Segmented Radiation Shield Structure for Superconducting Magnets
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Solution Overview
Problem
Divided radiation shields in superconducting magnet devices face temperature differences due to varying heat transfer paths, leading to increased radiant heat input to the superconducting coil, which can cause deformation or damage from induced Lorentz forces during magnetic field fluctuations.
Innovation Solution
A radiation shield structure with divided shield pieces connected by a high thermal conductivity thermal bridge member and interposed resistance layers, which reduces eddy currents and maintains uniform temperature distribution while preventing heat input to the superconducting coil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the radiation shield is divided into multiple shield pieces to reduce eddy currents, then eddy currents and Lorentz forces are reduced, but temperature differences occur between shield portions leading to increased radiant heat input
Solution Approach 1:
The radiation shield is divided into multiple shield pieces to reduce eddy currents and Lorentz forces. Each shield piece is electrically isolated from others, preventing large eddy currents during magnetic field fluctuations such as quenching events.
Solution Approach 2:
Thermal bridge members are introduced as intermediary components to thermally connect the divided shield pieces. These thermal bridges restore thermal equilibrium between shield portions without creating electrical conductivity paths that would generate eddy currents.
2Temperature
If the radiation shield is made of thin plate metallic material with good thermal conductivity, then radiant heat input is reduced, but eddy currents are induced by magnetic field fluctuations causing large Lorentz forces
Solution Approach 1:
The continuous metallic radiation shield is segmented into multiple divided shield pieces. This segmentation maintains the thermal conductivity benefits of metallic materials for reducing radiant heat input while eliminating the electrical conductivity path that causes harmful eddy currents and Lorentz forces.
Solution Approach 2:
Different regions of the radiation shield structure have different electrical properties. The shield pieces themselves maintain high thermal conductivity for heat rejection, while the gaps between pieces and the thermal bridge members provide electrical isolation to prevent eddy currents.
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 solution effectively reduces eddy currents and Lorentz forces, minimizing the risk of radiation shield deformation and ensuring uniform cooling, thus maintaining the integrity of the superconducting magnet device.
Implementation Method 1
a thermal bridge member that thermally connects the plurality of divided shield pieces to each other and is formed of a high thermal conductivity metal having a higher thermal conductivity than stainless steel
Implementation Method 2
a resistance layer that is interposed between the thermal bridge member and the divided shield pieces and has a higher electrical resistivity than the thermal bridge member
Implementation Method 3
The radiation shield is cooled to a cryogenic temperature higher than a temperature of the superconducting coil in order to prevent input heat due to radiation from the vacuum container to the superconducting coil
Implementation Method 4
a superconducting coil that is cooled to a cryogenic temperature in the vacuum container
Implementation Method 5
an eddy current is induced in the radiation shield by a fluctuation in acting magnetic field
Implementation Method 6
a large Lorentz force is generated due to interaction between the magnetic field and the eddy current
Data Source
AI summary
A superconducting magnet device includes a superconducting coil; a radiation shield including a plurality of divided shield pieces disposed to surround the superconducting coil; a thermal bridge member that thermally connects the plurality of divided shield pieces to each other and is formed of a high thermal conductivity metal having a higher thermal conductivity than stainless steel; and a resistance layer that is interposed between the thermal bridge member and the divided shield pieces and has a higher electrical resistivity than the thermal bridge member.