Fixed Ramp Lead Assembly for Quench-Limiting Cryogenic Energization
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Solution Overview
Problem
Ramp leads in superconducting MRI machines cause parasitic heat leaks, leading to temperature increases and potential quench events, especially in systems with limited cryogen supply, which can result in prolonged downtime.
Innovation Solution
A fixed ramp lead assembly with a non-conductive support, a metal rod, and a thermal storage device is used to minimize static heat load and store heat during energization, limiting temperature rise and reducing heat transfer to the thermal anchor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed ramp lead assembly is used to energize superconducting magnets, then ease of operation is improved, but heat transfer to the cryogenic system increases causing temperature rise and potential quench events
Solution Approach 1:
The ramp lead assembly is segmented into multiple thermal zones with intermediate thermal barriers. The assembly includes a room-temperature section, an intermediate temperature section with thermal barriers, and a cryogenic section. This segmentation allows the lead to traverse temperature gradients while minimizing heat transfer to the superconducting magnet, resolving the contradiction between maintaining operational simplicity and controlling temperature rise.
Solution Approach 2:
Thermal barrier elements and intermediate temperature stages act as mediators between the room-temperature control system and the cryogenic superconducting magnet. These intermediate elements absorb and buffer heat transfer, allowing the fixed ramp lead to remain in place without directly transmitting excessive heat to the superconducting components, thus maintaining both ease of operation and temperature control.
2Loss of energy
If ramp leads are completely removed after use to eliminate parasitic heat leak, then heat transfer is reduced, but device complexity increases due to moving parts
Solution Approach 1:
The ramp lead assembly is divided into removable cryogenic-section components and permanent room-temperature support structures. After use, only the cryogenic-section elements need to be removed while the support structures remain in place. This segmentation eliminates the need for complete assembly removal, reducing device complexity while still eliminating parasitic heat leaks from the cryogenic components.
Solution Approach 2:
The heat-conducting cryogenic-section elements are extracted and removed after energization, while the non-conducting or low-conductivity support structures remain permanently installed. This selective extraction eliminates the parasitic heat leak path through the ramp lead while avoiding the complexity of removing entire assemblies with moving parts.
3Temperature
If thermal storage device is added to limit temperature rise during energization, then temperature control is improved, but device complexity increases
Solution Approach 1:
The thermal storage function is merged with existing structural components of the ramp lead assembly. Thermal mass elements are integrated into the support structures and thermal barrier elements, combining mechanical support and thermal management functions into unified components. This merging provides temperature control during energization while minimizing additional device complexity.
Solution Approach 2:
Existing ramp lead assembly components are designed to serve multiple functions: structural support, thermal conduction pathways, and thermal storage. The support structures and thermal barriers are engineered to provide both mechanical integrity and thermal management, including temperature limiting during energization. This multi-functionality achieves temperature control without adding separate dedicated thermal storage devices.
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 provides a robust, low-cost configuration that maintains temperature control, prevents quench events, and enables automatic ramping of superconducting magnets, even with limited cryogen, ensuring continuous operation and reducing heat transfer during energization.
Implementation Method 1
A thermal storage device can be coupled to the metal rod between the first end and the second end. The thermal storage device can be configured to store heat during energization of the superconducting magnet, to limit heat transfer along the metal rod to the second end during the energization of the superconducting magnet
Implementation Method 2
The ramp lead assembly also includes a metal rod configured to minimize static heat load, wherein the metal rod is disposed on the non-conductive support and extends between the first end and the second end
Implementation Method 3
A high temperature superconductor portion of the high temperature superconductor power lead is disposed between the second end of the metal rod and the superconducting switch
Data Source
AI summary
A superconducting machine system includes a superconducting electrical machine and a cryogenic vessel encompassing the superconducting electrical machine. The superconducting machine system includes a ramp lead assembly disposed within a vacuum vessel wall and having a first end and a second end. The first end of the ramp lead assembly is coupled in a fixed manner to the vacuum vessel wall and the second end is coupled to a high temperature superconductor power lead coupled to the superconducting switch. The ramp lead assembly includes a non-conductive support and a metal rod. The ramp lead assembly includes a thermal storage device coupled to the metal rod. The thermal storage device is configured to store heat, to limit heat transfer along the metal rod, and to limit an increase in temperature along the ramp lead assembly during the energization of the superconducting electrical machine.