Multiple Resonance NMR Coil for Uniform B1 Field
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Solution Overview
Problem
Conventional multiple resonant coil designs for NMR experiments suffer from arcing issues and limited sample size due to the separation of high and low frequency coils, leading to non-uniform B1 field distribution and restricted usable area.
Innovation Solution
The solenoid coil and high frequency resonator are electrically connected using capacitors, allowing the solenoid coil to extend fully and creating a birdcage resonator at high frequencies, while maintaining low frequency performance by connecting sections in parallel and using traps to isolate frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate high frequency resonator and low frequency solenoid coil are used, then frequency isolation is improved, but B1 field uniformity deteriorates and arcing occurs
Solution Approach 1:
The patent combines the high frequency resonator and low frequency solenoid coil into a single integrated coil structure. The coil is designed with a continuous winding that functions as both the high frequency resonator (when coupled with capacitors) and the low frequency solenoid coil, eliminating the need for separate coils and their associated isolation mechanisms.
Solution Approach 2:
The integrated coil structure serves multiple functions simultaneously: it acts as both the high frequency resonator for detecting NMR signals and the low frequency solenoid coil for generating the B1 field. This multi-functional design allows a single coil to replace what were previously two separate components, improving both field uniformity and eliminating arcing issues.
2Reliability
If solenoid coil length is reduced to prevent arcing, then arcing is reduced, but usable sample size deteriorates
Solution Approach 1:
By merging the high frequency resonator and low frequency solenoid coil into a single continuous structure, the patent eliminates the gap between separate coils that caused arcing. This allows the solenoid coil to extend to its full potential length without the risk of arcing, thereby maximizing the usable sample size while maintaining reliability.
3Adaptability or versatility
If separate coil systems are used for high and low frequencies, then frequency separation is improved, but device complexity deteriorates
Solution Approach 1:
The patent merges two separate coil systems (high frequency resonator and low frequency solenoid coil) into a single integrated coil structure. This simplification reduces the number of components, connections, and isolation mechanisms needed, thereby reducing device complexity while maintaining the ability to operate at both frequencies.
Solution Approach 2:
The single integrated coil performs the functions of both the high frequency resonator and the low frequency solenoid coil, making the system more universal and less complex. The coil can be tuned to different frequencies by adjusting the coupling capacitors, allowing it to serve multiple purposes with a 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
This design enhances the uniformity of the B1 field distribution, increasing the usable sample size by approximately two and a half times compared to conventional systems, reducing arcing and enabling more efficient NMR experiments.
Implementation Method 1
A radio-frequency (RF) field or B1 field is then applied to the sample to rotate the net magnetization in a pulse sequence. Sample coils that surround the sample not only create the B1 field for the pulse sequence
Implementation Method 2
a high frequency resonator with a reduced E-field (the E-field causes heating) and one highly efficient solenoid coil for the lower frequencies
Implementation Method 3
The solenoid coil and high frequency resonator are electrically connected using capacitors, allowing the solenoid coil to extend fully and creating a birdcage resonator at high frequencies
Implementation Method 4
using traps to isolate frequencies
Implementation Method 5
the interactions are time-dependent and can be averaged by physically spinning the sample (at high rotation speeds up to 80 kHz) at an inclination of the so-called magic angle (54.74°) with respect to the direction of the external B0 magnetic field. The averaging causes the normally broad lines become narrower, increasing the resolution
Data Source
AI summary
A multiple resonance sample coil for a magic angle spinning nuclear magnetic resonance probe is comprised of a solenoid coil that resonates at low frequencies and a resonator that resonates at high frequencies. The ends of the low frequency solenoid coil are electrically connected to the high frequency resonator to eliminate arcing and allow the solenoid coil to extend the full width of the resonator. In some embodiments, the high frequency resonator is constructed from the outermost turns of the solenoid coil in the form of a birdcage resonator. In another embodiment, the solenoid coil is electrically connected to one turn of the resonator and the other turn is used as part of a trap to shunt the resonator at low frequencies.