RS Coil Shielding for EPR Thermal Decoupling
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Solution Overview
Problem
Existing EPR apparatuses equipped with Rapid Scan (RS) coils face limitations such as inadequate thermal and magnetic decoupling from the main magnet, heat management issues, acoustic noise, high operating voltage management, and poor field homogeneity over the sample volume, leading to suboptimal performance and user discomfort.
Innovation Solution
The design of an RS coil assembly with thermally and magnetically decoupled coil devices, featuring a coil support with integrated cooling chambers, non-magnetic electrically conducting shielding plates, and a multichamber actively cooled topology to minimize impedance and maximize field homogeneity, along with specific winding patterns and materials for efficient heat management and reduced acoustic noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If RS coils are placed close to the main magnet to improve field homogeneity, then field homogeneity improves, but thermal coupling and magnetic interference from Eddy currents worsen
Solution Approach 1:
A non-magnetic, electrically conductive shielding plate is introduced as an intermediary component between the RS coil and the main magnet pole piece. This shielding plate prevents direct thermal and magnetic coupling while allowing the coil to operate close to the magnet for field homogeneity. The shielding plate is actively cooled through integrated cooling channels to dissipate heat generated by Eddy currents.
Solution Approach 2:
The coil assembly is segmented into distinct functional components: the RS coil winding, the non-magnetic shielding plate, and the cooling system. This segmentation allows each component to perform its specific function independently - the coil generates the magnetic field, the shielding plate blocks thermal and magnetic interference, and the cooling system manages heat dissipation.
2Measurement precision
If high microwave power is used to increase signal amplitude, then sensitivity improves, but heat generation in the resonator worsens
Solution Approach 1:
A liquid cooling system with cooling channels is integrated into the resonator structure to actively remove heat generated during high-power microwave operation. The cooling fluid circulates through these channels to dissipate thermal energy, enabling sustained high-power operation without excessive temperature rise that would degrade measurement precision.
3Volume of moving object
If the coil device is made compact to fit in the magnet air gap, then space utilization improves, but heat dissipation capability worsens
Solution Approach 1:
The cooling system utilizes the vertical dimension by integrating cooling channels within the shielding plate structure, allowing heat dissipation pathways to extend in the z-direction rather than requiring increased lateral footprint. This enables effective heat management within the constrained horizontal space of the magnet air gap.
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 configuration ensures stable and homogeneous magnetic fields, effective heat dissipation, reduced acoustic noise, and optimized mechanical integration, enhancing the sensitivity and accuracy of RS EPR measurements while maintaining compactness and efficiency.
Implementation Method 1
The coil support comprises integrated cooling chambers which are connected to cooling liquid supply channels
Implementation Method 2
cooling liquid supply channels
Implementation Method 3
a coil field shielding means comprising an electrically conducting, non-magnetic, shielding plate which is mounted laterally onto the coil support means, between the coil winding(s) and the corresponding pole piece of the main field magnet
Implementation Method 4
RS coils must be able to deliver a magnetic field with the following performances: Maximum amplitude in the range of 200G peak-to-peak
Implementation Method 5
the field of the main magnet (producing the B0 field) must be stable in time and highly homogeneous spatially in the vicinity of the sample
Data Source
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AI summary
This invention concerns an Electron Paramagnetic Resonance apparatus (9), such as an EPR spectrometer or an EPR imager, mainly comprising a main field magnet (10) with two opposed pole pieces (11) defining an airgap between them, an RS coil assembly (1') comprising two opposed RS coil devices (1) having each at least one coil winding, a microwave resonator (12) coupled with a microwave guide (14), a sample holder, holding the sample (13) to be analyzed, as well as a current source (1") adapted to be used as a coil driver. EPR apparatus (9) characterized in that each of the two opposed RS coil devices (1) comprises: i) a coil support means having a plate like body and comprising recesses designed to accommodate the at least one coil winding and at least one cooling chamber volume which is connected to cooling liquid supply channels (7), and ii) an RF shielding means comprising an electrically conducting, non-magnetic, shielding plate which is mounted laterally onto the coil support means, between the coil winding(s) and the corresponding pole piece (11) of the main field magnet (10), and contacts said cooling chamber volume.