Gas gap heat switch configuration
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Solution Overview
Problem
Existing cryogenic cooling systems using sorption pumps are limited in their operational modes, as they cannot raise the temperature of individual stages above the threshold temperature without causing the heat switch to transition into a closed state, limiting the achievable temperatures and system performance.
Innovation Solution
A cryogenic cooling system with a thermal link between the cooled plate and the sorption pump, allowing independent control of the sorption pump temperature and maintaining it below the nominal transition temperature, enabling the heat switch assembly to remain open during heating of the target assembly without affecting the cooled plate's temperature, and incorporating a sorption heater to control the sorption pump's temperature for transitioning between open and closed states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the target assembly temperature is raised above the sorption pump threshold temperature, then the target assembly can achieve higher temperatures, but the sorption pump will desorb gas molecules causing the heat switch to transition to closed state
Solution Approach 1:
The system is divided into thermally isolated segments: the target assembly can be heated independently while the sorption pump is thermally anchored to the cryogenic refrigerator through a thermal link, preventing heat propagation to the pump and maintaining its low temperature state
Solution Approach 2:
A thermal link acts as an intermediary between the cryogenic refrigerator and the sorption pump, providing a dedicated thermal pathway that isolates the pump from heat generated at the target assembly, allowing independent temperature control of each component
2Temperature
If the heat switch is kept open during target assembly heating, then the cooled plate temperature remains stable, but the target assembly cannot be heated above the sorption pump threshold temperature
Solution Approach 1:
The thermal link serves as a thermal intermediary that decouples the temperature control of the target assembly from the sorption pump, enabling the target to be heated to higher temperatures while the pump remains thermally anchored to the cryogenic refrigerator
Solution Approach 2:
The system enables dynamic temperature control where the target assembly can be heated independently above the pump threshold temperature while the heat switch remains open, providing flexible operational modes for different experimental requirements
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 configuration allows for greater control over the system's temperature, enabling new operational modes, such as raising the target assembly's temperature above the cooled plate's temperature without closing the heat switch, and maintaining high temperature operation of the target assembly without affecting the cooled plate, thus enhancing system flexibility and performance.
Implementation Method 1
When the temperature of the pump decreases below a threshold transition temperature the sorption pump adsorbs gas molecules from the switch, thus opening the switch
Implementation Method 2
when the temperature of the pump rises above this transition temperature the pump desorbs these gas molecules so as to reintroduce them into the chamber and close the switch
Implementation Method 3
When the switch is closed, the gas inside the chamber facilitates heat transfer between the conductors by conduction
Data Source
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AI summary
A cryogenic cooling system is provided comprising: a cooled plate (2) thermally coupled to a cryogenic refrigerator (9), a heat switch assembly and a target assembly (5). The target assembly (5) comprises a target refrigerator (12) configured to obtain a lower base temperature than the cryogenic refrigerator (9). The heat switch assembly (18) comprises one or more gas gap heat switches, the heat switch assembly (18) having a first end thermally coupled to the cooled plate (2) and a second end thermally coupled to the target assembly (5). A sorption pump (22) is provided for controlling the thermal conductivity across the heat switch assembly (18) in accordance with the temperature of the sorption pump (22) The sorption pump (22) is thermally coupled to the cryogenic refrigerator (9), by a thermal link (46) extending from the cooled plate (2) to the heat switch assembly (18). The sorption pump (22) is arranged at a position along the thermal link (46) between the heat switch assembly 18 and the cooled plate (2).