Magnetron Internal Modulation for SRF Cavity Phase Control
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Solution Overview
Problem
Traditional RF sources for superconducting pulsed accelerators, such as klystrons and solid-state amplifiers, are expensive and inadequate for providing individual phase and power control to each SRF cavity, leading to instability and high costs in large-scale projects, while existing magnetrons lack efficient pulsed operation without high-voltage modulators.
Innovation Solution
A system utilizing one or more magnetrons with internal modulation, powered by a DC power supply below the self-excitation threshold, using a pulsed RF input signal to generate pulsed RF power, allowing for phase and power control through injection-locking and eliminating the need for high-voltage modulators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional RF sources (klystrons, solid-state amplifiers) are used, then reliable RF power generation is achieved, but the system cost becomes excessively high and individual cavity control is inadequate
Solution Approach 1:
The patent replaces expensive traditional RF sources (klystrons, solid-state amplifiers) with inexpensive magnetrons. Although magnetrons have shorter operational lifespan compared to traditional sources, their extremely low cost allows individual installation in each SRF cavity, enabling independent phase and power control without significantly increasing overall system cost. This resolves the contradiction by accepting shorter component life in exchange for dramatically reduced device complexity and cost.
Solution Approach 2:
The patent divides the RF power generation system into multiple independent magnetron units, each feeding a specific SRF cavity. This segmentation allows individual phase and power control for each cavity, overcoming the limitation of traditional centralized RF sources that can only control the vector sum of accelerating voltage for a group of cavities. The segmentation principle enables precise local control while using low-cost components.
2Power
If magnetrons are operated above self-excitation threshold voltage, then sufficient RF power output is achieved, but the magnetron lifespan decreases and operational noise increases
Solution Approach 1:
The patent employs pulsed operation mode where magnetrons are switched on and off periodically rather than continuous operation. The magnetron is powered by a DC power supply at a voltage level below the self-excitation threshold voltage and uses internal modulation with a pulsed RF input signal to produce pulsed RF power output. This periodic activation reduces cumulative stress and thermal load on the magnetron, extending its operational lifespan while maintaining sufficient average RF power output for accelerator operation.
Solution Approach 2:
The patent changes the operating voltage parameter of the magnetron from above self-excitation threshold to below self-excitation threshold. By operating at subcritical voltage levels and using pulsed RF input signals for internal modulation, the magnetron achieves reliable pulsed power generation with reduced stress, lower operational noise, and extended lifespan while still meeting the power requirements of the accelerator system.
3Ease of operation
If magnetrons are operated without internal modulation, then simpler control is achieved, but phase and power control precision insufficient for SRF cavity stability requirements
Solution Approach 1:
The patent implements internal modulation within the magnetron itself, where a pulsed RF input signal modulates the magnetron's output. This self-service approach allows the magnetron to perform both power generation and phase/power control functions internally, eliminating the need for complex external modulation systems. The internal modulation mechanism provides precise phase and power control for each cavity while maintaining operational simplicity, as the magnetron autonomously responds to the pulsed input signal.
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 reduces costs by using magnetrons to stabilize voltage and phase in each SRF cavity, achieving efficient pulsed RF power generation with precise control, minimizing longitudinal beam emittance and operational noise, and extending the lifespan of the magnetron.
Implementation Method 1
configured to operate with internal modulation using a pulsed RF input signal to produce the pulsed RF power
Implementation Method 2
allowing for phase and power control through injection-locking
Implementation Method 3
when being powered by a direct-current (DC) power supply at a voltage level below the self-excitation threshold voltage
Data Source
AI summary
A system uses one or more magnetrons to generate pulsed radio-frequency (RF) power, such as for powering an accelerating cavity. The one or more magnetrons each having a self-excitation threshold voltage and configured to operate with internal modulation using a pulsed RF input signal to produce the pulsed RF power when being powered by a direct-current power supply at a voltage level below the self-excitation threshold voltage.