Bi-metallic Cable Termination for Vacuum Hermetic Sealing

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Solution Overview

Problem

Standard semi-rigid coaxial cables are not hermetic and thus cannot be used in vacuum environments due to outgassing, which contaminates the vacuum and compromises electrical performance, while hermetic solutions are not readily available for high-performance applications.

Innovation Solution

A cable end termination featuring a tubular bi-metallic body with different thermal expansion metals and a dielectric body to create a hermetic seal for the coaxial cable, allowing the use of non-hermetic connectors and maintaining high electrical performance in vacuum environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a standard semi-rigid coaxial cable is used in a vacuum environment, then electrical performance is maintained, but the cable is not hermetic and causes contamination through outgassing

Engineering Contradiction:

Improveelectrical performanceVSAvoidvacuum contamination

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The cable system is divided into two distinct segments: a non-hermetic coaxial cable portion that maintains electrical performance, and a hermetic termination portion that prevents vacuum contamination. The termination includes a hermetic seal assembly with a flange, seal, and connector housing that isolates the cable's dielectric layer from the vacuum environment while allowing electrical connections to be made through the seal.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A hermetic seal assembly acts as an intermediary between the non-hermetic coaxial cable and the vacuum environment. This intermediary component includes a hermetic flange with a seal that creates a barrier, allowing the cable to maintain its electrical performance while preventing outgassing from contaminating the vacuum. The seal assembly mediates between the conflicting requirements of electrical performance and vacuum compatibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If a hermetic bulkhead connector with seal is used to terminate a non-hermetic cable, then vacuum integrity is improved, but the non-hermetic cable still outgasses and contaminates the vacuum environment

Engineering Contradiction:

Improvevacuum integrityVSAvoidoutgassing

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The hermetic seal function is extracted from the cable itself and placed into a separate termination assembly. This allows the cable to remain a standard non-hermetic coaxial cable with good electrical performance, while the termination assembly provides the hermetic barrier. The seal is taken out of the cable construction and implemented as a separate component that interfaces with the cable through a flange connection.

Inventive Principle:

Principle #2Taking out (Extraction)

3Object-affected harmful factors

If a hermetic cable is fabricated using methods and materials that prevent outgassing, then vacuum compatibility is improved, but electrical performance is degraded

Engineering Contradiction:

Improvevacuum compatibilityVSAvoidelectrical performance

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

Different parts of the cable system have different properties: the cable portion uses standard materials and construction for optimal electrical performance, while the termination portion uses hermetic materials and construction for vacuum compatibility. The flange, seal, and connector housing are designed specifically for hermetic sealing, while the coaxial cable itself maintains standard electrical characteristics. This local differentiation allows each component to optimize for its specific function.

Inventive Principle:

Principle #3Local 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

Enables the use of standard coaxial cables in vacuum environments without compromising electrical performance, providing a hermetic seal that prevents contamination and allows for connections using commercially available non-hermetic connectors.

Implementation Method 1

a second longitudinal portion joined with the first longitudinal portion and comprising a second metal having a different coefficient of thermal expansion (CTE) than the first metal

Methodology Applied

Scientific EffectCoefficient of thermal expansion (CTE): Thermal Expansion

Data Source

PatentUS9768543B2Cable end termination including cable dielectric layer hermetic seal and related methods

Publication Date: 2017.09.19 WINCHESTER INTERCONNECT HERMETICS LLC

AI summary

A cable end termination is for a coaxial cable that includes inner and outer conductors and a dielectric layer therebetween that is subject to outgassing in a vacuum environment. The cable end termination may include a tubular bi-metallic body that includes a first longitudinal portion including a first metal and a second longitudinal portion joined with the first longitudinal portion and that includes a second metal having a different coefficient of thermal expansion (CTE) than the first metal. The tubular bi-metallic body may have a first end receiving the coaxial cable and a second end opposite the first end that carries a dielectric body to define a hermetic seal for the dielectric layer in the vacuum environment. A center pin contact may extend through the dielectric body, and a center conductor contact may couple the center pin contact to the inner conductor.