Circular Accelerator Magnetic Field Layout for Beam Extraction Efficiency

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Solution Overview

Problem

The existing circular accelerators suffer from reduced beam extraction efficiency due to beam particles diverging in the vertical direction during extraction, leading to increased beam loss and decreased beam current, which prolongs treatment time in particle beam therapy systems.

Innovation Solution

A circular accelerator design with a magnetic field configuration that includes a first region with a weak magnetic field gradient towards the outer periphery and a second region with a strong magnetic field gradient, positioned downstream of an orbit aggregation region, maintaining a balance between convergence and divergence forces to suppress beam loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a linear accelerator is used for particle beam treatment, then the treatment depth can be adjusted by changing beam energy, but the device requires a large room and has high construction costs

Engineering Contradiction:
Improvedevice sizeVSAvoidtreatment depth adjustment
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The particle beam is divided into multiple bunches that are accelerated at different times and positions around the circular accelerator ring. Each bunch can be independently controlled to deliver radiation at different depths, enabling depth adjustment without changing the overall accelerator size or energy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple particle bunches are nested within the circular accelerator structure, with each bunch following a slightly different trajectory or timing. This allows multiple treatment depths to be achieved within a single compact circular accelerator facility.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Productivity

If multiple linear accelerators are used to treat different body parts simultaneously, then treatment efficiency improves, but the device complexity and space requirements increase

Engineering Contradiction:
Improvetreatment efficiencyVSAvoidnumber of accelerators
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

A single circular accelerator is designed to perform multiple treatment functions simultaneously by accelerating different particle bunches to different energies and directing them to different target locations. This multi-functional approach enables treatment of multiple body parts with one device.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The circular accelerator operates continuously, accelerating particle bunches in an unbroken cycle. Multiple bunches are injected and accelerated simultaneously at different positions around the ring, allowing continuous treatment of multiple targets without interruption or idle time.

Inventive Principle:
Principle #20Continuity of useful action

3Ease of operation

If a circular accelerator with separate injection and extraction points is used, then particle beam control is improved, but the device complexity and number of components increase

Engineering Contradiction:
Improvebeam controlVSAvoidnumber of components
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The injection system and extraction system are merged into a unified magnetic field configuration within the circular accelerator. The same magnetic field structure that guides particles around the ring also performs both injection and extraction functions, reducing the number of separate components.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The magnetic field is configured to create equipotential regions that allow seamless transition between injection and extraction operations. Particles can be injected and extracted at different positions around the ring without requiring additional accelerating structures or complex field adjustments.

Inventive Principle:
Principle #12Equipotentiality

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

This design enhances beam extraction efficiency, allowing for higher beam current and shorter treatment times in particle beam therapy systems by stabilizing beam trajectories, regardless of energy levels.

Implementation Method 1

a particle source for generating charged particles, a first accelerator for accelerating the charged particles generated by the particle source in a radial direction

Methodology Applied
Scientific EffectElectrostatic acceleration: Electrostatic Induction

Implementation Method 2

a first accelerator for accelerating the charged particles generated by the particle source in a radial direction

Methodology Applied
Scientific EffectElectric field acceleration: Electromagnetic Induction

Implementation Method 3

a second accelerator for accelerating the charged particles along an axial direction extending in parallel with the axis of the solenoid magnet

Methodology Applied
Scientific EffectElectric field acceleration: Electromagnetic Induction

Implementation Method 4

a solenoid magnet for generating a magnetic field in the axial direction

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 5

a circular accelerator comprising: a particle source for generating charged particles, a first accelerator for accelerating the charged particles generated by the particle source in a radial direction, a second accelerator for accelerating the charged particles along an axial direction extending in parallel with the axis of the solenoid magnet, and a solenoid magnet for generating a magnetic field in the axial direction

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4383955B1Circular accelerator and particle beam treatment system
Publication Date: 2026.05.20 HITACHI HIGH TECH CORP
  • EP4383955B1 patent drawingFigure 1
  • EP4383955B1 patent drawingFigure 2
  • EP4383955B1 patent drawingFigure 3

AI summary

There is provide a circular accelerator and a particle beam therapy system that can improve the beam extraction efficiency. A circular accelerator (1) that accelerates and extracts charged particle beams circulating in a magnetic field includes a first magnetic field region (26) in which closed trajectories of the beams with different energies are eccentric and which has a magnetic field gradient decreasing in the magnetic field toward an outer peripheral side and a second magnetic field region (27) having a magnetic field gradient increasing in the magnetic field toward the outer peripheral side. A border (28) between the first magnetic field region and the second magnetic field region is located on a downstream side in a traveling direction of the beam with respect to a predetermined region (16) in which an interval between the closed trajectories of the beams with the different energies is narrowest.