HTS Magnet Partial Insulation with Diagnostic Pickup Coils
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Solution Overview
Problem
High temperature superconducting (HTS) magnets face challenges in detecting quench events quickly enough to prevent damage, as the rate of transverse propagation of normal zones in partially insulated coils can lead to rapid temperature rises and potential damage, especially in applications like tokamak fusion reactors and proton beam therapy devices.
Innovation Solution
A partially insulating layer with linking and pickup tracks is introduced, where the linking tracks provide an electrical path between HTS coil turns and the pickup tracks are inductively coupled to measure current changes, allowing for early detection of current sharing and potential quench events through a current monitor, thereby extending the time for countermeasure activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If partial insulation is used in HTS magnet coils, then the rate of transverse propagation of normal zones is reduced, but the time available for quench detection and countermeasure activation is insufficient
Solution Approach 1:
A pickup coil is introduced as an intermediary sensing element that inductively couples to the HTS cable. This mediator detects magnetic field changes caused by current redistribution during quench events, enabling indirect but reliable detection without direct electrical contact with the HTS cable, thus maintaining insulation integrity while improving detection capability
Solution Approach 2:
The system implements feedback by continuously monitoring the voltage signal from the pickup coil and comparing it against threshold values. When the detected signal exceeds the threshold, indicating current sharing between HTS and copper stabilizer, the system triggers quench protection countermeasures, creating a closed-loop detection and response system
2Reliability
If insulation resistance between turns is increased, then current sharing is reduced, but detection of current sharing becomes more difficult
Solution Approach 1:
The invention replaces direct electrical measurement methods with inductive sensing. Instead of attempting to measure small leakage currents directly through high-resistance insulation paths, the pickup coil detects magnetic field changes resulting from current redistribution, substituting a magnetic sensing approach for direct electrical measurement
3Reliability
If faster quench detection is implemented, then damage prevention is improved, but system complexity increases
Solution Approach 1:
The pickup coil leverages the existing magnetic field generated by the HTS cable current itself for detection purposes. The system uses its own operational magnetic field as the sensing signal, requiring no external excitation source or additional power consumption, thus reducing system complexity while enabling fast detection
Solution Approach 2:
The pickup coil serves multiple functions: it detects quench events, monitors current distribution, and provides diagnostic information about magnet operation. This multi-functionality reduces the need for separate sensing systems, thereby limiting the increase in overall system complexity
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 enables precise detection of current sharing and imminent quenches, providing an advanced warning system to prevent damage to HTS magnets by facilitating quicker energy dumping and reducing the risk of overheating.
Implementation Method 1
Each pickup track is electrically conductive and is inductively coupled to a respective linking track
Data Source
Figure 1~2B
Figure 2C~2E
Figure 3~4A
AI summary
A partially insulating layer for use in an HTS magnet coil. The partially insulating layer comprises an insulating body 401 having within it a set of linking tracks and a set of pickup tracks. Each linking track is electrically conductive and is electrically connected to first and second surfaces of the partially insulating layer, in order to provide an electrical path between said first and second surfaces. Each pickup track is electrically conductive and is inductively coupled to a respective linking track, and electrically isolated from the first and second surfaces. Each of the pickup tracks is configured for connection to a current measuring device in order to measure a current induced in the pickup track by a change in current flowing in the respective linking track.