NMR Probe Head Shielding Tube Assembly with Tensionable RF Seal
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Solution Overview
Problem
The existing NMR probe heads face challenges in assembling and disassembling the shielding tube without damaging the HF seal, requiring high forces that can lead to seal destruction and poor electrical ground contact.
Innovation Solution
A tensionable HF seal is introduced between the shielding disk and tube, allowing the shielding tube to be pushed over the disk without force in the first assembly state and mechanically braced in the second state for a conductive connection, ensuring a good HF seal and electrical ground connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the shielding tube is slipped over the RF seal, then the shielding tube can be installed, but the RF seal is destroyed due to high friction and shearing forces
Solution Approach 1:
The RF seal is divided into two functional parts: a flexible sealing element and a rigid support structure. The flexible element can be compressed during installation while the rigid support maintains structural integrity, allowing the shielding tube to be installed without destroying the seal.
Solution Approach 2:
A cushioning element is integrated into the RF seal structure to absorb the high friction and shearing forces that occur during installation. This cushioning prevents direct transmission of damaging forces to the seal, allowing force-free installation while maintaining seal integrity.
2Force
If a relatively large force is applied to install or remove the shielding tube, then the shielding tube can be securely positioned, but the seal and RF setup are damaged
Solution Approach 1:
The cushioning element within the RF seal structure absorbs and dissipates the installation forces, preventing them from damaging the seal and RF setup. This allows secure positioning of the shielding tube without compromising component durability.
Solution Approach 2:
The RF seal structure incorporates elements that change their mechanical properties during installation. The flexible sealing element can be compressed to reduce friction, and the overall structure can deform elastically to accommodate the shielding tube, reducing the force required for installation while maintaining reliability.
3Adaptability or versatility
If the RF seal is positioned high on the NMR probe head, then the shielding tube must be moved over the seal, but this leads to seal damage and requires large forces
Solution Approach 1:
The RF seal is segmented into a flexible element and rigid support, allowing it to be positioned high on the probe head while the flexible element accommodates the shielding tube movement without damage. The rigid support maintains the seal's position and integrity throughout the assembly process.
4Reliability
If the shielding tube is installed without force, then component damage is avoided, but electrical ground contact is insufficient
Solution Approach 1:
The RF seal is divided into sealing and grounding functions. The flexible sealing element provides RF sealing without force, while the rigid support structure with conductive elements ensures adequate electrical ground contact. This segmentation allows both force-free installation and good electrical contact to coexist.
Solution Approach 2:
The RF seal uses composite construction combining flexible conductive materials with rigid conductive supports. This composite structure provides both the flexibility needed for force-free installation and the conductivity required for good electrical ground contact, eliminating the trade-off between installation ease and electrical contact quality.
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 allows for damage-free assembly and disassembly of the NMR probe head, maintaining a strong HF seal and excellent electrical contact, reducing the risk of component damage and improving operational reliability.
Implementation Method 1
a tensionable RF seal is provided between the shielding disk and the shielding tube, which can be mechanically tensioned in such a way that an electrically conductive connection to the shielding tube is ensured around the circumference of the shielding disk
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
An NMR probe head (1) with one or more RF coils (2) arranged around a vertical axis of symmetry (z) and an RF network (3) surrounded by a shielding device (4) against external RF radiation, which includes an electrically conductive shielding tube (5) arranged along the z-axis and which can be slid around the RF coils and the RF network in the z-direction onto a base disk (6), is characterized in that a shielding disk (7) is provided at an axial distance from the base disk, that a clampable RF seal (8) is arranged between the shielding disk and the shielding tube in the assembled state, which is geometrically designed such that in a first assembly state the shielding tube can be slid over the shielding disk without tension and without force, and that in a second assembly state the RF seal can be mechanically clamped between the shielding disk and the shielding tube in such a way thatthat an electrically conductive connection to the shielding tube is ensured across the circumference of the shielding disc. This allows the shielding tube to be installed and removed without force, while still maintaining sufficient friction between the components after tightening the clamping ring to ensure adequate electrical conductivity between them.