Superconducting Wire With Thin Protection Layer For High-Frequency Coils
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Solution Overview
Problem
High-frequency coils used in devices like MRI, NMR, and WPT face limitations in achieving large Q values due to conductor loss, especially when using rare earth-based superconducting wires, as high-frequency currents are concentrated on the surface rather than efficiently flowing through the superconductor layer.
Innovation Solution
A superconducting wire structure is developed with a rare earth-based superconductor layer on the surface of the base material, and a conductive or dielectric protection layer, where the protection layer's thickness is optimized to be 5% or less of the skin depth, and the dielectric tangent is 0.001 or smaller, to minimize conductor loss and enhance Q values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a rare earth-based superconducting wire is used for high-frequency coils, then conductor loss is reduced compared to copper, but the Q value decreases as frequency increases due to surface concentration of high-frequency currents
Solution Approach 1:
The patent changes the physical parameters of the superconducting wire by forming a thin protective layer (5% or less of skin depth) on the superconductor surface. This parameter modification allows high-frequency currents to flow through the superconductor layer rather than being confined to the protective layer, maintaining low conductor loss while preserving the Q value at high frequencies.
Solution Approach 2:
The patent creates a composite structure combining a superconductor layer with a protective layer (either conductive material like silver with controlled thickness, or dielectric material with low tan δ). This composite configuration enables the wire to simultaneously achieve low conductor loss through the superconductor and maintain high Q value by controlling current distribution through the protective layer's electromagnetic properties.
2Reliability
If a protective layer is added to protect the superconductor layer, then the superconductor is protected from environmental damage, but conductor loss increases and Q value decreases
Solution Approach 1:
The patent precisely controls the thickness parameter of the protective layer to be 5% or less of the skin depth at the operating frequency. This parameter optimization ensures the protective layer is thin enough to allow high-frequency currents to penetrate and flow through the superconductor layer, minimizing conductor loss while still providing adequate environmental protection.
Solution Approach 2:
The patent applies different material properties locally: the protective layer uses either conductive material (silver) with carefully controlled thickness or dielectric material with extremely low tan δ (0.001 or smaller). This local quality differentiation allows the protective layer to provide environmental protection while minimizing its negative impact on electrical performance.
3Reliability
If a dielectric protection layer with low dielectric tangent is used, then Q value is maintained, but manufacturing complexity increases
Solution Approach 1:
The patent specifies a quantitative parameter for the dielectric protection layer: dielectric tangent tan δ of 0.001 or smaller. This clear parameter specification simplifies material selection and manufacturing control, enabling manufacturers to choose from known low-loss dielectric materials while achieving the required Q value performance.
Solution Approach 2:
The dielectric protection layer acts as an intermediary between the superconductor and the external environment, providing both protection and electromagnetic performance. By selecting dielectric materials with inherently low tan δ values, the intermediary layer maintains Q value while simplifying the overall design compared to attempting to achieve the same performance without a protective layer.
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 allows high-frequency currents to preferentially flow through the superconductor layer, significantly increasing the Q value of the coil, even in high-frequency bands, thereby improving the performance of devices like MRI, NMR, and WPT.
Implementation Method 1
a superconductor layer formed on each of the respective surfaces of the base material
Implementation Method 2
the thickness of each of the conductive protection layers is 5% or less of the skin depth when a high-frequency current flows through the superconducting wire
Implementation Method 3
the dielectric protection layer is formed using a material having the value of a dielectric tangent (tan δ) of 0.001 or smaller
Data Source
AI summary
A superconducting wire according to the present disclosure includes: a base material; a superconductor layer formed on each of the respective surfaces of the base material; and a conductive protection layer formed on each of the surfaces of the respective superconductor layers. The thickness of each of the conductive protection layers is 5% or less of the skin depth when a high-frequency current flows through the superconducting wire. The material for forming the conductive protection layer may be, for example, silver.