Distributed Heater Network for Superconducting Magnet Quench Protection
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Solution Overview
Problem
Existing quench protection circuits for superconducting magnet systems suffer from low protection reliability, slow response times, unbalanced forces, and stray field expansion due to unequal currents flowing through symmetrical coils, leading to potential structural damage and safety hazards.
Innovation Solution
A quench protection circuit with a distributed heater network where M superconducting coils are connected in series and N heater modules are connected in parallel, with each heater module having m parallel branches of n heaters in series, ensuring symmetric voltage distribution and balanced currents during quenching, thereby improving reliability and response times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If all heaters are connected in series to form a heater network, then the circuit structure is simple, but the protection reliability becomes low because an open circuit anywhere causes complete loss of protection
Solution Approach 1:
The heater network is divided into multiple parallel branches, where each branch contains multiple heaters connected in series. This segmentation allows the system to maintain protection functionality even if some heaters or branches fail, as other branches remain operational. The patent specifically configures the heater network with multiple parallel paths to ensure redundancy and continued protection capability.
2Device complexity
If all heaters are connected in series, then the voltage distribution is simplified, but the response speed becomes slow due to excessively high voltage across coil subsets requiring smaller heater resistance
Solution Approach 1:
The heater network is segmented into multiple parallel branches, which distributes the voltage more effectively across the heater elements. This segmentation allows for optimized heater resistance values that enable faster thermal response during quench events, while maintaining manageable voltage levels across each branch.
Solution Approach 2:
By changing the connection configuration from purely series to parallel branches with series heaters, the electrical parameters (voltage distribution, current paths) are optimized to achieve faster heating response. The patent adjusts the resistance and voltage distribution parameters to improve quench detection and protection speed.
3Reliability
If heater modules are connected in parallel with superconducting coils, then the quench protection coverage is improved, but unbalanced forces and stray field expansion occur due to unequal currents through symmetrical coils
Solution Approach 1:
The patent introduces asymmetry in the connection configuration to achieve symmetry in current distribution. By carefully designing which heater modules connect to which coil subsets, the system compensates for potential current imbalances and maintains force equilibrium in symmetrical coil arrangements during quench events.
Solution Approach 2:
The heater network is designed to maintain equipotential conditions across symmetrical coil subsets during normal operation and quench events. This ensures equal current distribution through symmetrical coils, preventing unbalanced forces and stray field expansion while providing comprehensive quench protection coverage.
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 controls current differences and stray field expansion, enhancing protection reliability and response speed, ensuring balanced forces and preventing structural damage and safety hazards, even if one module is disconnected.
Implementation Method 1
A heater is attached to the surface of each superconducting coil in thermal contact with the superconducting coil. These heaters are connected in series to form a heater network. During the quenching process, the heating power of the heater is low, resulting in a slow quench protection response.
Implementation Method 2
superconducting magnets are smaller in size, have higher current density, consume less energy, and exhibit greater magnetic field strength compared with resistive magnets. During normal ramp-up, ramp-down or steady-state operation, the superconducting magnet is in a superconducting state, that is, a resistance-free state.
Implementation Method 3
A low temperature superconducting switch 103 and the current leads 104 are connected in parallel. The threshold voltage of the first diode pack 102 is higher than the maximum excitation voltage at both ends of the magnet for protecting the low temperature superconducting switch 103.
Data Source
AI summary
The disclosure belongs to the field of quench protection of a superconducting magnet system and specifically relates to a quench protection circuit for a superconducting magnet system based on a distributed heater network including M superconducting coils connected in series and a heater network formed by N heater modules, where M>N and N≤3. Different heater modules are connected in parallel with different superconducting coil subsets, and all superconducting coil subsets have spatial symmetry. Each heater module has m parallel branches, and each parallel branch has n heaters connected in parallel, where m≥1, n≥1, and when N=1, m>1. Each heater in the heater network is thermally coupled to one superconducting coil among the M superconducting coils, and each superconducting coil is thermally coupled to at least one heater in each heater module.