Multi-Energy X-Ray Pulse Generation for Cargo Inspection
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Solution Overview
Problem
Existing cargo inspection systems using interlaced X-ray energy sources are limited by slow inspection speeds due to the need for two pulses separated in time, which is not suitable for fast-moving cargo, and struggle with effective material discrimination in high-energy regimes where atomic number dependence is weak.
Innovation Solution
A method is developed to generate a multiple-energy X-ray pulse by modulating the electron beam and RF field within a single pulse, allowing for distinct endpoint energies and flux variations, optimizing the coupling coefficient for zero RF power reflection, and impinging accelerated electrons on a target to produce Bremsstrahlung X-rays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interlaced dual-energy X-ray pulses are used for material discrimination, then material identification capability is improved, but inspection speed deteriorates due to the need for two separate pulses
Solution Approach 1:
The electron beam current pulse is segmented into multiple distinct current levels within a single pulse duration, with each current level generating X-rays at a specific energy. This allows multiple energies to be produced sequentially within one pulse rather than requiring separate pulses for each energy level.
Solution Approach 2:
The electron beam current is dynamically modulated during the pulse duration, transitioning between different current levels at controlled times. This dynamic current modulation enables the generation of multiple energy spectra within a single pulse, resolving the contradiction between material discrimination and inspection speed.
2Strength
If high-energy X-rays (several MeV) are used to penetrate thick cargo, then penetration capability is improved, but material discrimination capability deteriorates due to weak atomic number dependence in the high-energy regime
Solution Approach 1:
The X-ray energy parameter is changed during the pulse duration by modulating the electron beam current between different levels. This produces a sequence of X-ray photons with different energies within a single pulse, allowing material discrimination through Compton scattering effects while maintaining the ability to penetrate thick cargo with higher energy photons.
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 material discrimination while maintaining high scanning speeds, optimizing the X-ray dose to cargo and environment, and allows for dynamic control of the X-ray pulse profile, improving the effectiveness of cargo inspection systems.
Implementation Method 1
applying to the accelerating structure a radio frequency field with a specified RF field amplitude and a specified RF temporal profile... accelerating the beam of electrons with the radio frequency field within the accelerating structure
Implementation Method 2
impinging the accelerated electrons upon a target for generating Bremsstrahlung X-rays
Data Source
AI summary
Methods for generating a multiple-energy X-ray pulse. A beam of electrons is generated with an electron gun and modulated prior to injection into an accelerating structure to achieve at least a first and specified beam current amplitude over the course of respective beam current temporal profiles. A radio frequency field is applied to the accelerating structure with a specified RF field amplitude and a specified RF temporal profile. The first and second specified beam current amplitudes are injected serially, each after a specified delay, in such a manner as to achieve at least two distinct endpoint energies of electrons accelerated within the accelerating structure during a course of a single RF-pulse. The beam of electrons is accelerated by the radio frequency field within the accelerating structure to produce accelerated electrons which impinge upon a target for generating Bremsstrahlung X-rays.