Fast-Switch Two-Field NMR With a Halbach Magnetic Tunnel
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Solution Overview
Problem
Existing two-field NMR spectrometers face limitations in achieving fast field-cycling over a wide range of magnetic fields, suffer from polarization loss during sample shuttling, and have restricted field strength and homogeneity, particularly at low fields.
Innovation Solution
A two-field NMR spectrometer design incorporating a low field permanent magnet system with a cylindrical ferromagnetic part, such as µ-metal, to shield external magnetic disturbances, and a magnetic tunnel with a Halbach dipole configuration, allowing for fast sample shuttling and high homogeneity across a wide magnetic field range from 100µT to 29.3T.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a magnetic tunnel is used to connect high field and low field magnet systems, then sample transfer time is reduced, but polarization loss during shuttling increases
Solution Approach 1:
A passive magnetic shield tube made of high-permeability material is introduced as an intermediary component between the high field and low field magnet systems. This shield tube creates a magnetic tunnel that guides magnetic field lines, maintaining field continuity during sample transfer and reducing polarization loss while enabling fast shuttling
2Adaptability or versatility
If low field magnet system is added for field-cycling, then field strength range is expanded, but susceptibility to external magnetic disturbances increases
Solution Approach 1:
A passive magnetic shield tube made of high-permeability material is positioned around the low field magnet system to act as a magnetic intermediary. This shield tube redirects external magnetic disturbance field lines around the sensitive low field region, protecting the system while allowing operation across an expanded field strength range from 100µT to 29.3T
3Productivity
If fast shuttling is implemented to reduce transfer time, then productivity increases, but polarization preservation decreases
Solution Approach 1:
The passive magnetic shield tube creates a magnetic tunnel that maintains field continuity during rapid sample transfer. This intermediary structure allows the sample to experience a continuous magnetic field environment during shuttling, enabling fast transfer speeds while preserving polarization through adiabatic field conditions
4Measurement precision
If magnetic shield tube is added to reduce external field interference, then measurement precision improves, but device complexity increases
Solution Approach 1:
A passive magnetic shield tube made of high-permeability material is integrated into the magnet system structure. This single intermediary component simultaneously shields against external magnetic disturbances and creates the magnetic tunnel for fast sample transfer, improving measurement precision without requiring multiple separate shielding systems
Solution Approach 2:
The passive magnetic shield tube serves multiple functions: it acts as a magnetic shield against external disturbances, creates the magnetic tunnel for fast sample transfer, and maintains field homogeneity in the low field region. This multi-functionality improves measurement precision while minimizing the increase in device complexity
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
Enables high-resolution spectroscopy with preserved polarization and enhanced sensitivity by minimizing external field interference and optimizing field homogeneity, facilitating rapid sample transfer between high and low fields.
Implementation Method 1
the low field permanent magnet system comprises a cylindrical ferromagnetic part, in particular comprising µ-metal, for shielding non-homogeneous external magnetic disturbance fields
Implementation Method 2
a magnetic tunnel with a Halbach dipole configuration
Implementation Method 3
a high field superconducting NMR magnet system for generating a homogenous magnetic field
Implementation Method 4
Nuclear magnetic resonance (='NMR') spectroscopy is a powerful tool in instrumental chemical analysis
Data Source
Figure 1
Figure 2A~2H
Figure 3
AI summary
A Two-Field-NMR spectrometer (10) for performing field-cycling NMR relaxometry experiments comprising a high field superconducting NMR magnet system (11') for generating a homogenous magnetic field parallel to a z-axis in a central region of the spectrometer for polarization of an NMR sample (12) and for detection of NMR signals; a low field magnet system (11") generating a variable homogenous magnetic field; a magnetic tunnel (14) connecting the center of the high field magnet system with the low field magnet system; and a shuttle system (13) designed for shuttling the NMR sample between the high field and the low field magnet system is characterized in that the magnetic tunnel is provided with a further magnet system (14'); and that the high field magnet system, the magnetic tunnel and the low field magnet system are arranged coaxially about the z-axis along a bore (15) of the high field magnet system. This allows fast field-cycling over a wide range of magnetic fields with very homogeneous low fields, excellent resolution of detected spectra at high fields, high detection sensitivity and preserving as much as possible the lifetime of manipulated spins.