Superconducting Quick Switch with Partial Current Path
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Solution Overview
Problem
Conventional superconducting switches face challenges in balancing transition time and heat output to minimize cryogen boil-off, while requiring high resistance and stability to maintain magnetic fields effectively.
Innovation Solution
A non-inductive superconducting current path switch is thermally coupled to a heater element, allowing it to carry only a portion of the current needed for the magnet, transitioning quickly between superconducting and resistive states to reduce boil-off and maintain magnetic fields efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switch is designed to carry full magnet current, then it can maintain persistent mode, but transition time increases and heat output increases causing excessive cryogen boil-off
Solution Approach 1:
The switch is designed to carry only a portion (e.g., 1-10%) of the full magnet current during persistent mode, rather than the complete current. This partial current carrying capability reduces the heat generation and cryogen boil-off while still providing effective field control, accepting that the switch cannot carry 100% of magnet current in persistent mode
2Loss of energy
If the switch resistance is increased to reduce current during ramp-up, then heat generation decreases, but the switch becomes less effective at controlling field ramping
Solution Approach 1:
The switch resistance is optimized to a specific range (e.g., 0.1-10 ohms) that balances two requirements: high enough to limit current and heat during ramp-up, but low enough to maintain effectiveness in controlling field ramping. The resistance parameter is specifically tuned to achieve both objectives simultaneously
3Productivity
If the switch is designed for fast transition, then productivity improves, but stability decreases causing unwanted state changes
Solution Approach 1:
A heater element is incorporated that can be activated before the desired transition to preheat the switch, initiating the transition process in advance. This preliminary heating action enables faster and more controlled transitions between superconducting and normal states while maintaining stability during operation
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 design achieves faster charge times and reduced cryogen boil-off by minimizing transition time and heat generation, while maintaining stable magnetic fields with lower resistance requirements and reduced energy consumption.
Implementation Method 1
One known thermal persistent switch includes a resistive wire wound about the superconducting wire. Normalization of the superconducting material of the switch is effected by applying electrical current to the resistive wire, thereby heating the superconducting material to above its critical temperature.
Implementation Method 2
a magnet can be made superconducting by placing it in an extremely cold environment, such as by enclosing it in a cryostat or pressure vessel containing liquid helium or other cryogen. The extreme cold reduces the resistance in the magnet coils to negligible levels.
Data Source
AI summary
A magnet system for generating a magnetic field may include a superconducting magnet, a switch, and a heater element thermally coupled to the switch. The superconducting magnet is structured to generate magnetic fields, and the switch includes a non-inductive superconducting current carrying path connected in parallel to the superconducting magnet. In general, the switch is structured to only carry a level of current that is a portion of the current required to obtain a full field by the superconducting magnet.