APF Linear Ion Accelerator Electrode Length Oscillation
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Solution Overview
Problem
Conventional APF linear ion accelerators face challenges in reducing overall length and achieving high current acceleration, particularly for protons, due to the need for extensive length and increased space charge effects, which result in beam divergence and reduced transmission efficiency.
Innovation Solution
The APF linear ion accelerator employs a configuration with a radio frequency electric field applied through a coaxial tube and coupler to cylindrical electrodes with varying lengths, where the electrode length includes a velocity-dependent component and an oscillation component that changes cyclically, allowing for a reduced number of electrodes and a shorter overall length, while maintaining high energy acceleration and improved focusing forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the acceleration phase is changed by about ±π/2 to increase beam focusing force, then the beam focusing force is improved, but the effective radio frequency acceleration electric field is reduced, requiring more acceleration gaps and extending the accelerator length
Solution Approach 1:
The invention changes the parameter of acceleration phase from conventional ±π/2 to a smaller range, and modifies the electrode length parameter to compensate. By making electrode lengths proportional to ion beam velocity and adding oscillation components, the system achieves adequate focusing force while maintaining effective acceleration electric field, thus reducing accelerator length
Solution Approach 2:
The invention introduces dynamic adjustment of electrode lengths that oscillate around velocity-proportional values. This dynamic modulation of electrode geometry allows the system to provide variable focusing strength while maintaining efficient acceleration, resolving the trade-off between focusing force and accelerator length
2Use of energy by moving object
If the number of drift tubes is increased to accelerate ion beam to high energy, then the acceleration energy is improved, but the overall length of the accelerator is extended
Solution Approach 1:
The invention optimizes the parameter relationship between electrode length and ion beam velocity, making electrode lengths directly proportional to velocity. This parameter optimization improves acceleration efficiency, allowing high energy to be achieved with fewer drift tubes and shorter accelerator length
Solution Approach 2:
The invention employs periodic oscillation of electrode lengths around their velocity-proportional values. This periodic modulation enhances the acceleration process efficiency, enabling faster energy gain per unit length and reducing the total number of drift tubes required
3Force
If the acceleration phase is greatly changed to increase focusing force, then the beam focusing is improved, but the oscillation in electrode length increases, affecting transmission efficiency
Solution Approach 1:
The invention changes the acceleration phase parameter to a moderate range and compensates by adjusting electrode length parameters. This parameter transformation allows achieving adequate focusing force without excessive phase oscillation, thereby maintaining high transmission efficiency
Solution Approach 2:
The invention introduces dynamic oscillation of electrode lengths that is controlled and limited in amplitude. This controlled dynamic adjustment provides necessary focusing force while preventing excessive oscillation that would reduce transmission efficiency, thus maintaining system reliability
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 configuration enables a shorter accelerator length, increased beam current, and enhanced transmission efficiency, reducing the space charge effect and allowing for higher current proton acceleration to high energies with improved focusing and reduced divergence.
Implementation Method 1
a radio frequency acceleration electric field is applied to the individual gaps. Thereafter, when an ion beam passes across one of the gaps (hereinafter referred to as acceleration gaps), the ion beam is accelerated by the radio frequency acceleration electric field applied to the gap
Implementation Method 2
the focusing force generated by the radio frequency electromagnetic field
Data Source
AI summary
The electrode lengths of a plurality of electrodes linearly arranged in an acceleration cavity are proportional to the velocity of a traveling ion beam. Further, the electrode length is so designated that, in each half of a predetermined cycle in the ion beam direction of travel, the absolute value of a difference, relative to a length that is proportional to the beam traveling velocity is equal to or greater than a value corresponding to the phase width of the traveling ion beam, is provided for electrodes that do not exceed three units and that are fewer than electrodes allotted to half the predetermined cycle.