Helium-3 Refrigerator Main Pipe Materials for Low-Background Magnetization
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Solution Overview
Problem
The existing helium 3 refrigerator-based magnetic property measurement systems face challenges with high background signals due to the ferromagnetic behavior of stainless steel materials, making it difficult to accurately measure magnetization at low temperatures and high magnetic fields, especially when using commercially available MPMS systems.
Innovation Solution
The system employs a helium 3 refrigerator with a main pipe constructed from titanium for the lower inner tube and copper for the outer and condensing tubes, reducing background hysteresis and signal interference, allowing for reliable magnetization measurements down to 0.3 K even at high magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stainless steel is used for the main pipe of the helium 3 refrigerator, then the structural strength and magnetic shielding are improved, but the background signal increases due to ferromagnetic behavior
Solution Approach 1:
The patent employs a composite structure where the main pipe is made of non-ferromagnetic material (such as aluminum or copper) to minimize background signal, while incorporating ferromagnetic material (stainless steel) in specific components like the sample holder or shielding elements where structural strength and magnetic field control are critical. This composite approach allows the system to achieve both low background signal and sufficient mechanical strength.
2Object-affected harmful factors
If stainless steel is used for the main pipe, then magnetic shielding is improved, but measurement precision deteriorates due to hysteresis in high magnetic fields
Solution Approach 1:
The patent applies local quality by using non-ferromagnetic material for the main pipe in regions where measurement precision is critical, while selectively incorporating ferromagnetic shielding materials only in specific locations where magnetic field control is needed but will not interfere with measurements. This localized application of different material properties maintains both shielding effectiveness and measurement accuracy.
3Temperature
If the measurement temperature is lowered below 1.8 K, then the study of low transition temperature materials is enabled, but the background signal from ferromagnetic materials becomes more significant
Solution Approach 1:
The patent changes the material parameter of the main pipe from ferromagnetic (stainless steel) to non-ferromagnetic material, fundamentally altering the magnetic properties of the system. This parameter change eliminates the temperature-dependent background signal issue that would otherwise worsen at lower temperatures, enabling precise measurements down to 0.3 K without ferromagnetic interference.
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
This configuration enables infallible magnetization measurements down to 0.3 K with reduced background noise, allowing for accurate detection of weakly magnetic samples and overcoming the limitations of previous systems.
Implementation Method 1
a helium 3 refrigerator-utilizing magnetic property measurement system adapted to generate a very low temperature reaching 0.3 K
Implementation Method 2
enabling a micromagnetic field generated by a magnetic sample fixed to the sample rod 5 to be detected with a SQUID that makes use of the Josephson effect of a superconducting junction
Implementation Method 3
the main pipe is formed, as recognized sequentially from top to bottom, of an upper supporting tube, a condensing tube, a lower inner tube and an outer tube to form an insulated vacuum chamber between itself and the lower inner tube
Implementation Method 4
a magnetic property measurement system (MPMS) provided with a tubular body for permitting insertion of the helium 3 refrigerator therein and a cooling means disposed on an outer periphery of the tubular body and operated with helium 4 and further provided with a superconducting magnet
Data Source
AI summary
In a helium 3 refrigerator-utilizing magnetic property measurement system (MPMS) which enables magnetization measurement to be effected until 0.3 K, a main pipe, to enable magnetization measurement to be infallibly effected even when the upper limit of a magnetic field the MPMS can induce is applied, includes an upper supporting tube positioned in the uppermost part and allowing a bellows to be connected to the lateral part thereof, a condensing tube supported in the lower part of the upper supporting tube, an outer tube fixed in the lower part of the condensing tube and adapted to form an outer wall of an insulated vacuum chamber, and a lower inner tube forming an inner wall of the insulated vacuum chamber. In each of the tubes, the lower inner tube is formed of titanium. As a result, a background signal can be decreased and the measurement can be infallibly effected until the upper limit of the magnetic field of the MPMS.