Inductive Quench for Superconducting Magnet Protection
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Solution Overview
Problem
High-performance superconducting magnets face challenges in quickly and efficiently dissipating stored magnetic energy to prevent damage from localized heating during a quench, especially due to high voltages and potential mechanical stresses from temperature differentials, requiring innovative heating methods that minimize reactive power usage.
Innovation Solution
A quench system utilizing a DC superconducting coil and an AC coil system with orthogonal magnetic fields to induce AC losses, reducing mutual inductance and reactive power requirements, and employing thermal blankets to facilitate heat dissipation without direct contact, allowing for efficient heating of a substantial fraction of the conductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If local Joule heaters are used to initiate quench, then the superconducting-to-normal transition can be achieved, but the heating is localized and results in large temperature differentials and mechanical stresses
Solution Approach 1:
The patent divides the heating function into multiple AC coil segments positioned around the magnet winding. Each coil generates AC magnetic fields that induce heating at different locations, collectively achieving uniform heating across the entire winding volume rather than localized heating from single Joule heaters
Solution Approach 2:
The patent employs AC magnetic fields at specific frequencies to induce AC losses (hysteresis, eddy currents) in the superconducting winding. This oscillating electromagnetic field approach creates distributed heating throughout the winding volume, transforming the heating mechanism from localized resistive heating to volumetric electromagnetic heating
2Temperature
If AC magnetic fields are used to heat the coil, then distributed heating is achieved, but reactive power requirements increase
Solution Approach 1:
The patent optimizes the AC coil configuration and operating parameters to concentrate AC losses specifically within the superconducting winding where heating is needed. By tuning the AC field frequency and amplitude, the system maximizes hysteresis and eddy current losses in the superconductor while minimizing reactive power consumption in the AC coil system itself
Solution Approach 2:
The patent utilizes frequency-dependent AC loss mechanisms in superconductors. By operating at frequencies where hysteresis and coupling losses are maximized, the system achieves efficient heating with reduced reactive power requirements. The AC field parameters are optimized to exploit the superconductor's electromagnetic properties at specific frequencies
3Speed
If high voltage is used to quickly discharge the magnet, then energy removal speed increases, but the risk of damage and equipment stress increases
Solution Approach 1:
The patent initiates quench by applying AC magnetic fields to heat the superconducting winding before rapid discharge. This preliminary heating action creates normal conducting zones that provide natural current paths, allowing subsequent energy discharge to occur at lower voltages and reduced stress on the magnet and external circuitry
Solution Approach 2:
The patent converts the potentially harmful effect of AC magnetic fields (which can induce large reactive powers and voltages) into a beneficial heating mechanism. By carefully controlling the AC field parameters and coil configuration, the system generates distributed heat that initiates quench, thereby enabling safe and controlled energy discharge without requiring extreme voltages
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 approach effectively reduces the reactive power needed to initiate a quench across a large fraction of the superconducting coil, minimizing mechanical stresses and preventing damage by achieving uniform temperature distribution and reducing peak temperatures during energy dissipation.
Implementation Method 1
The AC magnetic fields heat the DC coil to cause a superconducting-to-normal transition over a substantial fraction of the DC superconducting coil
Implementation Method 2
an AC coil system located in proximity to the DC superconducting coil to generate AC magnetic fields
Implementation Method 3
the DC superconducting coil and the AC coil system are arranged so that the mutual inductance between the DC superconducting coil and the AC coil is close to zero. The magnetic fields of the DC superconducting coil and AC coil system may be orthogonal to one another to provide the low mutual inductance
Implementation Method 4
employing thermal blankets to facilitate heat dissipation without direct contact
Data Source
AI summary
A coil system for inductively heating a superconducting magnet in order to provide an internal energy dump by uniformly quenching a high performance superconducting magnet. The quench-inducing system uses AC magnetic fields that require negligible reactive power. The system is especially suited for inducing a relatively uniform quench in dry superconducting magnets.