RF Feedthrough Insulative Cone for Ion Beam Acceleration
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Solution Overview
Problem
Ion implantation systems face challenges in extending the lifetime of RF resonators and preventing gas leakage from the resonator into the high-vacuum environment, due to cracking and degradation of ceramic cones and o-rings, which leads to high voltage sparking and plasma ignition.
Innovation Solution
An improved RF feedthrough design featuring an electrically insulative cone with a tapered sidewall, a padding cap, and metallized surfaces, along with metal shorting strips and a flange configuration, which prevents line-of-sight access and reduces electrical discharges, and uses ceramic materials like alumina or quartz to minimize thermal expansion and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a conventional RF feedthrough design is used, then the structure is simple, but cracking and degradation of ceramic cones occur leading to shortened lifetime
Solution Approach 1:
The feedthrough structure is divided into multiple functional segments: an electrically insulative cone, a flange, a stem, and a padding cap. Each segment performs a specific function - the cone provides electrical insulation, the flange enables mounting, the stem transmits RF signals, and the padding cap blocks sputtered material. This segmentation allows optimization of each component for its specific function, improving overall reliability and lifetime.
Solution Approach 2:
The padding cap is positioned in advance to block the line-of-sight path from the vacuum chamber to the inner surface of the cone, preventing sputtered material from reaching and degrading the ceramic cone before damage can occur. This preliminary protective action extends the lifetime of the feedthrough by preventing cracking and degradation proactively.
2Reliability
If conventional feedthrough design is used, then manufacturing is simple, but gas leakage occurs due to degradation of sealing components
Solution Approach 1:
The feedthrough employs composite construction combining electrically insulative ceramic materials (alumina or quartz) for the cone with metal components (flange, stem, padding cap). The ceramic provides electrical insulation and chemical inertness, while the metal components provide mechanical strength and sealing surfaces. This composite approach enhances vacuum seal integrity by using materials optimized for their specific functions.
Solution Approach 2:
The flange acts as an intermediary component between the vacuum chamber wall and the feedthrough assembly, providing a sealed mounting interface. The stem serves as an intermediary transmitting RF signals while being electrically insulated from the chamber wall by the cone. These intermediary elements protect the vacuum seal from direct exposure to high voltage and sputtered material.
3Reliability
If conventional feedthrough design is used, then high voltage generation is achieved, but electrical discharges and sparking occur
Solution Approach 1:
The electrically insulative cone serves as a mediator between high voltage components, providing electrical insulation that prevents direct contact and potential sparking. The stem, also insulated by the cone, transmits RF signals while being electrically isolated from the chamber wall. This intermediary insulation structure stabilizes high voltage operation by preventing electrical discharges.
Solution Approach 2:
The padding cap is positioned in advance to block sputtered material from reaching the high voltage regions and insulating surfaces. By preventing contamination of the ceramic cone and metal interfaces before electrical breakdown can occur, this preliminary action maintains high voltage stability and prevents sparking.
4Duration of action of stationary object
If conventional feedthrough design is used, then assembly is straightforward, but sputtered material degrades components
Solution Approach 1:
The padding cap is installed in advance to block the line-of-sight path from the vacuum chamber to the inner surface of the cone, preventing sputtered material from reaching and degrading the ceramic cone. This preliminary protective barrier extends component lifetime by stopping material deposition before it can cause cracking or degradation.
Solution Approach 2:
The feedthrough is segmented into distinct components with the padding cap as a separate protective element. This segmentation allows the padding cap to specifically address the sputtering problem without requiring redesign of the entire feedthrough structure, extending component lifetime through targeted protection.
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 solution effectively prevents cracking, punch-through holes, and gas leakage, while maintaining high voltage stability and extending the lifetime of RF resonator components by blocking sputtered material and reducing electrical discharges, thus enhancing the vacuum environment's integrity.
Implementation Method 1
The electrically insulative cone and flange are configured to pass the stem through the hole in the wall of the chamber while electrically insulating the stem from the wall of the chamber
Implementation Method 2
blocking sputtered material and reducing electrical discharges
Data Source
AI summary
An RF feedthrough has an electrically insulative cone that is hollow having first and second openings at first and second ends having first and second diameters. The first diameter is larger than the second diameter, defining a tapered sidewall of the cone to an inflection point. A stem is coupled to the second end of the cone, and passes through the first opening and second opening. A flange is coupled to the first end of the cone and has a flange opening having a third diameter. The third diameter is smaller than the first diameter. The stem passes through the flange opening without contacting the flange. The flange couples the cone to a chamber wall hole. Contact portions of the cone may be metallized. The cone and flange pass the stem through the hole while electrically insulating the stem from the wall of the chamber.