Cryogenic Low-Noise Amplifier With Low-Vacuum Thermal Isolation
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Solution Overview
Problem
Existing systems for receiving low-power radio frequency signals from distant space vehicles, such as interplanetary probes, face challenges in sensitivity and noise reduction due to technological and economic limitations, particularly in maintaining cryogenic temperatures for radiofrequency amplifiers, which increases complexity and maintenance costs.
Innovation Solution
A low-noise radio frequency amplifier is designed with a hermetic cryostat enclosure, using a cold head with multiple cryogenic stages and nanostructured thermal insulating materials to maintain low temperatures while reducing thermal losses and simplifying maintenance, allowing operation at cryogenic temperatures without the need for high vacuum conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amplifier is cooled to cryogenic temperatures to reduce thermal noise, then the signal-to-noise ratio is improved, but the system complexity and maintenance requirements increase
Solution Approach 1:
The patent changes the thermal parameter of the amplifier by cooling it to cryogenic temperatures (below 15K) to reduce thermal noise. This parameter change directly improves the signal-to-noise ratio while the patent manages the associated complexity through specific design choices regarding vacuum requirements
Solution Approach 2:
The patent uses a vacuum environment (inert atmosphere) within the cryostat to enable cryogenic operation. By requiring only low vacuum conditions rather than high vacuum, the patent simplifies the system while still providing the necessary inert environment for cryogenic cooling and reducing thermal conduction losses
2Loss of energy
If high vacuum conditions are maintained in the cryostat, then thermal losses are reduced, but the maintenance complexity and costs increase
Solution Approach 1:
The patent changes the vacuum parameter from requiring high vacuum conditions to requiring only low vacuum conditions (pressure between 10^-3 and 10^-6 bar). This parameter relaxation significantly reduces maintenance complexity and costs while still achieving adequate thermal insulation performance
Solution Approach 2:
The patent employs a simpler vacuum system that can be more easily maintained or replaced. The low vacuum requirement allows for simpler pumping systems and easier maintenance procedures, effectively treating the vacuum system as a more replaceable component rather than a permanent complex infrastructure
3Ease of repair
If the cold head is disassembled for maintenance, then repairs can be performed, but thermal insulation performance deteriorates and requires re-vacuuming
Solution Approach 1:
The patent maintains a low vacuum inert environment that is sufficient for thermal insulation but can be easily restored after maintenance. The relaxed vacuum requirement means that after cold head disassembly and reassembly, the vacuum system can be quickly re-established without complex procedures, minimizing the time the system operates with degraded thermal insulation
Solution Approach 2:
The patent design allows for preliminary preparation of the vacuum system such that it can be quickly re-established after maintenance. The vacuum pumping capability is built into the design to be activated after cold head reassembly, ensuring thermal insulation performance is restored promptly
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 solution enhances the sensitivity and signal-to-noise ratio of the amplifier, reducing thermal noise and maintenance costs, while improving operational availability and reducing downtime for maintenance operations.
Implementation Method 1
the interior space of the enclosure is cooled by means of a cold head which pumps the heat inside the enclosure
Implementation Method 2
the hermetic space delimited by the enclosure of the cryostat is filled with a nanostructured thermal insulating material based on silica in the form of an airgel
Implementation Method 3
an internal pressure reduced with respect to the external atmospheric pressure is maintained
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A radiofrequency amplifier comprises a low noise amplifier (25) held in a hermetic enclosure (11) of a cryostat cooled by a cold head (30) and in which a mild vacuum is maintained. The low noise amplifier receives the signals from an input coupler (23) and transmits the signals through an output coupler (26). The input coupler (23) and output coupler (26) are embodied in respect of a structural part with a material of thermal conductivity equal to or lower than 50W/m.K and in respect of an electrically conducting part by a plating on at least one of the faces of said structural part of a material of electrical conductivity greater than 10E7 Siemens/m. The cold head (30) comprises at least two stages (302, 303) whose cold terminations (304, 305) are at different cryogenic temperatures, a terminal stage (305) operating at a temperature close to the temperature at which the low noise amplifier (25) must operate and at least one intermediate stage operating at an intermediate temperature.