Coaxial Microwave Plasma Torch Geometry for Stable Plasma
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional coaxial microwave plasma torches suffer from destabilization of plasma and a shortened lifetime of the discharge antenna due to localized electric field concentration at the tip end, leading to erosion and melting.
Innovation Solution
The discharge antenna tip end is formed in a hemispherical shape, and the counter electrode tapers towards the plasma outlet, with both surfaces dielectric-coated, ensuring uniform electric field distribution and protection against plasma-induced damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the tip end of the discharge antenna is formed with a pointed shape or flat cut shape, then the electric field concentrates at the tip end, but this causes localized erosion and melting leading to plasma destabilization and shortened antenna lifetime
Solution Approach 1:
The tip end of the discharge antenna is formed with a hemispherical shape instead of a pointed or flat cut shape. This curvature distributes the electric field more uniformly across the tip surface, preventing localized concentration that causes sputtering and melting, thereby maintaining plasma stability and extending antenna lifetime while still achieving sufficient electric field strength for plasma generation
2Power
If the tip end of the discharge antenna is formed with a pointed shape or flat cut shape, then the electric field concentrates at the tip end, but this causes localized heating and melting leading to shortened antenna lifetime
Solution Approach 1:
The hemispherical shape of the discharge antenna tip distributes thermal load and electric field stress uniformly across the surface, preventing localized overheating and melting. This geometric modification significantly extends the operational lifetime of the antenna while maintaining effective plasma generation capability
Solution Approach 2:
The discharge antenna tip is coated with a dielectric material that provides protective functionality. This coating layer protects the underlying antenna material from plasma-induced erosion and thermal damage, thereby extending antenna lifetime while allowing the hemispherical geometry to maintain uniform electric field distribution
3Device complexity
If the counter electrode has a parallel structure, then the structure is simple, but the electric field distribution is non-uniform leading to plasma instability
Solution Approach 1:
The counter electrode incorporates a tapered portion that curves toward the discharge antenna tip, creating a more uniform electric field distribution in the plasma generation region. This curved geometry complements the hemispherical antenna tip to achieve uniform field distribution, improving plasma stability without excessive structural complexity
Solution Approach 2:
The counter electrode features a localized tapered portion specifically positioned to face the discharge antenna tip, while the rest of the electrode maintains a simpler structure. This localized geometric modification concentrates the field-uniformizing effect where it is most needed, achieving plasma stability with minimal additional complexity
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
Stable generation of uniform and high-density plasma with extended lifetime of the discharge antenna and counter electrode, achieved through uniform electric field distribution and dielectric coating.
Implementation Method 1
the tip end of the discharge antenna and the surface of the counter electrode that faces the discharge antenna are dielectric-coated
Implementation Method 2
an electric field is irradiated uniformly and stably from the tip end of the discharge antenna into a localized area between the tip end and the counter electrode
Implementation Method 3
a microwave input portion provided near a base end of the discharge antenna
Implementation Method 4
the electric field of the microwaves concentrates at the tip end of the discharge antenna, creating a high electric field that induces plasma generation
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Included are a body 1 having a coaxial structure consisting of a discharge antenna 2 situated inside and a counter electrode 3 situated outside, a microwave input portion 4 provided near a base end of the discharge antenna in the body, a plasma generation portion 6 provided near a tip end 2a of the discharge antenna in the body and communicating with a plasma outlet 5, and a gas supply portion 7 configured to supply the plasma generation portion with gas. The tip end of the discharge antenna is formed in a hemispherical shape, and the counter electrode is formed with a portion that faces the tip end of the discharge antenna tapering toward the plasma outlet.