A portable plasma device for multiscale surface modification

Abstract

The application provides a portable plasma device for multi-scale surface modification, which is formed by parallel connection of multiple plasma device units, and left and right sides of the plasma device units are respectively provided with side ears and clamping grooves; the two sides of the plasma device body are provided with same medium pipes with one end longer than the side width and sealed; electrodes are arranged in each medium pipe; from one side of the plasma to the other side, high-voltage electrodes and low-voltage electrodes are arranged alternately and are tungsten rods [Z1]. The application realizes flexible splicing of the plasma brush to adapt to different sizes of the processed objects, and greatly increases the applicability of the plasma source. The plasma is generated by using a double dielectric barrier reactor structure, and a uniform plasma plume can be generated under atmospheric pressure by optimizing the electrode and gas path structure; the active substances are transported to the object surface by the airflow to achieve the purpose of surface treatment, and different geometric objects can be processed.

Description

Technical Field

[0001] This invention belongs to the field of plasma devices and relates to a portable plasma device for multi-scale surface modification. Background Technology

[0002] Insulating materials have a wide range of applications in the electrical and electronics industries. However, most insulating materials have low surface energy and a low content of polar groups, resulting in low surface tension, poor hydrophilicity, and poor adhesion, which limits their application range. Therefore, surface modification methods are commonly used to improve the surface properties of insulating materials and expand their application scope. Currently, the main methods used for surface modification of insulating materials include wet chemical methods, ultraviolet irradiation methods, ion beam irradiation methods, and low-temperature plasma treatment methods. Among these, low-temperature plasma modification has advantages over other modification methods, such as simple processing conditions, low energy consumption, short processing time, high efficiency, and no pollution.

[0003] Dielectric barrier discharge (DBD) plasma-mediated surface modification of materials is a process involving the interaction between DBD plasma and the material surface, encompassing both plasma physics and plasma chemistry. The DBD discharge space contains a large number of diverse active particles. On one hand, these particles interact with the polymer material surface, breaking surface chemical bonds and generating free radicals. The average electron energy during DBD discharge is 1–10 eV, sufficient to open most chemical bonds on the insulating material surface. On the other hand, the reopened chemical bonds recombine, causing surface etching, cross-linking, or interaction with reactive active particles in the DBD plasma (such as atoms O, OH, and H₂O), introducing new functional groups and thus improving the material's surface properties. Therefore, DBD plasma-mediated surface modification of insulating materials can be considered as the process by which various active particles in the plasma collide with the material surface, triggering further reactions of macromolecular free radicals during energy exchange, introducing new functional groups and removing smaller molecules, leading to improved surface properties. It is worth noting that the DBD plasma generated by inert gas does not contain reactive particles. Therefore, when using inert gas DBD to modify the surface of materials, the introduction of surface groups is mainly due to the combination of macromolecular free radicals generated by the plasma on the surface of the material with substances in the air or the medium added during the interaction when the material is placed in the air after being treated by DBD plasma.

[0004] The plasma brush mentioned in CN102448239B has a fixed processing size, resulting in low efficiency and slow processing speed for larger objects. Even the plasma brush array mentioned in CN203407057U is just an extension of two plasma brushes. Although it increases the processing size, it is still a fixed-size processing method, making it difficult to flexibly adjust the processing size according to the size of the object to be processed.

[0005] The jet technology mentioned in CN106851954A and CN206024220U has a limited processing area and is not suitable for surface treatment of large-area objects.

[0006] Existing planar plasma treatment technology is mainly used for processing thin film materials due to the small spacing between high and low voltage electrodes. It cannot process the surface of objects with irregular structures and large volumes. Summary of the Invention

[0007] 1. The technical problem to be solved:

[0008] How can plasma devices for surface treatment applications simultaneously meet the dual requirements of handling large-sized objects and having no restrictions on the shape of the objects being treated?

