Cryogenic Cooling with Cylindrical Shielding Coils for Field Isolation
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Solution Overview
Problem
Conventional demagnetisation cooling systems require complex shielding designs with multiple coils and liquid cryogen immersion, leading to mechanical constraints and inefficiencies due to the need for precise magnetic field cancellation between powerful magnets, which complicates the achievement of ultra-low temperatures.
Innovation Solution
A cryogenic cooling apparatus using cylindrical superconducting shielding magnets with a single coil design, powered by a common current, to cancel magnetic fields effectively, eliminating the need for liquid cryogens and reducing mechanical constraints, and incorporating conductive cooling to achieve ultra-low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional shielding magnets with multiple coils and narrow axial dimensions are used, then magnetic field cancellation is achieved, but device complexity and mechanical constraints increase
Solution Approach 1:
The shielding function is divided into two independent cylindrical superconducting magnets, each shielding one of the powerful magnets. This segmentation allows each shielding magnet to be designed and operated independently, reducing overall system complexity while maintaining effective magnetic field cancellation.
Solution Approach 2:
The shielding magnets transition from narrow axial dimensions to large axial dimensions with cylindrical geometry. This dimensional change allows the shielding coils to enclose the powerful magnets, providing more effective and uniform magnetic field cancellation while reducing mechanical constraints on coil positioning.
2Object-affected harmful factors
If multiple spatially dispersed coils are used for shielding, then magnetic field cancellation is improved, but ease of manufacture and operational complexity worsen
Solution Approach 1:
Multiple spatially dispersed shielding coils are merged into a single continuous cylindrical superconducting coil. This merging simplifies the manufacturing process by eliminating the need to assemble and precisely position multiple separate coils, while still providing effective magnetic field cancellation through the continuous cylindrical geometry.
3Object-affected harmful factors
If shielding coils are positioned between the magnet and cancellation region, then magnetic field shielding is effective, but device complexity and cooling requirements increase
Solution Approach 1:
The shielding coils are repositioned to enclose the powerful magnets, creating a nested configuration where the shielding magnet contains the magnet being shielded. This nesting provides effective magnetic field containment while allowing both magnets to be cooled from their outer surfaces, simplifying the cooling system design.
4Productivity
If two powerful magnets are positioned in close proximity, then cooling efficiency is improved, but magnetic field interference between magnets worsens
Solution Approach 1:
Cylindrical superconducting shielding magnets are introduced as intermediary elements between the two powerful magnets. These shielding magnets generate opposing magnetic fields that cancel the interference from adjacent magnets, allowing the magnets to be positioned in close proximity for efficient cooling while maintaining magnetic field independence.
5Adaptability or versatility
If one magnet undergoes full magnetic ramp up or down, then operational flexibility is improved, but magnetic field stability for the other magnet worsens
Solution Approach 1:
The shielding magnets are configured to provide preliminary anti-action by generating opposing magnetic fields that counteract the field changes from adjacent magnets. This allows one magnet to undergo full magnetic ramping while the shielding magnet maintains a stable opposing field, protecting the other magnet from field interference and maintaining its operational stability.
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 design allows for a more compact and efficient cooling system with reduced axial forces and increased cooling power, enabling the attainment of temperatures below tens of microKelvin while maintaining high magnetic field homogeneity and independence between magnets.
Implementation Method 1
The material is then thermally decoupled from the dilution refrigerator and the material is allowed to demagnetise. The increased misalignment of the nuclear spins causes an increase in entropy of the material which in turn lowers its temperature further.
Implementation Method 2
a primary shielding magnet for substantially cancelling the magnetic field from the primary magnet at least at a first position between the primary and demagnetisation magnets
Implementation Method 3
the primary shielding magnet comprising a cylindrical superconducting coil having a geometric envelope which encloses the primary magnet
Implementation Method 4
a conductive cooling assembly for coupling in use to a refrigeration system, the conductive cooling assembly being arranged to provide conductive cooling to each of the said magnets
Data Source
AI summary
Cryogenic cooling apparatus is disclosed for cooling a target region using the demagnetization cooling effect. The apparatus has a primary magnet for providing a magnetic field within the target region and a demagnetization magnet arranged to selectively provide conductive cooling to the target region. A primary shielding magnet substantially cancels the magnetic field from the primary magnet at least at a first position between the primary and demagnetization magnets. A demagnetization shielding magnet substantially cancels the magnetic field from the demagnetization magnet at least at the first position between the primary and demagnetization magnets. Each of the primary shielding magnet and demagnetization shielding magnet comprises a cylindrical superconducting coil having a geometric envelope which encloses the primary magnet and demagnetization magnet respectively. A conductive cooling assembly provides conductive cooling to each of the magnets. A cryogenic system including a cryostat, the apparatus and a refrigeration system is also provided.