Gyrotron Whispering Gallery Mode Coupler with Integrated Reflectors
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Solution Overview
Problem
High-power gyrotrons face inefficiencies in RF power transmission due to high-order TE modes, requiring complex mirror adjustments and large diamond apertures, which lead to internal diffraction losses, electron beam interactions, and alignment issues.
Innovation Solution
A launch coupler with a cylindrical input waveguide and step-cut launcher, featuring integrated mode conversion reflectors that transform whispering gallery modes into HE11 modes for efficient coupling into a corrugated output waveguide, reducing the need for external mirrors and large diamond apertures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-order TE modes are used in gyrotrons to generate RF power, then the gyrotron can produce high power output, but the RF power transmission efficiency deteriorates due to high losses in traditional transmission systems
Solution Approach 1:
The invention transforms the RF mode parameters from high-order TE modes to HE11 mode through a mode converter, changing the electromagnetic field distribution characteristics to enable efficient low-loss transmission while preserving the high power generation capability of the gyrotron
Solution Approach 2:
The invention replaces the traditional mechanical mirror-based beam shaping system with a waveguide-based mode conversion system that uses electromagnetic field interactions to transform modes, eliminating the need for adjustable mirrors and complex mechanical alignment systems
2Loss of energy
If traditional quasi-optical launchers with internal mirrors are used for mode conversion, then RF power can be transformed to Gaussian-like profiles, but the device complexity increases due to adjustable mirrors and alignment requirements
Solution Approach 1:
The invention extracts and eliminates the mirror components from the mode conversion system, replacing them with a waveguide-based mode converter that performs the same function without requiring adjustable elements or complex alignment procedures
Solution Approach 2:
The mode converter is designed to automatically perform mode transformation through its fixed geometric structure, eliminating the need for external adjustment mechanisms and making the system self-aligning through the natural electromagnetic field interactions within the waveguide structure
3Reliability
If large diamond apertures are used to couple RF power out of the gyrotron, then the RF beam quality can be maintained, but the cost increases due to expensive diamond material requirements
Solution Approach 1:
The invention changes the RF mode parameters to HE11 mode which has a concentrated field distribution, allowing the use of smaller diamond apertures while maintaining the same RF beam quality and power transmission characteristics
Solution Approach 2:
The HE11 mode has an asymmetric field distribution concentrated near the waveguide wall, which allows for a smaller effective aperture size compared to Gaussian modes, thereby reducing the required diamond window diameter and associated costs
4Productivity
If adjustable mirrors are used in the gyrotron for optimum performance, then the RF power transmission efficiency can be maximized, but the ease of operation deteriorates due to the need for continuous adjustment and alignment
Solution Approach 1:
The invention removes the adjustable mirrors from the system and replaces them with a fixed waveguide mode converter, maintaining high transmission efficiency through electromagnetic field-based mode transformation while eliminating the operational complexity of mirror adjustment and alignment
Solution Approach 2:
The invention substitutes the mechanical mirror adjustment system with an electromagnetic field-based mode conversion system that achieves optimal performance through fixed geometric structures, eliminating the need for operational adjustments and simplifying the ease of operation
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 significantly reduces internal losses, eliminates the need for adjustable mirrors, and minimizes the diameter of the diamond output window, achieving high coupling efficiency and cost savings while maintaining RF beam quality.
Implementation Method 1
a mode converter for a gyrotron having an integrated mode converting first reflector coupled to a quasi-optical launcher comprising a cylindrical input waveguide supporting a Whispering Gallery mode (WG mode or WGM) and having a step cut launcher with a launch edge, the first reflector generating an RF beam with an elliptical radiation pattern and coupling the RF beam into a second mode converting reflector converting the RF beam from the first reflector into an HE11 mode RF beam
Data Source
AI summary
A cylindrical waveguide with a mode converter transforms a whispering gallery mode from a gyrotron cylindrical waveguide with a helical cut launch edge to a quasi-Gaussian beam suitable for conveyance through a corrugated waveguide. This quasi-Gaussian beam is radiated away from the waveguide using a spiral cut launch edge, which is in close proximity to a first mode converting reflector. The first mode converting reflector is coupled to a second mode converting reflector which provides an output free-space HE11 mode wave suitable for direct coupling into a corrugated waveguide. The radiated beam produced at the output of the second mode converting reflector is substantially circular.