Electron Diffraction Cooling Assembly for Stable Nanocrystal Positioning
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Solution Overview
Problem
Current electron diffraction systems face challenges in accurately characterizing nanocrystalline systems due to limitations in temperature control and sample positioning, leading to instability and reduced throughput in data collection.
Innovation Solution
A high-vacuum system with a cooling assembly that uses a flexible, conductive cooling braid thermally-coupled to a cold finger submerged in liquid nitrogen, allowing for precise temperature control and rapid cooling of samples to within the target temperature range, combined with positioner stages for accurate sample positioning within the electron beam pathway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cooling assembly with a cold finger is used to cool the sample, then the sample temperature can be controlled within the target range (−140°C to −180°C), but the device complexity increases
Solution Approach 1:
The cold finger is nested within the vacuum chamber housing, and the cooling braid is integrated within the primary assembly structure. This nesting approach allows the cooling system to be compact and integrated without adding excessive external complexity, while still achieving the required temperature control range of −140°C to −180°C for the sample.
Solution Approach 2:
A cooling braid acts as an intermediary thermal conductor between the cold finger and the sample holder. This flexible, conductive material efficiently transfers thermal energy from the cold finger to the sample, enabling precise temperature control while allowing for positional adjustments and reducing direct mechanical complexity.
2Manufacturing precision
If positioner stages are used to accurately position the sample, then the sample positioning precision is improved, but the device complexity increases
Solution Approach 1:
The positioner stages are designed to perform multiple functions: they not only position the sample in three-dimensional space but also provide stabilization during data collection and enable rapid repositioning for different sampling locations. This multi-functionality reduces the need for separate positioning and stabilization mechanisms, thereby limiting the increase in device complexity while improving positioning precision.
Solution Approach 2:
The positioner stages are designed with dynamic adjustment capabilities, allowing for precise positioning during data collection and rapid repositioning when needed. This dynamic design enables the system to adapt to different experimental requirements, improving positioning precision while maintaining operational flexibility and avoiding the need for overly complex static positioning mechanisms.
3Speed
If the sample is cooled rapidly to the target temperature range, then the temperature control speed is improved, but the stability of the cooling system may be reduced
Solution Approach 1:
The cooling assembly incorporates temperature monitoring and control mechanisms that provide feedback to the cooling system. This allows for rapid cooling to the target temperature range (−140°C to −180°C) while automatically adjusting the cooling rate to prevent thermal shock and maintain system stability. The feedback control ensures that the sample reaches the desired temperature quickly without compromising the overall stability of the cooling system.
4Reliability
If the housing is designed to hold a vacuum for stability, then the measurement reliability is improved, but the device complexity increases
Solution Approach 1:
The vacuum chamber housing is merged with the cooling assembly structure, integrating the vacuum containment function with the thermal management system. This consolidation reduces the number of separate components and interfaces, thereby limiting the increase in device complexity while still providing the stable vacuum environment required for reliable electron diffraction measurements.
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 stable and efficient characterization of nanocrystalline systems by maintaining samples at temperatures between −140°C and −180°C, enhancing data accuracy and throughput through precise temperature control and flexible sample positioning.
Implementation Method 1
The cooling braid 160 is configured to communicate thermal energy from the primary assembly into the cold finger 170 to cool the sample specimen
Implementation Method 2
an electron emitter 190 configured to transiently generate and accelerate an electron beam along the electron beam pathway
Implementation Method 3
Electron diffraction system for characterizing nanocrystalline structures
Data Source
AI summary
One variation of a system includes: a housing configured to hold a vacuum; a primary assembly; and a cooling assembly. The primary assembly includes: a sample receiver including a base section and a sample holder mounted to the base section and configured to transiently receive and retain a sample specimen; a receiver platform configured to receive and support the sample receiver; and a set of positioner stages flexibly coupled to the receiver platform and configured to transiently drive the sample holder to locate the sample specimen in a position intersecting an electron pathway. The cooling assembly includes: a cold finger defining an end submerged in a volume of coolant; and a conductive cooling braid coupled to the cold finger and to the primary assembly; and configured to communicate heat from the primary assembly into the cold finger to cool the sample specimen to temperatures within a target sample temperature range.