Superconducting MRI Magnet Coil Layout Without Joint Resistance
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Solution Overview
Problem
Conventional superconducting magnets in MRI systems have high resistance at joints, which limits the duration of the persistent current mode and the strength of the static magnetic field, especially in magnets with smaller inductance, due to the finite resistance of solder layers and oxide layers at these joints.
Innovation Solution
The design eliminates or minimizes the use of superconducting joints by forming a continuous superconducting wire with opposite current directions in first and second coil segments, connected by intermediate wiring, allowing current to flow without interruption and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If superconducting joints are used to connect superconducting coils, then the coils can be assembled at different positions with different diameters and turns, but the joint resistance increases the overall resistance and limits the persistent current mode duration
Solution Approach 1:
The patent merges the superconducting wire into a continuous structure where the first and second coil segments are formed from a single superconducting wire without joints. This eliminates the solder layer and oxide layer resistance issues inherent in conventional jointed connections, thereby extending the persistent current mode duration while maintaining the required coil configuration flexibility through continuous wire routing.
Solution Approach 2:
The patent ensures continuous superconducting current flow by eliminating discontinuous joints between coil segments. The continuous superconducting wire allows persistent current to flow uninterrupted through both coil segments, maintaining the superconducting state and extending the duration of the persistent current mode without the resistance losses that would occur at joint interfaces.
2Ease of manufacture
If superconducting joints with solder layers are used, then coil assembly is feasible, but the solder layer and oxide layer create finite resistance that dominates the total resistance in small inductance magnets
Solution Approach 1:
The patent combines the manufacturing approach by forming both coil segments from a single continuous superconducting wire, eliminating the need for separate joint assembly operations. This merging of the wire structure removes the solder layer and oxide layer that cause resistance losses, achieving both manufacturing feasibility and minimal energy loss simultaneously.
3Device complexity
If conventional superconducting joints are used, then the magnet can be constructed with multiple coils, but the finite joint resistance reduces the time constant of magnetic field attenuation
Solution Approach 1:
The patent merges multiple coil segments into a continuous superconducting structure, eliminating the joint resistances that would otherwise dominate the total resistance in multi-coil configurations. This merging approach maintains the beneficial multi-segment geometry while removing the harmful resistance effects, thereby extending the time constant of magnetic field attenuation.
Solution Approach 2:
The patent ensures continuous superconducting action throughout the entire coil structure by eliminating discontinuous joints. This continuity maintains the superconducting state across what would otherwise be joint interfaces, preserving the persistent current mode and extending the time constant of magnetic field attenuation in multi-segment coil configurations.
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 significantly reduces the resistance at connections, extending the duration of the persistent current mode and enhancing the stability and flexibility of the static magnetic field distribution.
Implementation Method 1
a superconducting coil is cooled down to an extremely low temperature by, for example, liquid helium
Implementation Method 2
intermediate wiring provided between the first coil segment and the second coil segment and configured to connect the first coil segment and the second coil segment without disconnection
Implementation Method 3
a first coil segment formed of a superconducting wire through which a current flows in a forward direction, and a second coil segment formed of the superconducting wire through which a current flows in a direction opposite to the forward direction
Data Source
AI summary
In one embodiment, a superconducting magnet includes: at least one set of coil segment including a first coil segment formed of a superconducting wire through which an electric current flows in a forward direction, and a second coil segment formed of the superconducting wire through which an electric current flows in a direction opposite to the forward direction; and at least one intermediate wiring provided between the first coil segment and the second coil segment and configured to connect the first coil segment and the second coil segment without disconnection and change directions of electric currents such that that the electric current flows through the first coil segment in the forward direction and the electric current flows through the second coil segment in a direction opposite to the forward direction.