Microwave Plasma Waveguide Structure Without Inner Conductor
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Solution Overview
Problem
Conventional plasma generating apparatuses face issues such as dielectric breakdown, heat accumulation, and high manufacturing costs due to their coaxial tube structure, which limits plasma output and size reduction.
Innovation Solution
A plasma generating apparatus with a conductive waveguide structure that lacks an inner conductor, using dielectric members to propagate microwaves and generate plasma, ensuring adequate insulation distance and efficient heat dissipation while maintaining impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coaxial tube structure with an inner conductor is used, then plasma can be generated, but the insulation distance is limited and dielectric breakdown occurs easily
Solution Approach 1:
The invention removes the inner conductor from the coaxial tube structure, extracting the problematic element that limited the insulation distance. By eliminating the inner conductor, the design achieves sufficient insulation distance without the risk of dielectric breakdown that plagued the conventional coaxial structure.
2Productivity
If microwave output is increased to generate high output plasma, then plasma productivity improves, but dielectric breakdown occurs more easily
Solution Approach 1:
By removing the inner conductor that constrained the insulation distance, the system can safely handle higher microwave outputs without experiencing dielectric breakdown, thereby enabling high-output plasma generation while maintaining reliability.
3Reliability
If the outer shield radius is increased to ensure sufficient insulation distance, then dielectric breakdown is prevented, but the apparatus size increases
Solution Approach 1:
The removal of the inner conductor allows the outer shield radius to be reduced while maintaining sufficient insulation distance, thereby reducing the overall apparatus size without compromising dielectric breakdown prevention.
4Temperature
If heat is released efficiently from the central core, then temperature control improves, but the contact area between central core and outer shield must be increased
Solution Approach 1:
By eliminating the central core, the invention removes the heat dissipation problem entirely. The dielectric member that replaces the central core does not generate Joule heat, thus eliminating the need for complex heat dissipation structures and large contact areas.
5Use of energy by moving object
If a tapered outer surface of the dielectric body is used to improve impedance matching, then microwave transmission efficiency improves, but manufacturing complexity and cost increase
Solution Approach 1:
The removal of the inner conductor simplifies the overall structure, allowing for easier manufacturing of the dielectric member while maintaining effective impedance matching through the simplified geometry.
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 apparatus achieves enhanced plasma output and reduced size by preventing dielectric breakdown and heat accumulation, while minimizing manufacturing costs through improved impedance matching and versatility in plasma processing applications.
Implementation Method 1
a first dielectric member extending along a main axis of the waveguide in an interior of the waveguide, connected to a microwave supply cable that supplies microwaves, and configured to propagate the supplied microwaves to the first end side
Implementation Method 2
a second dielectric member arranged so as to close the opening and configured to generate plasma with use of the microwaves propagated by the first dielectric member
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Provided are an outer conductor 29 as a conductive waveguide having an opening 34 at a first end, a first dielectric 31 extending along a main axis of the outer conductor 29 in an interior of the outer conductor 29, connected to a microwave supply cable 5 that supplies microwaves, and configured to propagate the supplied microwaves to the first end side, and a second dielectric 33 arranged so as to close the opening 34 and configured to generate plasma with use of the microwaves propagated by the first dielectric 31.