Cryostat Cavity Evacuation to Cut Thermal Load After Cooling Failure
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Solution Overview
Problem
Cryostats with active cooling systems face challenges in maintaining the superconducting state of magnet coils during cooling failures, leading to potential destruction and high costs associated with liquid helium consumption and structural height/weight issues.
Innovation Solution
A cryostat design featuring a pump device that evacuates a cavity surrounding the cooling arm upon cooling failure, reducing thermal coupling through the use of a first cryogenic fluid for efficient heat transfer, which is then removed, creating a vacuum that significantly reduces heat transport mechanisms and minimizes thermal load on the object being cooled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the thermal mass in the cryostat is increased to extend the time between cooling failures and service intervention, then the duration of action is improved, but the structural height and weight increase
Solution Approach 1:
The patent changes the thermal state of the cavity by evacuating it to create vacuum insulation, fundamentally altering the heat transfer parameters. This allows the system to extend operational duration without increasing thermal mass, as the vacuum barrier dramatically reduces heat influx to the object being cooled
Solution Approach 2:
The patent creates an inert vacuum environment in the cavity to eliminate heat transfer through conduction and convection. This inert atmosphere (vacuum) provides thermal insulation without adding physical mass, resolving the contradiction between extending operational duration and minimizing structural weight
2Quantity of substance
If liquid helium is replenished to replace evaporated helium, then the quantity of substance is improved, but the cost increases substantially
Solution Approach 1:
The patent converts the harmful thermal radiation and heat transfer that occur during cooling failure into a beneficial vacuum insulation state. By evacuating the cavity when cooling fails, the system prevents further helium evaporation caused by thermal influx, thus protecting the remaining helium quantity without requiring replenishment
Solution Approach 2:
The patent utilizes the phase transition concept by creating a vacuum (removing gas phase helium vapor) in the cavity to prevent heat transfer. This phase change from gaseous helium to vacuum state provides thermal insulation that preserves the liquid helium in the cryocontainer
3Reliability
If the cooling arm remains thermally coupled to the object being cooled during cooling failure, then the cooling function is maintained, but the thermal load increases significantly
Solution Approach 1:
The patent dynamically changes the thermal coupling state of the cavity based on operational conditions. During normal operation, the cavity is filled with helium for thermal coupling; during cooling failure, the cavity is evacuated to reduce thermal load. This dynamic adaptation allows the system to maintain reliability while minimizing energy loss
Solution Approach 2:
The cavity acts as an intermediary between the cooling arm and the object being cooled. By evacuating this intermediary space, the patent eliminates the thermal bridge that would otherwise conduct heat from the cooling arm to the object, thereby reducing thermal load while maintaining the superconducting state
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 effectively reduces the thermal load on the object being cooled by up to 99% upon cooling failure, minimizing structural height and weight while preventing helium loss and maintaining the superconducting state, thus extending the time before service intervention is required.
Implementation Method 1
the cavity is configured to be evacuated upon failure of the cooling function of the cold head
Implementation Method 2
The thermal coupling of the cooling arm to the object to be cooled occurs through the cavity using the first cryogenic fluid
Implementation Method 3
The heat transfer is supported primarily by convection and thermal conduction in the cryogenic fluid
Implementation Method 4
the thermal load can be decreased in a simple manner by a cooling arm in the event of a loss of the active cooling
Data Source
AI summary
A cryostat arrangement (1), with a vacuum container (2) and an object (4) to be cooled, is provided, wherein the object (4) to be cooled is arranged inside the vacuum container (2) comprising a neck tube (8) leading to the object (4) to be cooled. A closed cavity (9) is formed around the cooling arm (10) of a cold head (11), wherein the cavity (9) in normal operation is filled at least partly with a first cryogenic fluid (34), and wherein a first thermal coupling component (15) is provided for the thermal coupling of the first cryogenic fluid (34) in the cavity (9) to the object (4) to be cooled. The cryostat arrangement (1) further comprises a pump device (14), to which the cavity (9) is connected, and with which the cavity (9) is configured to be evacuated upon failure of the cooling function of the cold head (11). Various cryostat configurations are provided.