Fusion Reactor Superconducting Magnet Quench Detection and Hybrid Windings
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Solution Overview
Problem
Current superconducting magnet systems for fusion reactors face limitations in magnetic field strength due to the use of low-temperature superconducting materials and structural materials, leading to increased coil size and cost, and suffer from unreliable power supply and slow, difficult quench detection, which complicates fault identification and repair.
Innovation Solution
A superconducting magnet system utilizing graded hybrid windings with different superconducting materials, an integrated power supply with multi-pulse AC phase shifting, and advanced quench diagnostic modules including resistive voltage, distributed optical fiber, and voiceprint diagnostics for accurate and rapid quench detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If low-temperature superconducting materials (NbTi, Nb3Sn) are used for coil windings, then the magnet system can operate at low cost with established technology, but the magnetic field strength is limited to about 6-16 Tesla
Solution Approach 1:
The patent transitions from low-temperature superconducting materials (operating at 4.2K) to high-temperature superconducting materials (operating at 20-77K), fundamentally changing the operating temperature parameter. This enables the use of materials like REBCO and Bi-2223 that can sustain magnetic fields exceeding 20 Tesla, directly resolving the magnetic field strength limitation while maintaining superconducting operation
Solution Approach 2:
The patent employs composite structural materials including maraging steel (N50, N65) with yield strengths exceeding 2000 MPa at cryogenic temperatures, combined with high-temperature superconducting materials. This composite approach enables the magnet structure to withstand the immense electromagnetic loads at higher magnetic fields while maintaining system reliability
2Temperature
If a single-stage winding structure with uniform superconducting material is adopted, then the manufacturing process is simplified, but the coil size excessively increases and material consumption rises to meet high magnetic field requirements
Solution Approach 1:
The patent implements multi-stage winding structures where different sections of the coil use different superconducting materials optimized for local magnetic field conditions. For example, inner layers may use materials optimized for lower fields while outer layers use materials suited for higher fields, allowing the magnet to achieve 20+ Tesla peak fields with significantly reduced coil volume compared to uniform single-stage designs
Solution Approach 2:
The coil is divided into multiple stages or layers, each with potentially different superconducting materials and winding configurations. This segmentation allows optimization of each section for its specific electromagnetic environment, achieving high overall field strength without proportionally increasing total coil size
3Device complexity
If a three-phase thyristor bridge power supply with parallel connection is used, then the power supply structure is simple, but the redundancy is low and any rectifier bridge failure leads to complete power supply failure
Solution Approach 1:
The power supply is segmented into multiple independent modular units rather than a single monolithic system. Each module can operate independently, and the system can tolerate failures in individual modules while maintaining overall operation. This modular architecture provides inherent redundancy without dramatically increasing overall system complexity
Solution Approach 2:
The power supply design incorporates redundant capacity and fail-safe mechanisms in advance. Backup power supply capacity is built into the system architecture, and protection circuits are pre-configured to detect and isolate faults before they propagate, ensuring continuous operation even when components fail
4Device complexity
If a single resistive voltage-based quench detection method is adopted, then the detection system is simple, but the detection is difficult and slow, especially in strong electromagnetic environments with coupled background noises
Solution Approach 1:
The patent combines multiple quench detection methods into an integrated system: resistive voltage detection, AC voltage detection, and acoustic emission detection. Each method detects different aspects of quench behavior, and their combined use provides cross-validation and significantly improved detection accuracy and speed, overcoming the limitations of any single method in high-noise electromagnetic environments
Solution Approach 2:
Acoustic emission sensors serve as intermediaries to detect mechanical vibrations and pressure waves generated during quench events. These acoustic signals provide an additional detection channel that is less susceptible to electromagnetic interference, enabling more reliable quench detection in strong electromagnetic environments
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
Enhances magnetic field strength, reduces coil size and cost, improves power supply reliability, and enables fast and precise quench detection and localization, ensuring stable operation and efficient fault management.
Implementation Method 1
coil windings of the superconducting magnet for fusion reactors are all made of low-temperature superconducting materials, such as NbTi and Nb3Sn
Implementation Method 2
The superconducting coil is configured to generate a toroidal magnetic field to confine the plasma
Implementation Method 3
perform light scattering and demodulation processing on incident light captured by the distributed sensing optical fiber
Implementation Method 4
the distributed optical fiber diagnostic module comprises a distributed sensing optical fiber
Data Source
AI summary
A superconducting magnet system for fusion reactor includes a superconducting magnet unit, an integrated power supply system and a quench diagnostic system. The superconducting magnet unit includes a superconducting coil module and a cryogenic refrigeration module. The superconducting coil module includes a toroidal field coil, a poloidal field coil and a centric solenoidal magnet module. The integrated power supply system includes a power supply module, a power supply monitoring module, and an alternating current (AC)/direct current (DC) power distribution module connected to the power supply module and the power supply monitoring module. The quench diagnostic system includes a resistive voltage diagnostic module, a distributed optical fiber diagnostic module and a voiceprint diagnostic module.