Superconducting Gradient Coil Heat Conduction Assemblage
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Solution Overview
Problem
AC superconducting coils generate significant heat due to time-varying gradient magnetic field losses, leading to temperature rises and loss of superconductivity if not properly managed, and also pose challenges with detrimental coupling with nearby instruments.
Innovation Solution
A system incorporating superconductive conductors with a heat conduction assemblage using composite bobbins and thermally conductive materials like sapphire or Litz wire, in conjunction with mechanical cryocoolers, to efficiently conduct heat away from the coils and maintain them in a superconducting state, while also employing shielding coils to mitigate interference with nearby instruments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If AC superconducting coils are used to generate time-varying gradient magnetic fields, then high magnetic gradient strength is achieved, but significant heat is generated due to AC losses
Solution Approach 1:
The patent applies this principle by capturing the heat generated from AC losses in superconducting coils and redirecting it to pre-cool the liquid nitrogen before it contacts the superconducting coils. The harmful heat that would otherwise raise coil temperature is converted into a beneficial cooling resource, extending the cooling time and enabling longer pulse sequences while maintaining superconductivity.
Solution Approach 2:
The system pre-cools the liquid nitrogen using the heat from AC losses before the nitrogen reaches the superconducting coils. This preliminary cooling action ensures that the coolant is already at an optimal temperature when it contacts the coils, improving cooling efficiency and allowing extended operation above the traditional 77K temperature threshold.
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 system effectively generates high-strength time-varying gradient magnetic fields while maintaining the superconducting state of the coils and reducing heat-related issues, enabling stable operation and minimizing interference with other instruments.
Implementation Method 1
Heat generated in association with the time-varying gradient magnetic field is capable of being conducted through the assemblage and away from the wires to achieve a steady-state system temperature below TC
Implementation Method 2
Superconducting wires transport electric current without resistance. A superconducting coil or magnet may be wound with unitary wire or with a cable containing superconducting wires
Implementation Method 3
achieve a steady-state system temperature below TC and thereby maintaining the conductors in a superconducting state
Data Source
AI summary
High magnetic field gradient strength superconducting coil systems for use in medical applications are provided. Systems capable of providing time-varying gradient magnetic field strength greater than 50 mT/m, over a spherical volume with a diameter greater than 20 centimeters include superconducting gradient coils and a heat conduction assemblage in physical contact with each coil.