Compact Ion Accelerator Magnetic Orbit Control for Variable Beam Energy
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Solution Overview
Problem
Existing accelerators, such as synchrocyclotrons and synchrotrons, face limitations in beam energy variability, efficiency, and dose rate in particle therapy due to fixed beam extraction cycles and inefficient beam injection, particularly in carbon beam therapy.
Innovation Solution
A compact accelerator design with a pair of magnetic poles, a radiofrequency acceleration cavity, and additional magnetic field generators to control closed orbits and enhance beam injection efficiency, allowing variable beam energy and increased dose rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the beam is injected at a position greatly shifted in the radial direction from the central axis (close to outer periphery), then the accelerator can extract ion beams of different energies by utilizing orbits inside the outermost orbit, but the beam injection efficiency is reduced due to the difficulty of introducing the beam at such a position
Solution Approach 1:
The patent applies dynamics by making the magnetic field distribution adjustable rather than fixed. The electromagnet's main magnetic field is designed to allow the centers of orbits to move gradually toward the central axis as the orbital radius increases, creating a dynamic orbit configuration that enables efficient beam injection at positions close to the outer periphery while maintaining the capability to extract beams of different energies
Solution Approach 2:
The patent utilizes parameter changes by varying the magnetic field distribution to control orbit positions. By adjusting the magnetic field intensity and distribution, the system can shift orbit centers toward the central axis, enabling flexible beam extraction at different energy levels while improving injection efficiency at peripheral positions
2Device complexity
If a synchrocyclotron is used with a fixed extraction cycle, then the accelerator structure is simplified, but the dose rate in particle therapy is reduced due to the inability to vary beam energy continuously
Solution Approach 1:
The patent applies universality by designing an accelerator system that can perform multiple functions: it maintains the simplified synchrocyclotron structure for basic operation while adding the capability to vary beam energy by controlling magnetic field distribution. This allows the same device to operate in both fixed-energy and variable-energy modes, serving both simplified operation and high-dose-rate therapy requirements
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 design enables efficient beam injection and variable beam energy, improving the dose rate in particle therapy systems.
Implementation Method 1
a radiofrequency acceleration cavity that is inserted into a cavity formed between the pair of magnetic poles and that generates a radio frequency for accelerating the ion beam circulating in the orbital plane
Implementation Method 2
an electromagnet that includes a pair of magnetic poles arranged opposite each other having an orbital plane for circulating an ion beam interposed therebetween and that forms a main magnetic field that generates a plurality of closed orbits on the orbital plane
Implementation Method 3
an additional magnetic field generator that is disposed on an outer periphery of the cavity, that feeds a magnetic field to the moving ion beam on one or more closed orbits of an outermost periphery and inside the outermost periphery such that the direction of movement of the ion beam is made to deviate from the closed orbits
Data Source
AI summary
As the ion beam is accelerated, the radii of the closed orbits gradually increase, and the centers thereof move in a direction approaching the peripheral edge portion along a predetermined radial direction of the cavity, and upon reversing the direction of movement, move further toward the center of the cavity. The intensity distribution in the orbital plane of the main magnetic field is designed to realize the foregoing feature. Thus, an accelerator is provided that is compact and that enables the energy of an extracted beam to be changed, that enhances the efficiency of beam injection into the accelerator from an external ion source, and that improves a dose rate of the resulting extracted ion beam.