling high beam intensity operation without excessive thermal accumulation. The liquid metal acts as both the target material and the cooling medium.

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Reliability

If a solid beam window is used to contain the liquid metal, then the containment is improved, but the beam window is damaged due to thermal and mechanical stress

Engineering Contradiction:
Improveliquid metal containmentVSAvoidbeam window durability
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent removes the solid beam window from the system entirely. Instead of containing the liquid metal with a solid barrier, the invention uses a magnetic field to confine the liquid metal in a windowless configuration. This extraction of the beam window eliminates the source of damage while maintaining effective containment of the liquid metal target, allowing high-intensity beam irradiation without compromising either containment or structural integrity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical containment system (solid beam window) with a magnetic field-based containment system. The liquid metal, being conductive, is confined by magnetic fields generated by coil assemblies surrounding the conical target. This substitution eliminates the mechanical stress and thermal damage problems associated with solid windows while providing reliable containment. The magnetic field confinement allows the liquid metal to be held in place without physical barriers that would otherwise fail under thermal and mechanical load.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 system enables efficient use of nuclear reaction products by increasing the irradiation area and allowing disposal of targets around the cone body, while preventing boiling through centrifugal force, thus enhancing the use efficiency of generated neutrons.

Implementation Method 1

A flow path of the liquid metal is curved, and hence the pressure of the liquid is increased by centrifugal force

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

A beam target system is used for irradiating metal or the like serving as a target with a high-intensity charged particle beam to generate a neutron

Methodology Applied
Scientific EffectNuclear reaction: Nuclear Fusion

Implementation Method 3

the cone body has a tapered inner surface which is reduced in diameter toward a tip

Methodology Applied
Scientific EffectGeometry: Geometry

Data Source

PatentEP3933856B1Beam target and beam target system
Publication Date: 2025.09.17 RIKEN CO LTD
  • EP3933856B1 patent drawingFigure 1
  • EP3933856B1 patent drawingFigure 2A~2C
  • EP3933856B1 patent drawingFigure 3

AI summary

A beam target for generating a nuclear reaction product by irradiation with a beam obtained from a beam generation source includes a cone body which has a tapered inner surface which is reduced in diameter toward a tip, and supply means for supplying liquid metal to the inner surface of the cone body to form a liquid film of the liquid metal on the inner surface. It is possible to form the liquid film of the liquid metal on a cone body surface to increase an irradiation area of the beam, and also dispose a target substance such as LLFP around the cone body, and hence it is possible to efficiently use the nuclear reaction product (e.g., a neutron) generated by beam irradiation of the liquid metal.