Retractable Current Lead for Superconducting Magnet
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Solution Overview
Problem
Current lead assemblies in conduction cooled superconducting magnets face challenges in minimizing heat load and achieving good electrical contact at low temperatures in vacuum environments, leading to high resistance and heat load issues.
Innovation Solution
A retractable current lead assembly with a thermal isolation support structure and thermal connector that allows connections to be made at ambient temperature, reducing heat load and improving contact reliability by using a retractable contact and actuator assembly within a vacuum chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If current leads are made to penetrate the vacuum chamber at low temperature for conduction cooling, then cooling efficiency is improved, but contact resistance increases and electrical connection reliability deteriorates
Solution Approach 1:
A thermal isolation support structure serves as an intermediary component between the vacuum chamber wall and the current lead contact. This structure provides thermal isolation to maintain low temperature for cooling while creating a separate thermal environment that allows ambient temperature operation for reliable electrical contact. The support structure mediates between the conflicting temperature requirements of cooling efficiency and contact reliability.
Solution Approach 2:
The current lead assembly is segmented into distinct functional zones: a cold zone within the vacuum chamber for thermal conduction cooling, and a warm zone within the thermal isolation support structure for electrical contact. This segmentation allows each zone to operate at its optimal temperature independently, resolving the contradiction between cooling requirements and contact reliability.
2Strength
If current leads are made rigid for structural stability, then mechanical strength is improved, but compliance decreases making electrical contact difficult
Solution Approach 1:
The current lead system is divided into a rigid support structure that provides mechanical strength and stability, and a flexible contact portion that provides compliance for electrical connection. The rigid thermal isolation support structure maintains structural integrity while the contact elements within it can deform to establish reliable electrical contact.
3Length of moving object
If current leads are made long to reach from power supply to superconducting coils, then electrical connection is achieved, but heat conduction increases causing heat load
Solution Approach 1:
The thermal isolation support structure acts as a thermal intermediary that blocks heat conduction pathways. By providing thermal isolation between the ambient temperature power supply region and the cryogenic superconducting magnet region, it prevents heat from conducting through the current lead support structure, reducing heat load despite the necessary length for electrical connection.
4Adaptability or versatility
If demountable current leads are used for persistent mode operation, then operational flexibility is improved, but connection complexity increases in vacuum chamber
Solution Approach 1:
The thermal isolation support structure serves as a fixed intermediary framework that simplifies demountable connections. By providing pre-positioned contact points and thermal isolation within this fixed structure, the complexity of making and breaking connections in vacuum is reduced, while still enabling persistent mode operation through demountable current leads.
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
Enables the efficient supply of high currents to superconducting magnets while minimizing heat load and maintaining low contact resistance, even in vacuum environments, by establishing connections at ambient temperature and using materials that minimize thermal conduction.
Implementation Method 1
The current contact is supported by a thermal isolation support structure coupled to an inside wall of the vacuum chamber
Implementation Method 2
The thermal connector, coupling the current contact and the magnet lead, is selected to minimize the heat load to the superconducting magnet resulting from the thermal conduction between the retractable contact and the current contact in the thermal isolation support structure
Implementation Method 3
Superconducting magnets conduct electricity with effectively zero resistance as long as the magnets are maintained at a suitably low temperature, which is referred to as a 'superconducting temperature' hereinafter
Implementation Method 4
Cryogenic systems are used to ensure that the superconducting magnets work at the superconducting temperature
Data Source
AI summary
A current lead assembly for minimizing heat load to a conduction cooled superconducting magnet during a ramp operation is provided. The current lead assembly includes a vacuum chamber having a through hole to enable a retractable current lead having a retractable contact to penetrate within the vacuum chamber. A superconducting magnet is arranged inside of the vacuum chamber and includes a magnet lead. A current contact is arranged inside of the vacuum chamber beneath the through-hole and is coupled to the magnet lead via a thermal connector. The current contact is supported by a thermal isolation support structure coupled to an inside wall of the vacuum chamber. An actuator assembly is provided to contact the retractable contact with the current contact, where connection occurs at ambient temperature inside of the thermal isolation support structure.