A method for manufacturing a multiple-layer type cold head including a rare earth regenerator material particle
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional cold heads using rare earth regenerator materials suffer from deterioration of refrigerating capacity over time due to oxidation, leading to reduced long-term reliability and increased maintenance costs, with a typical guarantee period of 20000 to 30000 hours.
Innovation Solution
A method for manufacturing a multiple-layer type cold head using rare earth regenerator material particles with a controlled carbon content and surface adsorption of carbon and oxygen compounds, managed in an argon atmosphere or vacuum to prevent oxidation, and utilizing intermetallic compounds like HoCu2, Er3Ni, and Er3Co to enhance specific heat and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional rare earth regenerator material is used, then the initial refrigerating capacity is achieved, but the refrigerating capacity deteriorates over time due to oxidation
Solution Approach 1:
The patent applies composite materials by combining rare earth regenerator material particles with a protective coating layer. This coating layer acts as a barrier against oxidation while preserving the refrigerating capacity of the rare earth material, thereby achieving both long-term reliability and oxidation resistance simultaneously
Solution Approach 2:
The patent utilizes an inert atmosphere approach by controlling the oxidation environment during operation. The protective coating creates an inert barrier that prevents oxygen from reaching the rare earth regenerator material, effectively creating a localized inert environment that prevents oxidation over time
2Power
If the regenerator material is designed for high refrigerating capacity, then the initial performance is improved, but the material breaks down after 20000-30000 hours of operation
Solution Approach 1:
The patent applies beforehand cushioning by pre-applying a protective coating to the rare earth regenerator material particles before they are installed in the cold head. This coating serves as a preventive measure that cushions the material against oxidative damage throughout its operational life, extending the duration of action while maintaining high refrigerating capacity
3Reliability
If the cold head is designed with high airtightness to prevent helium leakage, then the sealing performance is improved, but the maintenance burden increases due to difficulty in replacing regenerator material
Solution Approach 1:
The patent applies segmentation by designing the cold head with modular components, including removable seals and access points. This allows the regenerator material to be replaced without compromising the overall airtightness of the system, thereby maintaining high sealing performance while significantly improving ease of repair and maintenance accessibility
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 method achieves a long-term reliability of over 40000 hours, maintaining refrigerating capacity and mechanical strength, thereby extending the operational life of superconducting magnets and examination apparatus like MRI machines beyond conventional limits.
Implementation Method 1
a specific heat per volume of the regenerator material is utilized to obtain the cryogenic temperature
Implementation Method 2
a rare earth compound, for example, is used. For example, by adjusting a particle size and an aspect ratio of a rare earth compound of Er 3 Ni, HoCu 2
Implementation Method 3
a surface region of the rare earth regenerator material particle group is analyzed by an X-ray photoelectron spectroscopy (XPS) analysis, a peak indicating a carbon component is detected in the surface region by the XPS analysis
Data Source
Figure 1
Figure 2~3
AI summary
A rare earth regenerator material particle and a regenerator material particle group having a high long-term reliability, and a superconducting magnet, an examination apparatus, a cryopump and the like using the same are provided. A rare earth regenerator material particle contains a rare earth element as a constituent component, and in the particle, a peak indicating a carbon component is detected in a surface region by an X-ray photoelectron spectroscopy analysis.