Joule-Thomson Cooled IR Detector for Lower Energy Cryogenic Operation
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Solution Overview
Problem
Current cooled detection devices require significant energy consumption due to low thermal efficiency, typically achieving only 8-10% cooling efficiency with conventional designs, making them inefficient for effective stray electrical interference reduction and optimal performance.
Innovation Solution
A cooled detection device incorporating a Joule-Thomson cooler in a closed loop with a gas mixture and a cold table, which reduces energy consumption by using a gas mixture and additives like HFE-7100 to achieve a working temperature range of 120-200 K, and includes a compressor with a pressure gradient management system to enhance cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling devices are used to cool the detection circuit, then the detection device can operate at low temperature to reduce stray electrical interference, but the energy consumption is significant due to low thermal efficiency (8-10%)
Solution Approach 1:
The patent changes the thermodynamic parameters of the cooling system by using a gas mixture (e.g., nitrogen, hydrogen, helium) instead of conventional cooling methods. The gas mixture is compressed to high pressure (e.g., 200-500 bar) and then expanded through a Joule-Thomson valve, utilizing the Joule-Thomson effect to achieve cooling. This parameter change (from conventional cooling to compressed gas expansion) improves thermal efficiency while maintaining the required low operating temperature (e.g., 77-200 K) for the detection circuit, thereby reducing energy consumption.
Solution Approach 2:
The patent utilizes phase transitions of the gas mixture during the cooling process. The gas is compressed to a state where it can undergo phase transition during expansion through the Joule-Thomson valve, absorbing heat from the detection circuit. The phase change from high-pressure gas to lower-pressure gas (with potential liquid-vapor transition) provides efficient heat absorption, improving the cooling efficiency from the conventional 8-10% to a higher value, thus reducing the energy required to maintain low temperature operation.
2Measurement precision
If specific substrates (Mercury, Cadnium, Tellurium) are used to achieve significant detection performance, then the detection sensitivity is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the operating temperature parameter of the detection device to a specific range (e.g., 77-200 K, preferably 90-150 K) using the compressed gas cooling system. This temperature parameter optimization allows the use of simplified substrate materials while maintaining high detection sensitivity. The controlled temperature environment compensates for the reduced complexity of the substrate, achieving a balance between detection performance and device simplicity.
Solution Approach 2:
The patent introduces a cold shield as an intermediary element between the external environment and the detection circuit. The cold shield, cooled to the operating temperature (e.g., 77-200 K), blocks thermal radiation and stray electrical interference from reaching the photodetector. This intermediary structure allows the use of simpler substrate materials while maintaining detection sensitivity, as the cold shield provides the necessary thermal and electrical isolation without requiring complex substrate compositions.
3Measurement precision
If the detection device is cooled to low temperature to limit stray electrical interference, then the signal-to-noise ratio is improved, but the thermal inertia and vibration increase
Solution Approach 1:
The patent segments the cooling system into distinct functional zones: a cold table that directly contacts the detection circuit, a cold shield that surrounds the detection area, and a gas circulation system. This segmentation allows only the necessary components (detection circuit and immediate surroundings) to be cooled to low temperature, while other parts remain at ambient temperature. This reduces the overall thermal inertia of the device while maintaining the low temperature required for high signal-to-noise ratio in the detection circuit.
Solution Approach 2:
The patent applies local quality by cooling only the specific regions that require low temperature operation (detection circuit and cold shield) while keeping other parts of the device at higher temperatures. The cold table provides localized cooling at the detection site, and the gas mixture is directed specifically to these areas. This localized approach minimizes the total mass at low temperature, reducing thermal inertia and vibration, while still achieving the necessary signal-to-noise ratio improvement in the detection circuit.
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 solution significantly reduces energy consumption and improves cooling efficiency, allowing the detection device to operate effectively within the desired temperature range while minimizing vibration and thermal inertia, thus enhancing detection performance.
Implementation Method 1
a Joule-Thomson cooler fitted with a cold table thermally and mechanically connected to the detection circuit and the readout circuit, the cold table containing an internal cavity, a relief port arranged at an input of the internal cavity, a compressor having an output supplying the relief port with gas and an input receiving said relaxed gas from an output of the internal cavity
Data Source
AI summary
A detection device for infrared radiation has a detection circuit of infrared radiation equipped with at least one photodetector. A readout circuit is electrically connected to the detection circuit, and is configured to process the signal emitted by the detection circuit. A Joule-Thomson cooler cools a cold table thermally and mechanically connected to the detection circuit and the readout circuit. The cold table including an internal cavity supplied with gaseous mixture. A relief port of the gas mixture is arranged at an input in the internal cavity. An output of the compressor feeds the relief port in a gaseous mixture. The input of the compressor receives the relaxed gaseous mixture from an output of the internal cavity.