Hybrid Standing Wave Linear Accelerator RF Power Redistribution
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Solution Overview
Problem
Linear accelerators face inefficiencies in operating over a broad radiation beam energy range due to reduced capture and electron beam current, particularly at lower energies, leading to suboptimal radiation beam intensity and dose rate, especially in magnetron-driven and high-frequency systems.
Innovation Solution
A hybrid linear accelerator design combining a collinear standing wave and traveling wave section with RF power redistribution and phase adjustment via RF switches, phase shifters, and power adjusters to optimize energy and dose rate across a range of energy values, decoupling the sections and using RF power efficiently between them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a linear accelerator operates over a broad radiation beam energy range, then energy versatility is improved, but capture and electron beam current are reduced
Solution Approach 1:
The linear accelerator is divided into multiple independently controllable RF cavities, each capable of being individually adjusted in terms of RF power, phase, and coupling. This segmentation allows the accelerator to optimize electron capture and beam current for different energy ranges by selectively adjusting specific cavity parameters without affecting the entire structure.
Solution Approach 2:
The patent implements dynamic adjustment capabilities for RF power distribution and phase relationships across different cavity sections. By dynamically reconfiguring the RF fields in response to the desired output energy level, the system maintains high electron capture and beam current across a broad energy range from low to high energies.
2Adaptability or versatility
If RF power is varied to regulate output energy, then energy regulation is improved, but field structure changes reduce electron beam current
Solution Approach 1:
Different sections of the linear accelerator are assigned different RF power levels and phase relationships based on local requirements. When regulating output energy, the system adjusts RF parameters in specific cavity sections rather than uniformly across the entire structure, preserving favorable field structures in critical regions for maintaining electron beam current.
Solution Approach 2:
The patent changes multiple RF parameters simultaneously - not just RF power but also phase relationships and coupling conditions - to regulate output energy while maintaining optimal field structures for electron capture and beam current. This multi-parameter adjustment allows energy regulation without the detrimental field structure changes that would otherwise reduce beam current.
3Quantity of substance
If input RF power is increased to maintain radiation beam intensity, then power consumption increases, but electron beam current is reduced due to degraded capture
Solution Approach 1:
The system incorporates feedback mechanisms that monitor electron capture efficiency and beam current, and automatically adjust RF power distribution and phase relationships in different cavity sections. This feedback control ensures operation at optimal efficiency points, maintaining radiation beam intensity while minimizing RF power consumption by preventing capture degradation.
4Power
If the accelerator structure is optimized for high energy output, then maximum energy is improved, but performance at lower energies deteriorates
Solution Approach 1:
The accelerator structure is segmented into multiple cavity sections that can be independently optimized for different energy ranges. Sections can be configured with appropriate RF power levels, phase relationships, and coupling conditions to provide high energy output when needed, while simultaneously maintaining favorable field structures for low energy performance in other sections.
Solution Approach 2:
The patent creates a multi-functional accelerator structure where the same physical infrastructure can efficiently deliver both high energy and low energy beams. By implementing independent RF control of cavity sections with adjustable phase and power relationships, the system achieves universality in performance across the entire energy spectrum rather than being optimized for a single energy range.
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
The hybrid design enhances capture and efficiency, increasing electron beam current and radiation dose rate, particularly at lower energies, while maintaining high output at maximum energies, thus improving the overall performance and operational range of linear accelerators.
Implementation Method 1
a standing wave linear accelerator section configured to receive the input beam of charged particles and to accelerate the charged particles to provide an intermediate beam of accelerated electrons
Implementation Method 2
A traveling wave linear accelerator section is configured to receive the intermediate beam of accelerated electrons, and to further increase the momentum and energy of the accelerated electrons
Implementation Method 3
A drift tube is provided between the standing wave linear accelerator section and the traveling wave linear accelerator section to provide RF decoupling between the standing wave linear accelerator section and the traveling wave linear accelerator section
Data Source
AI summary
A hybrid linear accelerator is disclosed comprising a standing wave linear accelerator section (“SW section”) followed by a travelling wave linear accelerator section (“TW section”). In one example, RF power is provided to the TW section and power not used by the TW section is provided to the SW section via a waveguide. An RF switch, an RF phase adjuster, and/or an RF power adjuster is provided along the waveguide to change the energy and/or phase of the RF power provided to the SW section. In another example, RF power is provided to both the SW section and the TW section, and RF power not used by the TW section is provided to the SW section, via an RF switch, an RF phase adjuster, and/or an RF power. In another example, an RF load is matched to the output of the TW section by an RF switch.