Thermal Gradient Structure for Pressurized Liquid Helium Cooling
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Solution Overview
Problem
Cryogenic systems operating at temperatures near absolute zero face challenges in maintaining helium gas at atmospheric pressure while achieving temperatures below the boiling point of liquid helium, which is essential for stable superconducting operations but poses risks due to potential air ingress and pressure issues.
Innovation Solution
The introduction of a thermal gradient enhancement structure within the cryogenic vessel, made from thermally insulating materials, creates temperature gradients and allows for the operation of cryogenic liquids below their boiling point while maintaining positive pressure, using features like long open channels or movable flaps to manage flash boiling during quench events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid helium is cooled below its boiling point of 4.2 degrees Kelvin to achieve lower operating temperatures for superconducting devices, then the temperature is improved, but the pressure drops below atmospheric pressure which risks air ingress and safety issues
Solution Approach 1:
The patent applies parameter changes by introducing a thermal gradient enhancement structure that fundamentally alters the temperature distribution parameters within the liquid helium. The structure creates distinct thermal zones (first region with temperature T1, second region with temperature T2 where T1 > T2) allowing the system to operate at lower average temperatures while maintaining atmospheric pressure through controlled thermal differentiation rather than uniform cooling
Solution Approach 2:
The thermal gradient enhancement structure implements local quality by creating spatially differentiated thermal conditions within the liquid helium. Different regions of the liquid helium serve different functional purposes: the first region maintains higher temperature for pressure stabilization, while the second region achieves lower temperature for superconducting operation, allowing simultaneous satisfaction of both pressure stability and low temperature requirements
2Temperature
If a thermal gradient enhancement structure is introduced to create temperature gradients, then temperatures below 4.2 degrees Kelvin can be achieved while maintaining positive pressure, but the device complexity increases
Solution Approach 1:
The thermal gradient enhancement structure utilizes the natural thermodynamic behavior of liquid helium and the inherent heat transfer properties of the system components to self-generate and maintain thermal gradients. The structure leverages heat conduction paths, convection patterns, and thermal radiation without requiring external active control systems, pumps, or additional energy input mechanisms, thereby achieving complex thermal management through passive self-organizing physical processes
Solution Approach 2:
The thermal gradient enhancement structure acts as an intermediary element that mediates between the heat source and the cold mass, creating controlled thermal resistance and heat flow paths. This intermediary structure enables the system to achieve desired temperature gradients through its geometric configuration and material properties rather than requiring complex active control mechanisms
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 extended magnetic field maintenance and higher operational currents by allowing temperatures below 4.2 degrees Kelvin while preventing air ingress and managing pressure, thus enhancing the operational safety and efficiency of cryogenic systems.
Implementation Method 1
a structure of a selected shape and material is added into the cryogenic vessel containing the cryogenic liquid to reduce mass transfer due to boiling and convection, and to reduce heat transfer due to diffusion
Implementation Method 2
reduce mass transfer due to boiling and convection
Implementation Method 3
reduce heat transfer due to diffusion
Implementation Method 4
a cryocooler to remove heat from the liquid helium
Implementation Method 5
the boiling liquid undergoes constant mixing, and thus heat is efficiently transferred across the vessel
Data Source
AI summary
Apparatus and methods to create and/or enhance thermal gradients in a body of cryogenic liquid contained in a vessel that is actively cooled by a cryocooler is provided. With such apparatus and/or methods temperature in one part of the body of liquid can be made lower than the temperature in another part of the body of liquid. Thus, the apparatus and/or methods enables cryogenic operation of a device at a temperature that is below that of the boiling point of the cryogenic liquid while simultaneously allowing the liquid to be at a pressure greater than atmospheric pressure to obviate the risk of air entering the cryogenic space. These apparatus and/or methods may find use in cryogenic systems used for magnetic resonance imaging, cyclotrons for radioisotope generation, cyclotrons for radiation therapy, high-energy particle accelerators, magnet systems for crystal growth and the like.