Synchrotron Bending Magnet Shim for Particle Therapy Beam Extraction
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Solution Overview
Problem
The efficiency of beam extraction from a synchrotron in particle therapy systems is limited due to beam loss during the formation of the separatrix, especially at low energy states, where the horizontal emittance of the circulating beam is not sufficiently attenuated, leading to increased collisions with electrodes and reduced extraction efficiency.
Innovation Solution
A particle therapy system employing a slow extraction method using the resonance of betatron oscillations, where the bending magnet's magnetic poles have a shim structure that adjusts the horizontal tune of the charged particle beam to approach a resonant line, generating an octupole magnetic field that decreases the horizontal tune as the amplitude of betatron oscillations increases, thereby improving extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the separatrix area for extraction is kept constant, then the orbit and current value of extracted beam are stable, but the efficiency of beam extraction is reduced due to beam loss during separatrix formation
Solution Approach 1:
The invention applies dynamics by making the separatrix area variable rather than constant. The horizontal tune is dynamically adjusted during extraction to optimize the separatrix area, allowing the system to adapt between stability requirements and extraction efficiency needs throughout the extraction process.
Solution Approach 2:
The invention changes the parameter of horizontal tune to control the separatrix area. By adjusting the horizontal tune, the separatrix area can be optimized to reduce beam loss while maintaining adequate stability, resolving the contradiction between these two requirements.
2Loss of substance
If the separatrix area for extraction is enlarged to reduce beam loss, then beam loss during extraction is reduced, but the turn separation between circulating and extracted beams decreases causing increased collisions with electrodes
Solution Approach 1:
The invention uses parameter changes of the horizontal tune to optimize the separatrix area, balancing beam loss reduction with turn separation maintenance. This dynamic parameter adjustment allows the system to achieve both reduced beam loss and adequate turn separation.
Solution Approach 2:
The system dynamically adjusts the horizontal tune during extraction to maintain optimal separatrix area, preventing both excessive beam loss and excessive turn separation that would cause electrode collisions.
3Loss of substance
If the horizontal emittance of circulating beam is not sufficiently attenuated at low energy states, then beam loss during extraction increases, but reducing energy further extends therapy time
Solution Approach 1:
The invention changes the horizontal tune parameter to optimize extraction conditions at low energy states, reducing beam loss without requiring additional energy attenuation time, thus resolving the contradiction between beam loss and therapy time.
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 enhances beam extraction efficiency, reduces beam loss, and shortens the time required for therapy by allowing more precise control over the beam's trajectory and reducing collisions with electrodes, thereby increasing the usable beam current for medical treatment.
Implementation Method 1
the horizontal tune of a charged particle more closely approach a resonant line used in the slow extraction method as the amplitude of the horizontal betatron oscillation of a charged particle included in the charged particle beam becomes larger
Implementation Method 2
magnetic poles included in the bending magnet have a shim structure that generates a magnetic field distribution
Implementation Method 3
generating an octupole magnetic field that decreases the horizontal tune as the amplitude of betatron oscillations increases
Implementation Method 4
the synchrotron extracts the charged particle beam, which circulates in the synchrotron, out of the synchrotron by means of a slow extraction method using the resonance of a betatron oscillation
Data Source
AI summary
A particle therapy system in which the efficiency of extracting a beam from a synchrotron can be improved and time required for therapy can be shortened is provided. The synchrotron 10 of the particle therapy system 100 extracts a charged particle beam, which circulates in the synchrotron 10, out of the synchrotron 10 by means of a slow extraction method using the resonance of a betatron oscillation, and magnetic poles 73 included in a bending magnet 12 of the synchrotron 10 have a SIM structure that generates a magnetic field distribution that makes the horizontal tune of the charged particle more closely approach a resonant line used in the slow extraction method as the amplitude of the horizontal betatron oscillation of a charged particle included in the charged particle beam becomes larger.