EDX Sensor Shielding With Biased Electrode for Electron Rejection
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Solution Overview
Problem
Energy dispersive x-ray spectroscopy (EDX) systems face challenges in protecting x-ray sensors from impinging electrons while maintaining a high solid angle and preventing hazards associated with high voltages, which can distort the photon energetic spectrum and pose safety risks.
Innovation Solution
An EDX sensing unit is designed with a protective unit featuring a voltage biased electrode that alters the properties of electrons emitted from the sample, preventing them from reaching the x-ray sensor, and includes a charge dissipative dielectric coating to reduce arcing and charge accumulation, ensuring safety and minimal distortion of the photon spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective unit is introduced to block electrons from reaching the x-ray sensor, then the sensor is protected from electron damage, but the solid angle for x-ray collection is reduced
Solution Approach 1:
The protective unit features a voltage-biased electrode with a localized electric field that selectively deflects electrons while allowing x-rays to pass through. The electrode structure is designed with specific geometry (ring-shaped or cup-shaped) that creates a focused protective zone around the sensor without blocking the broader x-ray collection area, thus maintaining high solid angle while providing electron protection.
2Reliability
If high voltage is applied to the voltage biased electrode to deflect electrons, then electron protection is improved, but safety hazards increase due to high voltage arcing
Solution Approach 1:
A charge dissipative dielectric coating is applied to the voltage-biased electrode as an intermediary layer. This coating allows the electrode to maintain high voltage for effective electron deflection while the dielectric material prevents charge accumulation and reduces the risk of arcing to surrounding structures, thereby mitigating safety hazards.
Solution Approach 2:
The voltage-biased electrode is designed with a specific geometry (ring-shaped or cup-shaped) that creates an equipotential surface, distributing the high voltage uniformly across the electrode structure. This reduces electric field concentration at sharp edges or corners, minimizing the likelihood of arcing and improving safety.
3Productivity
If the protective unit is positioned close to the sample to maintain high solid angle, then x-ray collection efficiency is improved, but electron contamination of the sensor increases
Solution Approach 1:
The voltage-biased electrode acts as an intermediary barrier positioned between the sample and the x-ray sensor. It is located close enough to the sample to protect the sensor from electrons while maintaining a large solid angle for x-ray collection. The electrode's electric field selectively interacts with electrons (deflecting them) while being transparent to x-rays.
4Reliability
If the voltage biased electrode is made larger to improve electron protection, then electron blocking is enhanced, but distortion of the photon energetic spectrum increases
Solution Approach 1:
The voltage-biased electrode is designed with optimized dimensions and geometry (ring-shaped or cup-shaped) that provide sufficient electron protection coverage while minimizing the electrode's interaction with the x-ray photon path. The localized electric field is confined to regions where electron deflection is needed, reducing unnecessary interactions that could distort the photon energy spectrum.
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 solution effectively protects the x-ray sensor from electrons, maintains a large solid angle, and enhances safety by preventing arcing, while improving photon detection across the entire energy range, particularly benefiting energies below 1 keV.
Implementation Method 1
a protective unit featuring a voltage biased electrode that alters the properties of electrons emitted from the sample
Implementation Method 2
includes a charge dissipative dielectric coating to reduce arcing and charge accumulation
Implementation Method 3
The x-ray sensor is configured to (i) receive, by the one or more sensing regions, x-ray photons emitted from the sample
Data Source
AI summary
An energy-dispersive x-ray spectroscopy (EDX) sensing unit, the EDX sensing unit include a protective unit and an x-ray sensor that includes one or more sensing regions. The protective unit is configured to (i) introduce a change in one or more properties of electrons emitted from a sample, thereby preventing the electrons emitted from the sample from reaching the one or more sensing regions, the electrons are emitted from the sample due to an illuminating of the sample by a primary electron beam, and (ii) increase a safety of operation of the EDX sensing unit. The x-ray sensor is configured to (i) receive, by the one or more sensing regions, x-ray photons emitted from the sample due to the illuminating of the sample, and (ii) generate detection signals indicative of the x-ray photons.