AC Current Induced Quench Protection for Superconducting Magnets
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Solution Overview
Problem
Conventional quench protection systems for superconducting magnets are inadequate for efficiently quenching large portions of the magnet within a short time, particularly in high-energy applications with efficient helium cooling and higher temperature margins, as they rely on inefficient thermal diffusion and can lead to electrical breakdowns and require costly replacements.
Innovation Solution
An apparatus and method that initiates a transition from the superconducting state to a normal-conducting state by providing an alternating current of predetermined strength and frequency in response to a quench signal, using an LC-circuitry formed by capacitors and coil portions to generate AC current, which induces inter-filament and inter-strand coupling losses for rapid heating, without relying on quench propagation through insulation layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If quench heaters are used to enhance quench propagation, then the normal zone propagation is improved, but the quenching efficiency is reduced due to reliance on inefficient thermal diffusion across insulation layers
Solution Approach 1:
The patent replaces the thermal diffusion mechanism (heat conduction through insulation layers) with an electromagnetic mechanism (AC current induction). By applying an alternating current to a quenching coil, magnetic flux changes induce eddy currents in the superconductor, which generate heat directly within the superconducting material itself, bypassing the need for thermal diffusion across insulation barriers.
Solution Approach 2:
The patent employs periodic alternating current applied to the quenching coil to induce continuous oscillating magnetic flux. This periodic action generates sustained eddy currents and heating within the superconductor, enabling rapid and uniform quench propagation throughout the magnet coil, particularly effective in high-field regions and inner layers where conventional methods fail.
2Reliability
If conventional quench protection systems are used, then quench detection is achieved, but fast and global quench initiation is not achieved, particularly in high-energy applications with efficient helium cooling
Solution Approach 1:
The patent replaces slow thermal diffusion-based quench initiation with rapid electromagnetic induction. The AC current applied to the quenching coil generates time-varying magnetic flux that directly induces eddy currents and heat within the superconductor, achieving quench initiation in milliseconds rather than seconds, which is critical for high-energy magnets with efficient cooling.
Solution Approach 2:
The patent changes the physical state and parameters of the superconductor by inducing eddy currents through AC magnetic fields. This causes rapid temperature increase within the superconducting material, changing its state from superconducting to normal conducting, and this parameter change propagates quickly throughout the magnet coil.
3Temperature
If AC current is applied to induce quenching, then rapid heating and quench initiation is achieved, but inter-filament and inter-strand coupling losses must be managed
Solution Approach 1:
The patent converts the previously problematic inter-filament and inter-strand coupling losses into a beneficial heating mechanism. By applying AC current to the quenching coil, these coupling losses generate eddy currents that produce heat directly within the superconducting filaments and strands, enabling rapid and uniform quench propagation throughout the magnet coil, particularly in high-field regions and inner layers.
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 enables fast and global quench initiation, reduces hotspot temperatures, and is suitable for inner layers and high-field regions, providing efficient energy distribution and lower voltage requirements, making it a robust backup solution for conventional quench heaters.
Implementation Method 1
providing an alternating current of a predetermined strength and frequency to the at least part of the superconductor, wherein the alternating current induces inter-filament and inter-strand coupling losses
Implementation Method 2
the normal-conducting portion of the coil heats up due to localized Joule heating
Data Source
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AI summary
An apparatus (100) for quenching at least part (110) of a superconductor in a superconducting state in reply to a quench signal to initiate a transition from the superconducting state into a normal-conducting state comprises: means (120) for providing an alternating (AC) current of a predetermined strength and/or predetermined frequency to the at least part (110) of the superconductor, wherein the means (120) for providing the AC current comprises a control terminal (130) configured to receive the quench signal. The means (120) for providing the AC current is configured to be activated in response of receiving the quench signal at the control terminal (130) so that the AC current flows through the at least part (110) of the superconductor, wherein the predetermined strength and/or the predetermined frequency is selected such that the transition from the superconducting state into a normal- conducting state is triggered.