HTS Field Coil Insulation for Hotspot Energy Dissipation
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Solution Overview
Problem
High temperature superconductor (HTS) field coils face challenges in managing hotspots due to fault conditions such as cooling failures and radiation-induced degradation, leading to potential thermal runaway and damage, with existing solutions either failing to rapidly dissipate energy or compromising on turn-to-turn resistance for rapid energization/de-energization.
Innovation Solution
The HTS field coil design incorporates a layer of insulator material with varying resistivity and electrical conductor elements that heat up in response to voltage differences, rapidly decreasing turn-to-turn resistance and allowing current to bypass affected turns, thereby dissipating energy quickly and reducing the risk of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a layer of insulator material is used to separate turns in an HTS field coil, then turn-to-turn resistance is increased for electrical isolation, but energy dissipation capability during hotspot events is reduced
Solution Approach 1:
The insulator material's resistivity is made temperature-dependent, transitioning from high resistivity at operating temperature to low resistivity during hotspot events. This parameter change allows the material to provide electrical isolation during normal operation while enabling energy dissipation when needed.
Solution Approach 2:
The insulator material dynamically changes its electrical properties based on temperature conditions. During normal operation, it maintains high resistivity for isolation, but during hotspot events, it transitions to a conductive state to facilitate energy dissipation, making the system adaptive to different operational states.
2Speed
If turn-to-turn resistance is reduced for rapid energization and de-energization, then electrical isolation between turns is compromised, but energy can be dissipated more quickly during faults
Solution Approach 1:
The insulator material exhibits parameter changes with temperature, transitioning from high resistivity at low temperatures to low resistivity at elevated temperatures. This enables rapid energy dissipation during faults while maintaining electrical isolation during normal operation.
Solution Approach 2:
The system dynamically adjusts its electrical characteristics through temperature-dependent resistivity changes in the insulator material, providing electrical isolation during normal operation and facilitating rapid energy dissipation during hotspot events.
3Use of energy by moving object
If HTS field coils are designed for high energy storage, then the impact of hotspot formation and thermal runaway increases, but the utility and efficiency of the magnet system is improved
Solution Approach 1:
The temperature-dependent resistivity of the insulator material converts the harmful thermal runaway process into a beneficial energy dissipation mechanism. When hotspots form, the insulator transitions to a conductive state, facilitating controlled energy dissipation that protects the high-energy magnet system.
Solution Approach 2:
The insulator material is pre-configured with temperature-dependent resistivity characteristics that automatically activate during hotspot events. This beforehand prepared property provides protective cushioning against thermal runaway in high-energy magnet systems without compromising normal operation.
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 design effectively mitigates hotspot formation by rapidly increasing the insulator material's temperature, reducing turn-to-turn resistance, and efficiently dissipating magnetic energy, thus preventing damage to the HTS material and allowing for safe operation of large, high-energy HTS magnets.
Implementation Method 1
a layer of insulator material having a first resistivity at a temperature less than a generation temperature of the HTS material and a lower, second resistivity at a second temperature greater than the generation temperature of the HTS material
Implementation Method 2
electrical current is driven through the one or more electrical conductor elements to heat the layer of insulator material
Implementation Method 3
a high temperature superconductor, HTS, field coil having turns comprising HTS material wound about an axis of the coil
Data Source
AI summary
A high temperature superconductor, HTS, field coil having turns comprising HTS material wound about an axis of the coil. The turns are separated from one another along a direction perpendicular to the axis by a layer of insulator material having a first resistivity at a temperature less than a generation temperature of the HTS material and a lower, second resistivity at a second temperature greater than the generation temperature of the HTS material. The HTS field coil further comprises one or more electrical conductor elements arranged to provide one or more electrically conductive pathways extending from one turn to an adjacent turn and through the layer of insulator material. In response to a voltage difference generated across the one or more electrically conductive pathways, electrical current is driven through the one or more electrical conductor elements to heat the layer of insulator material.