MRI Static Magnet Winding Frame for Eddy-Current Heat Isolation
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Solution Overview
Problem
The direct transmission of heat due to eddy currents caused by gradient-coil induced heating (GCIH) to the superconducting coil increases the probability of quench in MRI apparatuses, particularly in cylindrical MRI systems where patients are exposed to noise and movement during imaging, leading to artifacts and difficulty in imaging patients with curved spines.
Innovation Solution
The implementation of a heat-generation suppression shield with a two-layer structure in the winding frame, comprising a surface layer where eddy currents flow and an inner layer where they do not, effectively reducing heat transmission to the superconducting coil, thereby preventing quench.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the winding frame supports the superconducting coil with a gap of only a few millimeters, then the structural stability is improved, but the heat due to eddy current is directly transmitted to the superconducting coil, increasing the probability of quench
Solution Approach 1:
A heat-generation suppression shield is introduced as an intermediary component between the gradient coil and the superconducting coil. This shield intercepts eddy currents generated in the gradient coil, preventing heat from being directly transmitted to the superconducting coil, thus resolving the contradiction between structural stability and quench probability
Solution Approach 2:
The harmful heat generation function is extracted from the gradient coil system by introducing a separate heat-generation suppression shield. This shield specifically targets and removes the eddy current heat generation problem, allowing the gradient coil to maintain its structural role while eliminating the thermal hazard to the superconducting coil
2Reliability
If a heat-generation suppression shield is added to reduce heat transmission, then the quench probability is reduced, but the device complexity increases
Solution Approach 1:
The heat-generation suppression shield is designed to serve multiple functions: it suppresses eddy current heat generation, provides structural support, and maintains the spatial relationship between components. By combining multiple functions into a single component, the overall device complexity is minimized while achieving the reliability improvement
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 suppression shield significantly reduces heat generation in the superconducting coil, minimizing the risk of quench and enhancing imaging stability, especially in planar-open-magnet MRI systems, allowing for improved patient positioning and reduced artifacts.
Implementation Method 1
the surface layer is configured as a layer where an eddy current generated in the winding frame flows
Implementation Method 2
the inner layer is configured as a layer where an eddy current does not almost flow
Implementation Method 3
effectively reducing heat transmission to the superconducting coil, thereby preventing quench
Data Source
AI summary
A static magnetic field magnet according to any of embodiments includes: a vacuum vessel; a radiation shield provided inside the vacuum vessel; a superconducting coil provided inside the radiation shield, the superconducting coil generating a static magnetic field; and a winding frame supporting the superconducting coil and including a heat-generation suppression shield having a surface layer on a gradient coil side and an inner layer on the superconducting coil side. In the static magnetic field magnet, the surface layer and the inner layer are structurally or functionally separated from each other, the surface layer is configured as a layer where an eddy current generated in the winding frame flows, and the inner layer is configured as a layer where an eddy current does not almost flow.