NMR Magnet Temperature Control via Isothermal Chamber and Thermal Bridge
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Solution Overview
Problem
Current NMR magnet systems face challenges in precise temperature control, leading to magnetic field instability and prolonged measurement times due to temperature fluctuations, especially when dealing with varying test sample temperatures, and existing solutions fail to achieve accurate temperature control in the millikelvin range.
Innovation Solution
A temperature-control system for NMR magnet systems that surrounds the permanent magnet with an internally and externally closed isothermal chamber, using a heat-conducting body between the shim system and the magnet, and controlling the temperature of the inner wall and heat-conducting body to maintain a stable magnetic field, independent of external heat inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the magnet temperature is decreased to maximize the B0 field and slow down thermal relaxation, then the magnetic field strength is improved, but the temperature control precision deteriorates due to difficulty in maintaining stable temperature in the millikelvin range
Solution Approach 1:
The temperature control system is divided into separate functional components: a first temperature control unit for controlling the magnet temperature and a second temperature control unit for controlling the sample temperature. This segmentation allows independent optimization of each temperature control loop, enabling millikelvin precision for the magnet while maintaining flexibility for sample temperature variation.
Solution Approach 2:
A thermally conductive intermediary structure is introduced between the magnet and the sample region. This intermediary serves as a thermal bridge that can be selectively coupled or decoupled, allowing heat to be conducted away from the magnet when needed while maintaining thermal isolation when stable temperature is required, thus enabling precise temperature control.
2Adaptability or versatility
If variable test sample temperature is introduced, then the measurement versatility is improved, but the magnetic field homogeneity deteriorates due to temperature gradients emerging in the magnet system
Solution Approach 1:
The system is segmented into thermally independent zones: the magnet region with its own temperature control and the sample region with separate temperature control. This allows the sample temperature to be varied for different measurement requirements without affecting the magnet temperature, thereby maintaining field homogeneity while achieving measurement versatility.
Solution Approach 2:
Different thermal conditions are applied to different parts of the system: the magnet region maintains a stable, controlled temperature for field homogeneity, while the sample region allows variable temperature for measurement versatility. This local differentiation of thermal properties resolves the contradiction between versatility and stability.
3Stability of the object's composition
If the magnet temperature is actively controlled to minimize fluctuations, then the magnetic field stability is improved, but the device complexity increases due to additional temperature control systems
Solution Approach 1:
The temperature control system is segmented into modular units with distinct functions: a first temperature control unit for the magnet and a second temperature control unit for the sample. Each unit operates independently with its own sensors and actuators, simplifying the overall control architecture while achieving the required field stability.
Solution Approach 2:
The system employs feedback control mechanisms where temperature sensors continuously monitor the magnet temperature and sample temperature, and the control units adjust heating/cooling elements accordingly. This closed-loop feedback ensures magnetic field stability through automatic temperature regulation without requiring overly complex manual control systems.
4Productivity
If temperature control is implemented to reduce measurement time, then the productivity is improved, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The control system is segmented into independent temperature control units that can operate simultaneously and autonomously. This modular approach allows rapid temperature adjustment and stabilization without requiring complex coordinated control, thereby reducing measurement time while keeping the control system manageable in complexity.
Solution Approach 2:
The temperature control system operates continuously to maintain optimal temperatures, preventing the need for repeated heating/cooling cycles during measurements. This continuous action ensures rapid thermal equilibrium is achieved and maintained, improving productivity without requiring complex intermittent control mechanisms.
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 enables precise temperature control of the magnet to within a few millikelvin, reducing magnetic field drift and measurement time, allowing for stable field homogeneity and efficient NMR measurements without additional sample temperature control.
Implementation Method 1
a first insulation chamber (5) surrounding the permanent magnet arrangement (1) so as to thermally shield it
Implementation Method 2
at least one heat-conducting body (7) arranged between the shim system (4) and the H0 coil on one hand and the permanent magnet arrangement (1) on the other hand
Implementation Method 3
one or more arrangements (6) controlling a temperature T1 of the first insulation chamber (5), wherein the shim system (4), the H0 coil and the NMR probehead (3) are arranged outside the first insulation chamber (5) in the central air gap (2)
Data Source
AI summary
A temperature-control system for an NMR magnet system. A permanent magnet arrangement (1) with a central air gap (2) generates a homogeneous static magnetic field inside the air gap. A probehead (3) transmits RF pulses and receives RF signals from a test sample (0). An H0 coil changes the amplitude of the static magnetic field. A shim system (4) in the air gap further homogenizes the magnetic field. A first insulation chamber (5) surrounds and thermally shields the permanent magnet arrangement and includes an arrangement (6) controlling a temperature T1 of the first insulation chamber. The shim system, the H0 coil and the NMR probehead are arranged outside the first insulation chamber in the air gap. A heat-conducting body (7) is arranged between the shim system and the H0 coil on one side and the permanent magnet arrangement on the other, thereby enhancing field stability and suppressing drift.