Dual RF Voltage Synchrotron Beam Extraction Control
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Solution Overview
Problem
Existing charged particle beam extraction systems face challenges in controlling beam extraction and stoppage, leading to overshoot currents and reduced accuracy during radiation therapy, particularly in particle therapy for cancer treatment.
Innovation Solution
A dual radiofrequency voltage control system is implemented, where a first voltage increases the beam's oscillation amplitude beyond the stability limit and a second voltage preferentially extracts the beam around the stability limit, with the second voltage's amplitude gradually increased during extraction to prevent overshoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single frequency radiofrequency voltage is superimposed on the extraction radiofrequency voltage to preferentially extract particles around the stability limit, then beam leakage during stoppage is prevented, but an overshoot current occurs when the next beam extraction is started
Solution Approach 1:
The extraction radiofrequency voltage is divided into two separate frequency components: a first radiofrequency voltage at the betatron oscillation frequency to increase oscillation amplitude and exceed the stability limit, and a second radiofrequency voltage at a frequency corresponding to the stability limit to preferentially extract particles around the stability limit. This segmentation allows independent control of each voltage component, enabling beam leakage prevention during stoppage while avoiding overshoot current during extraction start.
2Speed
If the radiofrequency voltage amplitude is increased to improve beam extraction speed, then responsiveness during beam extraction is improved, but an overshoot current is caused
Solution Approach 1:
The amplitudes of the first and second radiofrequency voltages are dynamically adjusted during beam extraction. The first radiofrequency voltage amplitude is controlled depending on the beam current to achieve rapid extraction, while the second radiofrequency voltage amplitude is gradually increased from zero at the start of extraction to prevent overshoot current. This dynamic adjustment maintains high extraction speed while ensuring beam current accuracy.
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 responsiveness and accuracy during beam extraction and stoppage, improving dose rate and reducing irradiation time, thereby achieving high-precision beam irradiation.
Implementation Method 1
a first radiofrequency voltage for increasing an oscillation amplitude of the beam so that the beam orbiting inside the synchrotron exceeds a stability limit
Implementation Method 2
a second radiofrequency voltage for preferentially extracting a charged particle beam orbiting around the stability limit... A frequency of the second radiofrequency voltage is set to a frequency corresponding to a natural oscillation frequency (tune) of the charged particle beam
Data Source
AI summary
When controlling the ejection of a charged particle beam from a synchrotron, a radiofrequency voltage is applied, which serves as the radio-frequency voltage to be applied to an ejection radio-frequency electrode equipping the synchrotron, and which is constituted by a first radio-frequency voltage for increasing an oscillation amplitude in such a way as to exceed a stable limit in order to eject to the exterior of the synchrotron a beam that circles inside the synchrotron, and a second radio-frequency voltage for preferentially ejecting a charged particle beam that circles in the vicinity of the stable limit, with the amplitude value of the second radiofrequency voltage being controlled in such a way that the amplitude value is 0 prior to the beam ejection start, the amplitude value increases gradually from the beam ejection start, and, once a predetermined amplitude value has been reached, this value is maintained.