Cryostat Service Neck Venting With Integrated Current Leads
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Solution Overview
Problem
Conventional cryostat access necks face issues such as air contamination, high heat load, and inefficient gas venting during magnet operation and quench processes, leading to helium loss and requiring skilled engineers for controlled de-energization.
Innovation Solution
A cryostat service neck design featuring separate positive and negative current leads, where the neck tube wall acts as one lead and the space between forms a gas path for venting and filling, with collars providing thermal and electrical connections to minimize heat load and pressure differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a removable current lead is used, then access to the magnet terminal is improved, but air contamination risk increases
Solution Approach 1:
The system uses the boil-off gas that would otherwise be wasted to automatically cool the current leads and maintain the cold environment. This self-cooling mechanism eliminates the need for additional refrigeration systems and continuously maintains the cryogenic environment without manual intervention, preventing air contamination while keeping the current lead removable for access.
2Object-affected harmful factors
If fixed current leads are used, then air contamination is reduced, but heat load increases
Solution Approach 1:
The patent changes the thermal parameters of the current leads by using materials and designs optimized for minimal heat conduction. The leads are thermally insulated along their length, and the collar design incorporates thermal barriers. This reduces the heat load from the room-temperature end to the cryogenic end, addressing the energy loss issue while maintaining the fixed structure that prevents air contamination.
3Loss of energy
If multiple radiation baffles are used, then heat load is reduced, but back pressure during quench increases
Solution Approach 1:
The service neck is segmented into multiple functional zones: radiation baffles for thermal protection, a collar for electrical connection and current lead support, and a gas venting path for pressure relief. This segmentation allows each component to perform its specific function optimally - the baffles reduce heat load while the dedicated gas path handles quench pressure without resistance.
4Ease of operation
If the neck is opened to atmosphere, then current lead insertion is simplified, but ice formation risk increases
Solution Approach 1:
The continuous boil-off gas flow creates a self-maintaining cryogenic environment in the service neck. This flowing cold gas actively cools the neck interior, preventing ice formation from atmospheric moisture even when the neck is opened for current lead insertion. The system uses its own operational byproduct (boil-off gas) to protect against the harmful effect.
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 reduces helium loss, lowers heat load, and provides efficient cooling and separate fluid release paths, enhancing operational safety and reducing the need for skilled personnel during magnet operations.
Implementation Method 1
collars providing thermal and electrical connections to minimize heat load
Implementation Method 2
the gas to exit from the cryostat... recondenses the evaporated gases
Data Source
AI summary
The present invention relates to a cryostat having a service neck for access to a superconducting magnet. In many cryogenic applications components, e.g. superconducting coils for magnetic resonance imaging (MRI), superconducting transformers, generators, electronics, are cooled by keeping them in contact with a volume of liquefied, the whole cryogenic assembly being known as a cryostat. In order to operate a superconducting magnet, it must be kept at a temperature below its superconducting transition temperature. A cryostat must provide access to the vessel containing the liquefied helium for the initial cooling of the magnet to its low operating temperature, for periodic refilling of systems where there is a loss of helium, and provide sufficient access whereby to enable operation and maintenance of the magnet. The present invention seeks to provide an access neck to a cryostat such as helium vessel with a minimum heat load and accordingly provides a cryostat assembly, wherein a service neck comprising at least one positive and one negative current lead is arranged such that one of the leads is formed by the neck tube wall and the space between a neck tube wall and the second current lead forms a gas path for venting and/or filling or other services.