NMR Probe Refrigerant Gas Cooling and Rotation
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Solution Overview
Problem
Existing NMR probes lack effective cooling mechanisms for dynamic nuclear polarization, leading to reduced radical relaxation times and decreased NMR signal strength, especially for solid samples, as they fail to maintain low temperatures and rotate the sample rotor efficiently.
Innovation Solution
An NMR probe design featuring a sample container rotated and cooled by a refrigerant gas, with a refrigerant gas space enclosed by an inner structure and a vacuum insulation space to minimize temperature rise, allowing for extended radical relaxation times and enhanced NMR signal strength by using helium gas to lower the sample temperature to liquid nitrogen levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the sample is cooled to extend radical relaxation time, then the NMR signal strength increases, but the device complexity increases due to the need for cooling mechanisms
Solution Approach 1:
The patent combines the cooling function and sample rotation function into a single refrigerant gas flow system. The refrigerant gas serves dual purposes: it cools the sample container to extend radical relaxation time and simultaneously drives the rotation of the sample rotor through gas pressure, thereby reducing device complexity while achieving the desired temperature control
Solution Approach 2:
The patent uses a vacuum insulation space surrounding the refrigerant gas space to create a thermally isolated inert environment. This vacuum barrier prevents heat transfer from the external environment to the cooled sample region, maintaining the low temperature required for extended radical relaxation time without requiring active heating compensation mechanisms
2Temperature
If liquid helium is used to cool the sample, then the radical relaxation time increases, but the loss of substance increases due to helium vaporization
Solution Approach 1:
The patent implements a closed-loop refrigerant gas circulation system where helium gas that vaporizes from liquid helium is captured, recondensed, and returned to the liquid helium reservoir. This recovery mechanism prevents helium loss to the environment while maintaining the low temperature required for extending radical relaxation time in the sample
3Measurement precision
If the sample rotor is rotated at high speed, then the measurement precision improves, but the device complexity increases due to the rotation mechanism
Solution Approach 1:
The patent uses pneumatic pressure from the refrigerant gas flow to drive the rotation of the sample rotor. The gas pressure differential created by the flow through the rotor structure provides the rotational force, eliminating the need for complex mechanical motors, bearings, or drive mechanisms while achieving the high rotation speeds necessary for precise NMR signal detection
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 effectively cools the sample and detection circuit, extending radical relaxation times and significantly increasing NMR signal strength, improving detection sensitivity in dynamic nuclear polarization methods.
Implementation Method 1
a rotation mechanism that blows a refrigerant gas to rotate the sample container and also cool the sample container
Implementation Method 2
an outer structure that defines a vacuum insulation space surrounding the refrigerant gas space
Implementation Method 3
a rotation mechanism that blows a refrigerant gas to rotate the sample container
Data Source
AI summary
A sample rotor is placed in a sample chamber inside an inner container. An air bearing type rotation mechanism blows a refrigerant gas (composed of a bearing gas and a driving gas) onto the sample rotor, to rotate the sample rotor and simultaneously cool the same. The refrigerant gas discharged from the air bearing type rotation mechanism is filled in an internal space (such as the sample chamber and a detection circuit chamber) of the inner container. An upper airtight chamber is formed between an outer container and the inner container. A lower airtight chamber is formed below a sealing bulkhead within a bottom unit. The upper and lower airtight chambers are in vacuum states to thereby function as vacuum insulation spaces for the internal space of the inner container.