Plasma Generator With Hollow Cathode Electrodes for Stable Discharge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing atmospheric plasma generators face instability in electric discharge at short inter-electrode distances, leading to non-uniform plasma density and limited effective use for treating large areas, such as liquid-crystal panels, due to the difficulty in maintaining uniform plasma generation over elongated zones.
Innovation Solution
The design incorporates a gas discharge section with tapered or stepwise diameter holes, a diffusion section with guide portions for uniform gas distribution, and electrodes with recessed surfaces to stabilize plasma generation, allowing for a longer plasma-generating zone and preventing electric discharge to the treatment object, thereby ensuring uniform radical irradiation and preventing UV damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If long electrodes are provided to face each other to extend the plasma-generating zone in the longitudinal direction, then the plasma-generating zone volume is increased, but uniformity in plasma density is impaired
Solution Approach 1:
The gas discharge section is divided into multiple segments along the longitudinal direction, with each segment having holes at different positions. This segmentation allows independent control of plasma generation in different zones, maintaining uniform plasma density while extending the overall plasma-generating zone volume.
Solution Approach 2:
Holes are strategically positioned at different locations along the longitudinal direction of the gas discharge section, creating local variations in gas discharge characteristics. This local quality approach ensures uniform plasma distribution across the extended zone by optimizing discharge conditions in each specific region.
2Quantity of substance
If short inter-electrode distance is employed, then high-density plasma can be generated, but electric discharge becomes unstable
Solution Approach 1:
Hollow cathode structures are formed on the electrode surfaces before plasma generation begins. These pre-formed hollow cathodes create stable electric field distribution and facilitate reliable electric discharge initiation, enabling stable high-density plasma generation at short inter-electrode distances.
Solution Approach 2:
The hollow cathode structures act as intermediaries between the electrodes and the plasma-generating gas. They mediate the electric discharge process by concentrating and stabilizing the electric field, enabling reliable plasma generation at short inter-electrode distances where direct discharge would be unstable.
3Productivity
If the tips of holes are close to the treatment object, then strong treatment effect is achieved, but electric discharge occurs between gas discharge section and treatment object
Solution Approach 1:
The harmful electric discharge is extracted and confined to occur only at the electrode surfaces within the plasma-generating zone. The hole structure design ensures that gas discharge occurs primarily at the electrode-hole interface rather than between the hole tips and treatment object, eliminating discharge damage while maintaining treatment effectiveness.
Solution Approach 2:
The holes serve as intermediaries that guide and control the plasma-generating gas flow. They mediate between the plasma generation zone and the treatment object, allowing strong treatment effect through optimized gas delivery while preventing direct electric discharge to the treatment object by confining discharge to the electrode-hole interface.
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 enables effective generation of stable, high-density plasma over elongated zones, allowing for efficient surface treatment of large areas without damaging the object, with optimized radical distribution and minimized UV exposure.
Implementation Method 1
electrode surfaces facing each other are provided with microscale recesses, to thereby induce hollow cathode electric discharge, through which a plasma is generated
Implementation Method 2
the plasma-generating gas is caused to pass through the plasma-generating zone, a gas containing at least a plasma can be jetted... preventing UV damage
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
To provide a plasma generator having a plasma-generating zone of an increased volume. A plasma generator 100 has a casing 10 made of a sintered ceramic produced from alumina (Al2O3) as a raw material. The casing 10 has a slit-like gas intake section 12, and a gas discharge section 20 in which a plurality of holes are disposed in a line. From the gas intake section 12 to the top of a plasma-generating zone P, the slits have a width of 1 mm. There is provided a second gas discharge section 22 including holes 24 which have a diameter of 0.5 mm and a length of 16 mm and which are arranged in a line along the longitudinal axis of the plasma -generating zone P. The plasma-generating zone P has a cross-section which is a rectangle having a side of 2 to 5 mm. Electrodes 2a, 2b are provided with hollow portions on the surfaces thereof facing each other. A power sources supplies about 9 kV, which is obtained by boosting 100 V (60 Hz) and is applied to the electrodes 2a, 2b with a current of 20 mA. When argon gas is supplied through a gas intake section 18, a plasma was generated, even when the electrodes 2a, 2b were separated at a maximum spacing of 4 cm. No electric discharge was generated between the tips of the holes 24 and a treatment object.