Cryogenic Sample Holder With Switchable Thermal Contact
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Solution Overview
Problem
Existing cryogenic devices, such as 3He-4He dilution refrigerators, face challenges in efficiently cooling samples to low temperatures due to high thermal resistance at microscopic contact surfaces, leading to slow and costly cooling processes, especially when using Pulsed Tube Cryo-coolers with limited cooling capacity.
Innovation Solution
A holder with switchable contact means that can transition between thermal contact and non-contact modes, utilizing spring elements and coupling arms to establish thermal contact with the vacuum space walls without friction, allowing for minimal heat generation during sample insertion and removal, enabling rapid and efficient cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a sample is firmly screwed to the mixing chamber to achieve good heat transport, then thermal contact is improved, but the complexity of sample replacement increases and cooling time is extended
Solution Approach 1:
The patent employs a dynamic contact mechanism where spring elements can transition between contact and non-contact states. The contact bodies are movable along the probe axis, allowing them to be in thermal contact with the mixing chamber during cooling operations but separable when sample replacement is needed. This dynamic capability resolves the contradiction by enabling good thermal contact during operation while facilitating rapid sample replacement.
Solution Approach 2:
The patent divides the thermal contact function into separate movable contact bodies that can be independently controlled. These contact bodies are segmented from the main probe structure and can be positioned independently to establish or break thermal contact as needed. This segmentation allows the system to achieve both stable thermal contact for cooling and easy separation for sample replacement.
2Power
If liquid helium is used for cooling, then cooling capacity is sufficient, but operational costs increase
Solution Approach 1:
The patent introduces an intermediary thermal contact mechanism that improves heat transfer efficiency between the sample and the cooling system. The spring-loaded contact bodies ensure optimal thermal contact without requiring excessive cooling capacity, thereby reducing the amount of liquid helium needed while maintaining sufficient cooling performance.
3Ease of operation
If a probe is pushed inward to insert a sample, then sample insertion is achieved, but heat is generated that can overheat the dilution refrigerator
Solution Approach 1:
The patent implements preliminary thermal contact establishment before sample insertion. The contact bodies are positioned and spring-loaded to be ready to establish thermal contact with the mixing chamber before the sample is fully inserted. This preliminary action allows heat to be managed during the insertion process, preventing temperature instability while maintaining ease of operation.
4Productivity
If thermal contact is maintained continuously, then cooling efficiency is maximized, but sample replacement becomes time-consuming
Solution Approach 1:
The patent employs dynamic contact bodies that can transition between contact and non-contact states. During cooling operations, the contact bodies are pressed against the mixing chamber by spring elements to maximize thermal contact and cooling efficiency. When sample replacement is needed, the contact bodies can be retracted or moved away, allowing rapid sample exchange without maintaining continuous thermal contact. This dynamic control resolves the contradiction between cooling efficiency and sample replacement speed.
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 holder allows for simple and rapid sample insertion and removal while maintaining the desired low temperature, minimizing heat dissipation and reducing cooling time, with demonstrated cooling capacities ranging from 500 mW to 1 μW at various temperatures.
Implementation Method 1
a spring element (3, 3') manufactured from a heat-conducting, elastically deformable material
Implementation Method 2
a spring element (3, 3') manufactured from a heat-conducting, elastically deformable material
Data Source
AI summary
Holder (1) for a sample to be cooled to a low temperature in a vacuum space, comprising a carrier body (2) for carrying the sample in thermal contact and contact means (3, 4, 5) for bringing the carrier body into thermal contact with a cooling body to be brought to the low temperature, wherein the contact means can be switched between a first mode, in which there is no thermal contact between the carrier body and the cooling body, and a second mode in which there is thermal contact between the carrier body and the cooling body, and a probe for inserting into a vacuum space in a refrigerator such a holder for a sample to be cooled to a low temperature in this vacuum space, and a refrigerator, in particular a 3He-4He dilution refrigerator, adapted to accommodate such a probe.