Circular Accelerator RF Kicker for Precise Beam Extraction
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Solution Overview
Problem
In synchrocyclotrons used for particle therapy, controlling the length of beam pulses and the amount of charge extracted is challenging due to variations in ion generation and radiofrequency field stability, leading to difficulties in achieving precise dose control for irradiation, which results in inefficient treatment times and patient throughput.
Innovation Solution
Applying a secondary radiofrequency wave with a different frequency than the acceleration wave to control the extraction of charged particle beams, allowing for precise adjustment of beam charge in each acceleration cycle using a radiofrequency kicker system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a scanning coil is used to scan the beam and beam energy is changed to adjust range in scanning irradiation, then the beam can be irradiated in conformity to the target shape, but high precision dose control for each irradiation spot becomes difficult to achieve due to variations in extracted beam charge
Solution Approach 1:
The patent changes the frequency parameter of the radiofrequency wave from the acceleration frequency to a different frequency (such as the betatron oscillation frequency) to enable precise control of the extracted beam charge. This parameter change allows the extraction amount to be controlled independently of the acceleration process, achieving both high dose control precision and beam charge stability.
2Manufacturing precision
If the extracted beam charge is reduced by adjusting the ion source or acceleration radiofrequency voltage to achieve low charge beam extraction, then dose control for each spot becomes possible, but the dose rate decreases and treatment time increases
Solution Approach 1:
Instead of reducing beam charge by adjusting ion source or acceleration voltage (which reduces dose rate), the patent changes the radiofrequency wave frequency applied during extraction. This allows precise dose control while maintaining high beam charge extraction, thereby preserving high dose rate and reducing treatment time.
3Measurement precision
If the amount of beam charge to be extracted is controlled by adjusting ion source generation or acceleration radiofrequency voltage, then some control over beam charge is achieved, but high precision control is difficult due to temporal variations in ion generation and field stability
Solution Approach 1:
The patent applies a radiofrequency wave at a frequency different from the acceleration frequency during the extraction phase. This parameter change decouples the extraction control from the acceleration process, eliminating the influence of temporal variations in ion generation and acceleration field stability, thereby achieving both high precision control and consistent beam charge extraction.
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 method enables high-precision control over the extracted beam charge, improving dose rate and reducing treatment time by allowing for more efficient irradiation without excess or deficiency, thereby enhancing patient throughput.
Implementation Method 1
a beam in the synchrocyclotron circulates in a temporally constant main magnetic field while increasing the curvature radius of orbit, so that the beam has energy and is accelerated every time the beam passes through an acceleration gap in which an acceleration radiofrequency electric filed is produced
Implementation Method 2
another radiofrequency wave with a frequency different from the radiofrequency wave used for acceleration is applied to the charged particle beam in order to extract the charged particle beam
Implementation Method 3
a beam in the synchrocyclotron circulates in a temporally constant main magnetic field while increasing the curvature radius of orbit
Data Source
AI summary
In a circular accelerator that applies a radiofrequency wave in a main magnetic field to accelerate charged particle beam while increasing an orbit radius, another radiofrequency wave with a frequency different from the radiofrequency wave used for acceleration is applied to the charged particle beam in order to extract the charged particle beam. Thereby, in the circular accelerator that accelerates charged particle beam while increasing an orbit radius by applying a radiofrequency wave in a main magnetic field, the high precision control on extraction of the charged particle beam from the circular accelerator is achieved.