Plasma Generator With Recessed Electrodes For Uniform Treatment
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Solution Overview
Problem
Existing atmospheric plasma generators face challenges with unstable electric discharge and non-uniform plasma density, particularly when treating large areas, due to short inter-electrode distances and the use of wide electrodes, which limits their effectiveness in applications like plasma treatment of liquid-crystal panels.
Innovation Solution
A plasma generator with a longitudinal columnar plasma-generating zone defined by an insulator casing, featuring a pair of electrodes with a controlled spacing and plasma-generating gas inlets and outlets, allowing for stable linear electric discharge and increased plasma volume, enabling uniform plasma treatment over a wide area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If wide electrodes are used to treat large areas, then the treatment area is increased, but plasma density uniformity deteriorates
Solution Approach 1:
The electrode surface is divided into multiple small recesses (micro-scale hollow cathodes) distributed across the wide electrode. Each recess acts as an independent plasma generation point, ensuring uniform plasma distribution across the entire large treatment area while maintaining consistent plasma density at each segment.
Solution Approach 2:
The electrode structure incorporates localized micro-scale recesses with specific dimensions (depth and diameter) that create optimal conditions for hollow cathode discharge. This local structural modification ensures uniform plasma generation across the entire electrode surface, preventing spot-like discharge and maintaining consistent plasma density throughout the large treatment area.
2Quantity of substance
If short inter-electrode distance is used, then plasma density is increased, but electric discharge stability deteriorates
Solution Approach 1:
The invention optimizes the inter-electrode distance to a specific range (1-10 mm) that balances plasma density and discharge stability. Additionally, the micro-scale recesses in the electrodes create localized high-density plasma regions while the overall electrode configuration maintains stable discharge across the entire gap, resolving the contradiction between density and stability.
3Reliability
If long inter-electrode distance is used, then electric discharge stability is improved, but plasma density decreases
Solution Approach 1:
The electrode surface is divided into multiple small recesses (micro-scale hollow cathodes) distributed across the wide electrode. Each recess acts as an independent plasma generation point, ensuring uniform plasma distribution across the entire large treatment area while maintaining consistent plasma density at each segment.
Solution Approach 2:
The electrode structure incorporates localized micro-scale recesses with specific dimensions (depth and diameter) that create optimal conditions for hollow cathode discharge. This local structural modification ensures uniform plasma generation across the entire electrode surface, preventing spot-like discharge and maintaining consistent plasma density throughout the large treatment area.
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 configuration stabilizes plasma generation, achieving consistent linear plasma flow and enabling effective plasma treatment of large areas without spot-like discharge issues, enhancing the generator's applicability to various treatment objects.
Implementation Method 1
a casing which is made of an insulator and which defines a longitudinal columnar plasma-generating zone
Implementation Method 2
electrode surfaces facing each other are provided with micro-scale recesses, to thereby induce hollow cathode electric discharge, through which a plasma is generated
Implementation Method 3
a plasma-generating gas inlet for supplying a plasma-generating gas to the plasma-generating zone
Implementation Method 4
outlets for jetting a gas containing at least plasma in a direction normal to the longitudinal direction of the plasma-generating zone
Data Source
AI summary
To provide a plasma generator having plasma-generating zone of increased volume.A plasma generator 110 has a cylindrical casing 11 made of a sintered ceramic produced from alumina (Al2O3) as a raw material. The casing 11 has a slit-like gas inlet 11i and a plurality of cylindrical gas outlets 11o. From the gas inlet 11i to the top of the plasma-generating zone P, the slit width (the front-to-back direction with respect to the sheet of FIG. 2.A, and the left-to right direction in FIG. 2.B) is adjusted to 1 mm, and gas outlets 11o each having an inner diameter of 1 to 2 mm are formed in straight line along the longitudinal direction of the plasma-generating zone P. The plasma-generating zone P has a square cross-section normal to the longitudinal direction having a side of 2 to 5 mm. Each of the surfaces of the electrodes 2a, 2b facing each other has a plurality of recesses (hollow portions). An elevated voltage of about 9 kV obtained from a commercial AC voltage (60 Hz, 100 V) was applied to the electrodes 2a, 2b, to thereby supply a current of 20 mA. When argon gas was supplied through the gas inlet 11i, even in the case where the electrodes 2a, 2b were separated at a spacing of 4 cm, stable linear electric discharge was observed.