Low vibration cryocooled cryostat
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional cryostats using cryocoolers experience significant vibrations due to gas pulses, which are detrimental for vibration-sensitive applications requiring displacements of nanometers or less, while traditional liquid helium cryostats are costly and require skilled operation.
Innovation Solution
A low vibration cryostat design featuring a cryocooler with a cold head, a housing, and a force balancing assembly using bellows and viscous dampers to mitigate vibrational forces, along with a support frame and damping assembly to minimize mechanical and acoustic coupling while maintaining thermal coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a GM-type pulse tube cryocooler is used to provide continuous cooling, then automatic operation and ease of use are improved, but mechanical vibrations increase due to periodic gas pulses
Solution Approach 1:
A flexible bellows is introduced as an intermediary element between the cryocooler cold head and the sample stage. This bellows acts as a mechanical decoupling element that transmits thermal energy while blocking the transmission of mechanical vibrations and gas pulses from the cryocooler to the sample environment, thereby resolving the contradiction between automatic cooling operation and vibration-free conditions.
Solution Approach 2:
The harmful mechanical vibrations and gas pulses are extracted and isolated from the sample environment by containing them within the bellows structure. The bellows absorbs and contains the periodic gas expansions and contractions, preventing these disturbances from reaching the sample stage while maintaining the cooling function.
2Stability of the object's composition
If rigid mounting is used to secure the cryocooler, then structural stability is improved, but vibration transmission to the sample increases
Solution Approach 1:
A flexible bellows structure is used to mount the cryocooler cold head. This flexible structure provides the necessary mechanical compliance to isolate vibrations while maintaining structural integrity and thermal coupling. The bellows expands and contracts with the gas pulses without transmitting these motions to the sample stage, thereby maintaining structural stability while preventing vibration transmission.
3Power
If liquid helium is used for cooling, then cooling power and simplicity are improved, but operational complexity and cost increase due to skilled technician requirements
Solution Approach 1:
The GM-type pulse tube cryocooler is a self-contained, autonomous cooling system that requires no external liquid helium supply infrastructure or skilled technician intervention for operation. The cryocooler automatically maintains the sample at cryogenic temperatures through its closed-cycle mechanical refrigeration system, eliminating the need for periodic liquid helium refilling, spill management, and specialized operational procedures associated with liquid helium systems.
4Object-affected harmful factors
If flexible hoses are used to connect the remote valve, then vibration isolation is improved, but structural rigidity decreases
Solution Approach 1:
The bellows structure serves as both a flexible connection element and a structural component. While flexible enough to isolate vibrations and accommodate gas pulse motions, the bellows is constructed with sufficient structural rigidity to maintain the mechanical integrity of the cryostat assembly and support the cold head mounting structure.
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 design achieves vibrational displacements of nanometers or less, enabling use in sensitive applications and reducing operational complexity and costs by eliminating the need for skilled technicians and complex helium supply chains.
Implementation Method 1
A first bellows extends between the housing and the flange of the cold head to mitigate the transfer of vibrational forces between the housing and the flange of the cold head
Implementation Method 2
A force balancing assembly is spaced from the first chamber and is arranged to apply an opposition force to the cold head which acts to oppose the first force applied to the cold head by the first bellows
Implementation Method 3
A low vibration cryostat design featuring a cryocooler with a cold head, a housing, and a force balancing assembly using bellows and viscous dampers to mitigate vibrational forces
Implementation Method 4
minimize mechanical and acoustic coupling while maintaining thermal coupling
Data Source
AI summary
A low vibration cryostat includes a cryocooler with a cold head having a flange and a cooling body extending from the flange. A housing is coupled to the cold head, with the housing having an opening receiving at least a portion of the cooling body. A first bellows extends between the housing and the flange to mitigate the transfer of vibrational forces between the housing and the flange. The first bellows, the flange, and the housing collectively define a first chamber. A force balancing assembly containing a second bellows is coupled to the housing and includes a second chamber spaced from the first chamber. The two chambers are arranged to create a net zero force on the cold head when the pressure in the bellows changes. A viscous damping assembly mitigates bouncing of the cold head on support springs.