Cryogen-Free Sample Cooling with Multi-Stage ADR and Fast Loading
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Solution Overview
Problem
Current cryogen-free cooling devices for achieving low temperatures face limitations such as temporary cooling capabilities and low cooling power, making them unsuitable for continuous scientific applications, and they often require complex sample handling due to mechanical support, leading to significant heat leaks.
Innovation Solution
A cryogen-free cooling apparatus comprising a vacuum chamber with a first mechanical suspension of low thermal conductivity for the sample stage and a second cooling device, such as an adiabatic demagnetization refrigerator, allowing for continuous operation and rapid sample changing without the need for liquid cryogens, utilizing a multi-stage ADR system with heat switches and a superconducting magnet to achieve ultra-low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a mechanical support structure is used to strongly support the sample stage, then the sample stage stability is improved, but heat leaks increase significantly
Solution Approach 1:
The patent replaces the traditional mechanical support structure with a magnetic field-based support system. The sample stage is supported by magnetic forces generated by superconducting magnets, eliminating the need for direct mechanical contact and the associated heat conduction paths. This substitution allows the sample stage to be strongly supported while minimizing heat leaks to the base plate.
2Temperature
If a single-shot ADR method is used, then the cooling apparatus achieves ultra-low temperatures, but continuous operation is not possible
Solution Approach 1:
The patent implements a multi-stage ADR system where multiple adiabatic demagnetization refrigerators operate in sequence or parallel. When one ADR stage completes its cooling cycle, another stage is already preparing or has completed its cycle, ensuring continuous cooling capability. The system maintains ultra-low temperatures continuously by coordinating the operation of multiple ADR units rather than relying on a single-shot approach.
Solution Approach 2:
The cooling system is divided into multiple independent ADR stages, each capable of operating autonomously. This segmentation allows different stages to be at different points in their cooling cycles simultaneously, with one stage regenerating while another provides active cooling, thereby achieving continuous operation.
3Power
If a small cooling power ADR device is used, then the apparatus is compact and cost-effective, but rapid sample changing becomes impossible
Solution Approach 1:
The patent introduces a dynamic sample stage positioning system that can rapidly move the sample stage between different positions using magnetic forces or voice coil actuators. This dynamic positioning capability allows samples to be quickly changed or repositioned without requiring large mechanical support structures, maintaining compact device size while enabling rapid sample changing for high productivity.
4Power
If liquid cryogens are used for cooling, then high cooling power is achieved, but safety risks and operational complexity increase
Solution Approach 1:
The patent replaces liquid cryogen-based cooling systems with solid-state ADR technology. This substitution eliminates the need for liquid helium or nitrogen storage, handling, and replenishment operations. The ADR system achieves comparable or sufficient cooling power through adiabatic demagnetization of paramagnetic salts, dramatically reducing operational complexity and safety risks associated with cryogen handling while maintaining effective cooling capability.
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 continuous operation at ultra-low temperatures with improved cooling power and rapid sample changing capabilities, reducing heat leaks and operational complexity while eliminating the need for liquid cryogens, thus addressing the limitations of existing cryogen-free cooling technologies.
Implementation Method 1
One alternative cooling technology which is based on the magnetocaloric effect is the so-called adiabatic demagnetization refrigeration (ADR)
Implementation Method 2
Here, cooling technologies based on solid state refrigerants are particularly interesting as they can provide cooling power without the need of moving or circulating a refrigerant, e.g. magnetic coolers which may be based, e.g., on the magnetocaloric or barocaloric effect of a solid
Data Source
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AI summary
The disclosure relates to a cryogen-free cooling apparatus for cooling a sample, comprising a vacuum chamber, a first cooling device which is configured to generate a first temperature in the vacuum chamber to provide a main thermal bath, a second cooling device, which is in connection with a sample stage on which a sample is to be arranged, wherein the second cooling device is a solid state cooler which is configured to provide a second temperature to the sample stage, and wherein the second temperature is different from the first temperature, and a sample loading device which is configured to change the sample while operating the first cooling device and the second cooling device.