Coaxial Waveguide Gas Pipe Shielding for Stable Plasma Coupling
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Solution Overview
Problem
Existing plasma processing apparatuses face issues with discharge within gas pipes crossing coaxial waveguides, leading to a decrease in power transmittance of electromagnetic waves and mode correction challenges in these waveguides.
Innovation Solution
The apparatus includes a coaxial waveguide with metal conductor parts crossing it, surrounded by filters to prevent electromagnetic wave propagation, and a shower head with gas holes, along with a dielectric introducer to introduce electromagnetic waves, thereby preventing discharge and maintaining power transmittance while correcting the electromagnetic wave mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a gas pipe crosses the coaxial waveguide, then gas can be supplied to the shower head, but discharge occurs within the gas pipe and power transmittance decreases
Solution Approach 1:
A dielectric member is introduced as an intermediary substance filling the inner conductor of the coaxial waveguide. This dielectric member enables the gas pipe to cross the waveguide while preventing discharge by providing electrical insulation, thus maintaining power transmittance while allowing gas supply functionality
Solution Approach 2:
The gas pipe is nested within the inner conductor of the coaxial waveguide structure. The dielectric member surrounds the gas pipe inside the inner conductor, creating a nested configuration where the gas pipe is protected by the dielectric insulation while passing through the waveguide
2Ease of operation
If a gas pipe crosses the coaxial waveguide, then gas can be supplied, but the mode of electromagnetic waves becomes incorrect
Solution Approach 1:
The dielectric member acts as a mediator that maintains the electromagnetic field distribution within the coaxial waveguide. By providing consistent dielectric properties around the gas pipe, it ensures that the TEM mode of electromagnetic waves is preserved despite the presence of the gas pipe crossing the waveguide
3Reliability
If a dielectric member is used to prevent discharge, then power transmittance is maintained, but the structure becomes more complex
Solution Approach 1:
The dielectric member is merged with the existing coaxial waveguide structure, forming an integrated component. The dielectric member becomes part of the waveguide's inner conductor assembly, combining the functions of electrical insulation and structural support without requiring separate complex insulation systems
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 configuration effectively prevents discharge within gas pipes, maintains high power transmittance of electromagnetic waves, and corrects the wave mode to a TEM mode, enhancing the plasma processing efficiency.
Implementation Method 1
The VHF waves propagate from the coaxial waveguide to the transmitter, and then propagate radially in the transmitter
Implementation Method 2
The one or more filters are configured to prevent the electromagnetic waves from propagating around the one or more conductor parts
Implementation Method 3
the plasma processing apparatus configured to generate plasma using VHF waves
Data Source
AI summary
In a disclosed plasma processing apparatus, a metallic gas pipe extends in a direction crossing a coaxial waveguide and is connected to an inner conductor of the coaxial waveguide between one end and the other end of the inner conductor. The gas pipe is connected to a gas flow path of the inner conductor. The plasma processing apparatus includes a filter configured to prevent electromagnetic waves from propagating around the gas pipe. The filter includes a cylindrical cover conductor provided to surround the gas pipe. The cover conductor includes one end connected to an outer conductor of the coaxial waveguide and the other end that is a short-circuit end connected to the gas pipe.