Vacuum Electron Device Output Window with Venting Means
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Solution Overview
Problem
Conventional spaced triple layer output windows for vacuum electron devices are prone to dimensional variations and mode conversion issues during manufacturing, leading to suboptimal broadband performance and risk of vacuum bond failure due to trapped volumes and differential expansion between ceramic and copper materials.
Innovation Solution
The output window design features an intermediate dielectric layer with upper and lower layers supported by corbels and pillars, allowing for simultaneous brazing and venting, which simplifies manufacturing and maintains microwave performance by avoiding trapped volumes and mode conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional spaced triple layer window design is used, then broadband performance is improved, but manufacturing precision deteriorates due to dimensional variations and tilt between ceramic discs
Solution Approach 1:
The patent introduces an intermediate layer of dielectric material between the upper and lower ceramic layers. This intermediate layer acts as a mediator that simplifies the assembly process by providing a stable mounting surface, reducing the need for precise alignment between the outer ceramic layers, and thereby improving manufacturing precision while maintaining broadband performance.
Solution Approach 2:
The window assembly is segmented into three distinct dielectric layers (upper, intermediate, and lower) that can be manufactured and prepared separately. This segmentation allows each layer to be optimized independently and assembled with greater ease, reducing the cumulative dimensional variations that would occur in a monolithic structure.
2Reliability
If conventional brazing process is used, then vacuum-tight seal is achieved, but reliability deteriorates due to trapped volumes causing vacuum bond failure
Solution Approach 1:
The patent extracts or removes the harmful trapped volumes by incorporating venting channels or pathways within the intermediate layer. These venting features allow gases or vapors to escape during the brazing process, preventing the formation of vacuum bonds over trapped volumes and thereby ensuring reliable vacuum sealing.
3Ease of manufacture
If copper tubes are brazed together to form waveguide, then assembly is completed, but device complexity increases due to multiple brazing joints
Solution Approach 1:
The patent merges the upper and lower ceramic layers with the intermediate layer into a more integrated assembly. The intermediate layer is designed to interface with both outer layers in a way that reduces the number of separate brazing joints required, thereby simplifying the overall manufacturing process while maintaining the structural integrity of the waveguide assembly.
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 design ensures a 20% bandwidth with better than -20 dB return loss, reducing the risk of assembly-induced mode conversion and maintaining optimal performance by carefully managing material expansion and assembly tolerances.
Implementation Method 1
the output window normally consists of one or more layers of dielectric, at least one of which will be joined to the device's output waveguide in a vacuum-tight bond, usually achieved by brazing the dielectric to the metal waveguide
Implementation Method 2
the bandwidth performance of a single half-wavelength-thick window design can be improved via the use of quarter wavelength transformers abutting the two faces of the window in order to match the window impedance to the free space impedance
Implementation Method 3
the differential expansion between the copper and ceramic materials require significant recess depths to be employed
Data Source
AI summary
An output window for a vacuum electron device comprises an output waveguide, an intermediate layer of dielectric material joined to the interior of the output waveguide with a vacuum-tight seal, and upper and lower layers of dielectric material spaced apart from the intermediate layer and arranged above and below, respectively, the intermediate layer in a vertical orientation of the output waveguide. The upper and lower layers including openings. Supports extend inwardly into the output waveguide and support the upper and lower layers. Pillars extend through the openings in the lower layer and support the intermediate layer. The openings in the upper and lower layers permit a venting of a region between the upper layer and the intermediate layer and a region between the lower layer and the intermediate layer during the sealing of the intermediate layer while the intermediate layer is supported by the pillars.