Cyclotron Magnetic Field Zoning for Stable Ion Beam Extraction
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Solution Overview
Problem
The existing particle therapy systems face inefficiencies in ion beam extraction due to increased amplitude in the vertical direction, which decreases extraction efficiency.
Innovation Solution
An accelerator system with a main magnetic field generation device, an extraction channel, and a disturbance magnetic field region that includes specific magnetic field strength gradients to guide the ion beam to the extraction channel, improving extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the ion beam passes through peeler magnetic field and regenerator magnetic field to increase horizontal amplitude for extraction, then the ion beam can be extracted from the circular accelerator, but the vertical amplitude also increases which decreases extraction efficiency
Solution Approach 1:
The magnetic field region is segmented into three distinct zones: peeler magnetic field region, regenerator magnetic field region, and flattening magnetic field region. Each region performs a specific function - the peeler increases horizontal amplitude, the regenerator maintains horizontal amplitude while reducing vertical amplitude, and the flattening reduces vertical amplitude further. This segmentation allows independent optimization of horizontal and vertical amplitude control, resolving the contradiction between achieving extraction and maintaining extraction efficiency.
Solution Approach 2:
The regenerator magnetic field region acts as an intermediary between the peeler and flattening regions. It receives the ion beam with increased horizontal amplitude from the peeler, maintains this horizontal amplitude through resonance, while simultaneously reducing vertical amplitude. This intermediary function allows the system to achieve the desired horizontal displacement for extraction while preventing excessive vertical amplitude growth that would reduce extraction efficiency.
2Ease of operation
If the amplitude of ion beam in vertical direction increases due to resonance, then horizontal amplitude increases for extraction, but extraction efficiency decreases
Solution Approach 1:
Different regions of the magnetic field system are assigned different local qualities or characteristics. The peeler region has strong gradient to rapidly increase horizontal amplitude. The regenerator region has specific gradient characteristics that maintain horizontal resonance while providing vertical damping. The flattening region has gradients optimized for vertical amplitude reduction. This local quality differentiation allows each region to perform its specific function, resolving the contradiction between achieving extraction capability and maintaining extraction efficiency.
3Device complexity
If a static main magnetic field is used in a cyclotron or synchronous cyclotron, then the accelerator structure is simplified, but the energy of ion beam taken out is fixed requiring external degrader for energy adjustment
Solution Approach 1:
The system introduces dynamic elements into the static main magnetic field structure through the peeler, regenerator, and flattening magnetic field regions. These regions can be dynamically activated to modify the magnetic field configuration, allowing the extraction energy to be varied by changing which regions are active and their respective field strengths. This maintains the simplicity of the static main magnetic field while adding the versatility needed for energy adjustment without requiring external degraders.
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
Enhances ion beam extraction efficiency by stabilizing the ion beam's trajectory and reducing vertical amplitude, allowing for more precise and efficient energy adjustment and extraction of ion beams within a predetermined range.
Implementation Method 1
accelerates an ion beam while circulating the ion beam by a main magnetic field
Implementation Method 2
a disturbance magnetic field region provided on an outer peripheral portion of the main magnetic field region, the disturbance magnetic field region being configured to excite a magnetic field that disturbs the ion beam displaced outward and guides the ion beam to the extraction channel
Implementation Method 3
accelerates the ion beam circulating in the circular accelerator to desired energy, and then feeds a radiofrequency electric field
Implementation Method 4
The ion beam to which the radiofrequency electric field is fed passes through a magnetic field region called a peeler magnetic field and a regenerator magnetic field in which an amplitude in a horizontal direction of betatron oscillation, which is oscillation centered on a central orbit, gradually increases to generate resonance of the betatron oscillation
Data Source
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AI summary
A disturbance magnetic field region provided in an outer peripheral portion of a main magnetic field region of an accelerator has a peeler region in which a strength of a magnetic field decreases toward an outside, a regenerator region in which the strength of the magnetic field increases toward the outside, and a substantially flat region in which the strength of the magnetic field is larger than the strength of the magnetic field of the peeler region and smaller than the strength of the magnetic field of the regenerator region.