Electron Microscope Orifice Diameter Control for Atmospheric Pressure Observation
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Solution Overview
Problem
Conventional electron microscopes are unable to observe the reaction process between a gas and a solid at atmospheric pressure due to the risk of electrical discharge and decreased electron beam penetrative power, limiting their ability to image reactions in conditions similar to real-world environments.
Innovation Solution
An electron microscope with a computer-controlled system that adjusts the diameter of orifices within the electron optical column to maintain optimal pressure and prevent electrical discharge, allowing for imaging at atmospheric pressure by selecting the appropriate orifice diameters and pumping sequence based on the gas species and pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gas is supplied to increase pressure around the specimen to atmospheric pressure, then the reaction process can be observed in real-world conditions, but electrical discharge occurs in the electron beam source and beam penetrative power decreases
Solution Approach 1:
The electron optical column is divided into multiple vacuum chambers separated by orifices. Each chamber can be independently pressure-controlled, allowing the specimen chamber to be at atmospheric pressure while beam source chambers remain under vacuum. This segmentation enables simultaneous achievement of real-world observation conditions and protection against electrical discharge.
Solution Approach 2:
Multiple orifices with adjustable diameters serve as intermediaries between vacuum and atmospheric pressure regions. These orifices control gas flow and pressure distribution, acting as mediators that allow atmospheric pressure at the specimen while maintaining vacuum conditions at the beam source, preventing electrical discharge.
2Quantity of substance
If orifice diameter is increased to allow atmospheric pressure at specimen, then gas flow is improved, but electron beam penetrative power decreases and resolution deteriorates
Solution Approach 1:
The orifice diameters are made dynamically adjustable rather than fixed. This allows the system to optimize the balance between gas flow quantity and beam quality by selecting appropriate orifice sizes for different imaging conditions, resolving the contradiction between atmospheric pressure requirements and beam penetrative power.
Solution Approach 2:
The system changes physical parameters (orifice diameters, gas flow rates, pressure levels) to achieve optimal performance. By adjusting these parameters, the system can maintain atmospheric pressure at the specimen while preserving sufficient beam penetrative power and resolution for high-quality imaging.
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
Enables observation of the reaction process between a gas and a solid at atmospheric pressure, maintaining the electron beam's penetrative and resolving power, thus facilitating the elucidation of reaction mechanisms in conditions closer to real-world ambients.
Implementation Method 1
at least one vacuum pump mounted in a given location of an electron optical column
Implementation Method 2
a plurality of orifices arranged inside the electron optical column and placed between the specimen and the electron beam source, each of the orifices being capable of changing its diameter
Implementation Method 3
an electron beam source for generating an accelerated electron beam
Implementation Method 4
electromagnetic lenses for focusing the accelerated electron beam
Data Source
AI summary
An electron microscope has an electron beam source generating an accelerated electron beam, electromagnetic lenses for converging the electron beam, alignment coils for adjusting the optical axis of the beam transmitted through the lenses, a control unit for controlling the ambient around a specimen, at least one vacuum pump mounted in a given location of the electron optical column, a gas inlet device mounted near the specimen, an imager for creating an image based on a signal arising from the region of the specimen illuminated with the beam, an image output device for recording and displaying the image, and a computer for controlling these components. The computer finds the orifices to be used and diameters of orifices at which the pressure is maintained without electrical discharge in an electron beam source from the selected gas species and the pressure around the specimen.