HTS Field Coil Partial Insulation for Quench Hotspot Mitigation
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Solution Overview
Problem
Existing partially insulated HTS field coils experience uneven quenching due to varying I/IC fractions, leading to localized hotspots and potential damage, particularly in compact designs like spherical tokamaks and proton beam therapy devices, where space and size constraints limit additional HTS tapes or cooling.
Innovation Solution
Incorporate HTS elements in series with the conductive paths of the partially insulating layer to act as current limiters, redistributing current during a quench and mitigating hotspots by increasing resistance where necessary, ensuring even energy dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HTS field coils are designed with varying I/IC fractions to optimize performance, then coil efficiency is improved, but uneven quenching occurs leading to localized hotspots and potential damage
Solution Approach 1:
The patent applies local quality by making the insulating layer properties position-dependent within the coil. Different regions of the coil have insulating layers with different resistivities, allowing current redistribution to be optimized locally. This enables the coil to maintain high efficiency in high-field regions while providing enhanced protection against hotspots in regions more susceptible to quenching, thus resolving the contradiction between productivity and reliability.
2Reliability
If additional HTS tapes or cooling systems are added to mitigate hotspots, then coil reliability is improved, but device size and complexity increase
Solution Approach 1:
The patent changes the electrical parameter (resistivity) of the existing insulating layer to achieve hotspot mitigation. By adjusting the resistivity of the insulating layer material, the system can control current redistribution during quench without adding physical components. This parameter-based solution maintains coil reliability while avoiding increases in device complexity and size.
3Object-affected harmful factors
If the insulating layer resistivity is increased to prevent current sharing, then localized heating is reduced, but current redistribution during quench is limited
Solution Approach 1:
The patent applies local quality by creating spatial variation in insulating layer resistivity. Regions with higher resistivity prevent excessive current sharing and localized heating, while regions with lower resistivity allow beneficial current redistribution during quench. This position-dependent resistivity design simultaneously addresses both the prevention of localized heating and the maintenance of energy dissipation pathways.
Solution Approach 2:
The patent employs composite material structure by combining insulating layer materials with different resistivity characteristics in different coil regions. This composite approach allows the system to leverage the advantages of both high-resistivity materials (hotspot prevention) and low-resistivity materials (current redistribution), achieving a balance between localized heating prevention and energy dissipation.
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 the risk of localized heating and damage by evenly distributing the energy dumped during a quench, maintaining coil integrity and efficiency without significantly increasing thickness.
Implementation Method 1
high temperature superconductor (HTS) field coils
Implementation Method 2
partially insulating layer separating the turns, such that current can be shared between turns via the partially insulating layer
Data Source
AI summary
A high temperature superconducting, HTS, field coil. The HTS field coil comprises a plurality of turns comprising HTS material and metallic stabilizer; and a partially insulating layer separating the turns, such that current can be shared between turns via the partially insulating layer. The partially insulating layer comprises an insulating region, and a plurality of electrically conductive paths through the insulating region, wherein current can be shared between the turns via the electrically conductive paths. Each electrically conductive path comprises an HTS bridge comprising HTS material, wherein the HTS bridge is in series with normally conducting material of the electrically conductive path.