Unbrazed Joint for RF Resonators
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Solution Overview
Problem
The manufacture of resonant high power microwave devices, such as waveguides for particle accelerators, is costly and prone to manufacturing errors due to the need for precise internal geometries and simultaneous RF and vacuum joints, with existing methods like brazing being expensive and unreliable, and alternative approaches either separating RF and vacuum joints or being bulky and costly.
Innovation Solution
An unbrazed joint structure using copper-plated stainless steel flanges with knife edges and a thicker copper gasket that functions as an integral part of the resonator, providing a precise internal geometry, reliable vacuum seal, and high-quality RF shielding, allowing for easy disassembly and reassembly without degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brazing is used to join copper resonator cavities, then good vacuum joint and RF contact are achieved, but manufacturing cost increases and manufacturing precision decreases due to thermal stress and difficulty in correction
Solution Approach 1:
The invention changes the joining method from brazing (thermal process) to mechanical compression with elastomeric gaskets (mechanical process). This parameter change eliminates thermal stress that distorts copper cavity dimensions during brazing, thereby maintaining internal geometry precision while still achieving reliable vacuum seals through the compliant gasket material.
Solution Approach 2:
The invention introduces elastomeric gaskets as intermediary elements between copper flanges. These gaskets serve as mediators that simultaneously provide vacuum sealing and accommodate dimensional tolerances without requiring precise machining, thus resolving the contradiction between seal quality and manufacturing precision.
2Reliability
If brazing is used to join copper resonator cavities, then good vacuum joint and RF contact are achieved, but manufacturing cost increases and error correction becomes impossible
Solution Approach 1:
The invention changes the joining process from irreversible brazing to reversible mechanical assembly using compression gaskets. This allows for error correction and reassembly, significantly reducing manufacturing costs while maintaining joint reliability through the compliant gasket material that compensates for tolerances.
Solution Approach 2:
The elastomeric gaskets serve as disposable or replaceable components that are inexpensive compared to brazing operations. If errors occur during assembly, the gaskets can be replaced without requiring expensive brazing equipment or skilled brazing operations, thereby reducing manufacturing costs.
3Reliability
If conflat vacuum seal technology is used with stainless steel flanges, then reliable vacuum seal is achieved, but internal geometry precision is insufficient for resonators
Solution Approach 1:
The invention uses composite material construction where stainless steel flanges are copper-plated on the interior surfaces. The stainless steel provides mechanical strength and rigidity for reliable vacuum sealing, while the copper plating provides the necessary electrical conductivity and RF performance. This composite approach allows the flanges to serve dual functions: structural support and RF conductor.
Solution Approach 2:
The invention applies different material properties to different parts of the flange: the exterior and structural portions use stainless steel for mechanical strength and vacuum sealing, while the interior surfaces contactting RF fields are copper-plated for electrical conductivity. This local quality differentiation resolves the contradiction between vacuum seal reliability and RF performance precision.
4Reliability
If copper gaskets are crushed between copper flanges, then simultaneous RF and vacuum joint is achieved, but internal dimensions are distorted and disassembly is risky
Solution Approach 1:
The invention uses elastomeric gaskets as intermediaries between flanges, replacing the traditional copper gasket approach. These elastomeric materials are compliant and can be compressed to provide sealing without exerting excessive localized pressure that would distort the internal dimensions of precision copper cavities. The gaskets act as stress-distributing intermediaries.
Solution Approach 2:
The invention changes the gasket material parameter from soft copper to elastomeric material. This parameter change allows the gasket to be compressed between flanges to provide vacuum sealing and RF contact without the risk of distorting cavity dimensions, as elastomers are more compliant and distribute pressure more evenly than copper gaskets.
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 reduces production costs by more than an order of magnitude, maintains precise resonator dimensions, and achieves quality factors comparable to brazed copper structures, while allowing for cooling and magnetic focusing integration, making it suitable for high power microwave components.
Implementation Method 1
the first and second knife edges are pressed into opposing proximal and distal faces of the central component respectively, thereby simultaneously forming vacuum and RF seals
Implementation Method 2
An unbrazed joint structure using copper-plated stainless steel flanges
Data Source
AI summary
A resonant apparatus such as a resonant waveguide module in an RF particle accelerator includes an unbrazed joint that provides a reliable vacuum seal and RF contact between resonators with precisely controlled internal geometry. The joint can be disassembled and reassembled without degradation. Hard, stainless steel end faces include knife edges pressed into a copper central component, such as a gasket. The knife edges extend the waveguide interiors without gaps or interruptions. The central component serves as a coupling iris or other functional component of the resonant apparatus, thereby allowing the central component to have substantial dimensions that inhibit mechanical distortions thereof. The waveguides and knife edges can be copper plated. Embodiments include embedded passages and/or recesses used for cooling, radiation shielding, magnetic focusing coils, and/or electron optics element formed by permanent magnets.