Microwave Electron Accelerator RF Frequency Control
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Solution Overview
Problem
Current container inspection systems using radiofrequency electron accelerators face limitations in energy variation range, requiring significant latency times for switching between energy levels due to mechanical switching or phase changes, which restricts the precision and accuracy of identifying container contents.
Innovation Solution
A microwave electron acceleration device that varies the RF frequency of the accelerator, combined with beam current control and RF power adjustments, allowing for a wide range of energy variations by optimizing the accelerating section design, enabling rapid changes in energy levels without latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mechanical switching or phase change methods are used to vary electron energy levels, then energy variation is achieved, but significant latency time occurs due to mechanical switching or phase change duration
Solution Approach 1:
The patent replaces mechanical switching systems with electronic frequency modulation of the RF signal. Instead of using mechanical shunts or motors to change cavity phases, the invention modulates the RF frequency directly, eliminating mechanical moving parts and their associated switching latencies. This substitution of mechanical systems with electronic control achieves rapid energy variation without the time delays inherent in mechanical switching.
Solution Approach 2:
The patent implements dynamic energy control by continuously modulating the RF frequency in response to detection signals. The system dynamically adjusts the accelerator energy in real-time during the scanning process, allowing the electron beam energy to be varied rapidly without the fixed latency constraints of mechanical switching systems. This dynamic approach enables the system to adapt energy levels on-the-fly based on the specific inspection requirements.
2Adaptability or versatility
If beam current control or moderate RF power reduction is used to change electron energy, then energy adjustment is possible, but the energy variation range is restricted to typically a factor of two
Solution Approach 1:
The patent fundamentally changes the control parameter from beam current or RF power to RF frequency. By modulating the frequency of the accelerating RF signal, the system achieves a much broader energy variation range (typically a factor of 8 or more) compared to the limited factor of two range obtainable through beam current control. This parameter change enables flexible energy adjustment across a wide spectrum while maintaining full productivity and inspection capability.
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 allows for a much broader range of energy variations (typically a factor of 8) at the output of the linear accelerator, enabling faster and more precise identification of container contents with improved resolution and the ability to detect various materials based on their atomic number.
Implementation Method 1
The electrons are accelerated in the LINAC by suitably synchronized successive high-frequency pulses. The beam passing through a series of cavities where there is an alternating electric field will be able to reach an energy of a few MeV
Implementation Method 2
The high frequency sources used are almost always klystrons or magnetrons. The accelerator is excited by a microwave source 28 at a frequency f0.
Data Source
Figure 1
Figure 2a~2b
Figure 3a
AI summary
The invention relates to a microwave device for accelerating electrons, comprising an electron cannon (50) that provides an electron beam (54) along an axis ZZ' in a microwave structure (60) for accelerating the electrons of the beam, having, at one of the ends (62) thereof, on the electron cannon side, an input (66) for the electron beam, at the other end (64), an output (68) for the accelerated electrons, between the two ends of the structure, a series of n cavities C1, C2,... Ci,... Cx,... Cn coupled, along said axis ZZ', to a central resonance frequency fO, an input (74) for a microwave signal Urf for exciting the microwave structure by means of one of cavities C1 of the series of n cavities, a radiofrequency generator (76) providing the microwave excitation signal Urf to the microwave acceleration structure, a central processing unit UC (90) configured to control the energy variation of the electrons exiting the microwave structure. The radiofrequency generator (76) comprises a frequency-controlling input (78) for changing the frequency Fv of the microwave excitation signal Urf around the central resonance frequency fO, the change in the frequency Fv of the excitation signal producing a variation in the energy of the accelerated electrons of the beam exiting the microwave structure (60). The invention can be used for inspecting containers by irradiating photons or for medical radiation therapy.