Ionization Gauge Feedthrough Insulator Shielding
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Solution Overview
Problem
Hot-cathode ionization gauges, such as Bayard-Alpert gauges, have a limited operational lifetime when exposed to harsh environments like high pressures or certain gas types, leading to electrical leakage and failure due to material deposition on insulators and feedthrough pins.
Innovation Solution
The implementation of shields around electrical feedthrough pins and insulators to prevent material deposition and electrical leakage, using spacers for optical distance and attaching the shields to the feedthrough pins or enclosure, made from materials like ceramic or metallic, to enhance the operational lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the ionization gauge is operated in harsh environments (high pressures or certain gas types), then the gauge can perform measurements in these conditions, but material deposits on the insulator causing electrical leakage and gauge failure
Solution Approach 1:
A shield made of insulating material (ceramic or glass) is introduced as an intermediary component between the harmful environment and the feedthrough pin insulator. The shield captures sputtered material and prevents it from depositing on the insulator, thereby maintaining electrical isolation and extending gauge lifetime while allowing operation in harsh environments
2Device complexity
If no shield is used around the feedthrough pin insulator, then the device structure remains simple, but material deposits on the insulator causing electrical leakage
Solution Approach 1:
The shield serves as a simple intermediary structure that blocks material deposition paths without requiring complex mechanisms. It is attached to the feedthrough pin or enclosure and extends beyond the insulator to capture sputtered material, providing reliable electrical isolation with minimal added complexity
3Reliability
If the shield is placed close to the insulator for effective shielding, then material deposition is prevented, but electrical leakage may occur between the shield and insulator
Solution Approach 1:
The shield itself acts as an insulating barrier between the conductive feedthrough pin and the insulator. By being made of insulating material and positioned close to the insulator, it shields the insulator from material deposition while its own insulating properties prevent electrical leakage paths between the pin and insulator
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
The shields effectively prevent electrical leakage and extend the operational lifetime of the ionization gauge in harsh environments, reducing measurement errors and maintaining vacuum integrity.
Implementation Method 1
The shield is configured to shield the insulator from material that may deposit on the insulator and cause electrical leakage between the electrical feedthrough pin and nearby gauge components. The material may include material from a vacuum process or material sputtered from surfaces of the ionization gauge.
Data Source
AI summary
Shields for feedthrough pin insulators of a hot cathode ionization gauge are provided to increase the operational lifetime of the ionization gauge in harmful process environments. Various shield materials, designs, and configurations may be employed depending on the gauge design and other factors. In one embodiment, the shields may include apertures through which to insert feedthrough pins and spacers to provide an optimal distance between the shields and the feedthrough pin insulators before the shields are attached to the gauge. The shields may further include tabs used to attach the shields to components of the gauge, such as the gauge's feedthrough pins. Through use of example embodiments of the insulator shields, the life of the ionization gauge is extended by preventing gaseous products from a process in a vacuum chamber or material sputtered from the ionization gauge from depositing on the feedthrough pin insulators and causing electrical leakage from the gauge's electrodes.