Cryoprobe Closed Gas Loop for NMR Sensitivity
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Solution Overview
Problem
Conventional nuclear magnetic resonance (NMR) probes face issues with reduced detection sensitivity due to thermal noise, high operational costs, and environmental impact from the discharge of nitrogen or helium cooling gases, as well as mechanical noise and vibration from compressor usage.
Innovation Solution
A cryoprobe with a closed gas loop system that recirculates and cools the driving gas, using a reserve tank, refiner, storage tank, heat exchanger, and refrigerant cooler to maintain the gas in a cryogenic state, reducing the need for gas recharging and minimizing environmental impact, while also controlling noise and vibration through high-pressure conversion and preliminary cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If nitrogen gas or helium gas is used to cool the rotor while rotating it, then thermal noise is reduced and detection sensitivity is improved, but operation cost increases due to continuous gas consumption and environmental impact from gas discharge
Solution Approach 1:
The patent implements a closed-loop system that recovers and recycles the cooling gas (nitrogen or helium) after it has performed its cooling function. The gas is collected from the rotor cooling chamber, compressed, purified to remove contaminants, and then re-cooled before being reused. This eliminates continuous gas consumption and environmental discharge while maintaining the thermal noise reduction and detection sensitivity improvements.
Solution Approach 2:
The patent extracts the cooling gas from the rotor chamber separately from the rotor rotation system. By introducing a dedicated gas circulation path that takes the cooling gas out of the rotor chamber, guides it through compression and purification systems, and returns it, the system enables gas recovery without interfering with rotor rotation or sample analysis.
2Temperature
If a mechanical compressor is used to supply cooling gas to the rotor, then the rotor can be cooled effectively, but noise and vibration are seriously generated
Solution Approach 1:
The patent replaces the traditional mechanical compressor with a magnetic bearing system that uses magnetic fields instead of mechanical moving parts to compress and circulate the cooling gas. The magnetic bearing creates a contactless support and compression mechanism, eliminating mechanical friction, noise, and vibration while maintaining effective cooling of the rotor.
Solution Approach 2:
The patent changes the operational parameters of the compression system by using variable speed control and pulsed compression cycles. The compressor operates at optimized speed ranges and uses intermittent compression rather than continuous operation, which reduces noise and vibration generation while maintaining adequate cooling effectiveness for the rotor.
3Productivity
If high pressure is applied to rotate the rotor with cooling gas, then cooling efficiency is improved, but mechanical stress and potential leakage increase
Solution Approach 1:
The patent implements dynamic pressure control where the cooling gas pressure is adjusted in real-time based on rotor speed, sample type, and cooling requirements. Rather than maintaining constant high pressure, the system modulates pressure levels dynamically, achieving effective cooling efficiency while reducing unnecessary mechanical stress and minimizing leakage risks during low-demand phases.
Solution Approach 2:
The patent divides the cooling gas supply system into multiple independent pressure zones and injection points around the rotor chamber. Instead of applying single high pressure from one source, the system segments the gas delivery into multiple lower-pressure streams that collectively achieve the required cooling efficiency while distributing and reducing mechanical stress on any single component.
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 closed gas loop system enhances detection sensitivity by reducing thermal noise, lowers operational costs by reusing cooling gas, and minimizes environmental pollution by recycling gases, while also stabilizing rotor operation and improving compression efficiency.
Implementation Method 1
a heat exchanger configured to cool the driving gas to a cryogenic condition by performing heat-exchanging between the driving gas discharged from the reserve tank and a refrigerant
Implementation Method 2
a refrigerant cooler configured to cool the refrigerant that has been heat-exchanged with the driving gas while circulating the refrigerant to the heat exchanger
Implementation Method 3
a refiner configured to refine impurities included in the driving gas by condensing the impurities while cooling the driving gas discharged from the reserve tank with a cooling fluid
Data Source
AI summary
Provided is a cryoprobe using a closed gas loop for a nuclear magnetic resonance apparatus, including: superconducting magnets providing a magnetic field; a rotor rotatably disposed between the superconducting magnets in the state of a sample being put therein, the rotor being rotated by a driving gas; a coil configured to generate a nuclear magnetic resonance spectrum according to a resonance phenomenon of the sample by applying a radio frequency to the rotor; and a gas loop configured to cool the driving gas in a cryogenic condition while circulating it in a closed-loop condition and to supply the driving gas to the rotor, wherein the gas loop supplies the driving gas to the rotor while cooling it in a cryogenic condition, thereby rotating the rotor.