Beam Transport Chromatic Aberration Nullification

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Solution Overview

Problem

Current beam transport systems, particularly those using small-sized synchrotrons, struggle to effectively nullify chromatic aberration at the irradiation position, leading to beam position and diameter issues, and require high-performance electromagnets, increasing system complexity and cost.

Innovation Solution

The system sets excitation currents for bending and quadrupole electromagnets based on calculated optical parameters that account for the start-point momentum dispersion function and initial conditions at the irradiation position, using profile data to adjust and nearly eliminate chromatic aberration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high-performance electromagnets are used to nullify chromatic aberration, then beam positioning accuracy is improved, but device complexity and cost increase

Engineering Contradiction:
Improvebeam positioning accuracyVSAvoidelectromagnet system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the operational parameters of existing electromagnets by dynamically adjusting excitation currents based on detected beam position and diameter. Instead of using high-performance electromagnets with fixed strong fields, the system achieves chromatic aberration nullification by modulating the current parameters of standard electromagnets in response to real-time beam measurements

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback control system where beam position and diameter are continuously detected by measurement devices, and the detected values are used to adjust the excitation currents of electromagnets. This closed-loop feedback mechanism enables accurate beam positioning without requiring high-performance electromagnets, as the system self-corrects using standard components

Inventive Principle:
Principle #23Feedback

2Manufacturing precision

If high-performance electromagnets are used to control beam diameter, then beam diameter precision is improved, but manufacturing cost increases

Engineering Contradiction:
Improvebeam diameter control precisionVSAvoidsystem manufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent achieves precise beam diameter control by dynamically changing the excitation current parameters of existing electromagnets rather than employing expensive high-performance electromagnets. The system detects beam diameter and adjusts electromagnetic field strength through current modulation, achieving precise control with standard components

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses feedback control where beam diameter is detected by measurement devices and the detected values are fed back to adjust excitation currents. This enables precise beam diameter control through iterative correction using standard electromagnets, avoiding the need for costly high-performance components

Inventive Principle:
Principle #23Feedback

3Reliability

If the beam transport system is designed with ideal optical parameters, then chromatic aberration is reduced, but the system requires high-performance electromagnets increasing complexity

Engineering Contradiction:
Improvechromatic aberration controlVSAvoidelectromagnet performance requirements
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent transitions from static optical parameter design to dynamic control by continuously adjusting excitation currents based on real-time beam measurements. Instead of relying on fixed ideal optical parameters requiring high-performance electromagnets, the system adapts its electromagnetic fields dynamically to maintain optimal beam transport with standard components

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements feedback control where beam position and diameter measurements are used to adjust excitation currents, creating a self-regulating system that maintains reliable chromatic aberration control without requiring high-performance electromagnets. The feedback loop continuously optimizes the electromagnetic fields to achieve ideal optical behavior

Inventive Principle:
Principle #23Feedback

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 approach allows for accurate beam positioning and diameter control at the irradiation position, reducing the need for high-performance electromagnets and minimizing system complexity, thus lowering costs and improving beam transport efficiency.

Implementation Method 1

at least one bending electromagnet (7, 7b) that deflects the charged particle beam (31)

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

at least two quadrupole electromagnets (8, 8a to 8h) that focus or defocus the charged particle beam (31)

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP3020451B1Beam transport system and particle therapy device
Publication Date: 2020.04.22 HITACHI LTD
  • EP3020451B1 patent drawingFigure 1
  • EP3020451B1 patent drawingFigure 2~3
  • EP3020451B1 patent drawingFigure 4~6

AI summary

The object is to provide a beam transport system that can nearly nullify a chromatic aberration of a beam at an irradiation position of the beam even when it is a beam emitted from a small-sized synchrotron. According to a beam transport system (4) of the invention, it is characterized in that: based on a beam temporal-variation related amount that has been calculated by a beam analyzer (14) and that is a beam-position temporal variation amount or a beam diameter at a beam profile monitor (11), an optical parameter calculator (17) calculates a start- point momentum dispersion function that is a momentum dispersion function (η, η') of a charged particle beam (31) at a start point (S) in design of the beam transport system (4) that is set on a beam trajectory of the accelerator (3); and calculates optical parameters using, as an initial condition, the start-point momentum dispersion function and a beginning condition at an irradiation position (T) at the time of detecting profile data.