[0009] 2. Technical Solution:

[0010] To address the above problems, this invention provides a portable plasma device for multi-scale surface modification, comprising multiple plasma device units connected in parallel. The device is characterized by: side ears and slots on the left and right sides of each plasma device unit, which fit perfectly together; an internal cavity with an air inlet and an air outlet at each end; identical quartz glass tubes, one end longer than the side width and sealed, located along the sides of the plasma device body and at the connection points of the plasma device units; and electrodes within each quartz glass tube, with high-voltage and low-voltage electrodes alternately arranged from one side of the plasma to the other, the electrodes being made of tungsten rods.

[0011] A rectangular notch is provided at the brush outlet of the plasma device body.

[0012] Both the first and second quartz glass tubes are encased in rubber shells.

[0013] The first quartz glass tube has a rubber outer shell inlaid with wires. The first electrode is connected to the wires by welding, and the tube is connected to the power supply through a power cord plug.

[0014] The power supply uses a conventional microsecond pulse power supply.

[0015] The air inlet is provided with two air inlets.

[0016] Each plasma device unit has a wedge-shaped internal air passage, with the inlet channel being wider than the outlet channel.

[0017] At the junction of the plasma unit units, the quartz glass tube is exposed in the cavity of the two adjacent plasma unit units.

[0018] A flow equalization plate is provided inside the cavity, and the flow equalization plate has multiple openings.

[0019] 3. Beneficial effects:

[0020] This invention optimizes the design of the plasma reactor and gas duct structure to form a brush-shaped plasma plume at the reactor outlet. Multiple plasma brushes can be flexibly configured and used according to actual needs to address the issue of excessively small processing dimensions. By adjusting the discharge operating parameters, a stable discharge can be achieved, and the plasma plumes formed by different reactors connected in parallel can merge into a single processing area. This allows for the formation of a regular rectangular brush-shaped plasma plume under a multi-brush configuration, acting on the surface to be treated, thus enabling surface treatment of insulators and other insulating materials. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a single plasma device.

[0022] Figure 2 This is a schematic diagram of the connection structure between two plasma devices.

[0023] Figure 3 This is a structural diagram of the electrode structure of the plasma device.

[0024] Figure 4 This is a detailed map of the exposed export area.

[0025] Figure 5 It shows an overall view of the plasma and a schematic diagram of the plasma plume.

[0026] Figure 6 This is a side view of a single cavity in a plasma device.

[0027] Figure 7 This is a schematic diagram of the flow equalization plate structure.

[0028] Figure 8 This is a block diagram of a plasma processing device system.

[0029] Figure 9 These are simulation diagrams of the plasma flow field, where (a) is the simulated flow field without a flow equalizer, and (b) is the simulated flow field with a flow equalizer.

[0030] Figure 10 It is a light emission image of two parallel plasma devices.

[0031] Figure 11 This is a spectrum of two plasma devices connected in parallel.

[0032] Explanation of reference numerals in the attached diagram: 1. Side ear; 2. Slot; 3. Connection; 4. Electrode; 5. Air inlet; 6. Quartz glass tube; 7. Outlet splicing position; 8. Quartz glass tube position at the connection; 9. Plasma plume; 10. Flow equalization plate; 11. Rubber shell; 12. High voltage insulated wire; 13. Wire plug; 14. Air passage. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] A portable plasma device for multi-scale surface modification, consisting of multiple plasma device units connected in parallel, such as... Figure 1 As shown, the plasma device unit has side ears 1 and slots 2 on its left and right sides respectively. The side ears 1 and slots 2 can fit together perfectly, as shown. Figure 2 As shown, two plasma device units are connected in parallel at the connection point 3 via side ears 1 and slots 2. This parallel connection reduces the distance between the outlets, thus reducing the distance between the plasma plumes from the different plasma channels, allowing the expanded plasma plumes to merge into a single mass. The number of brushes can also be flexibly adjusted according to the size of the object being treated, increasing the applicability of the plasma brushes.

[0035] The plasma device unit has a hollow interior, with an air inlet on the front and an outlet on the back. The air inlet blows the plasma generated at the outlet out of the plasma brush to form a plasma plume.

[0036] In one embodiment, the air inlet is provided with two air inlets 5, which can make the gas more uniform.

[0037] like Figure 3 As shown, both sides of the plasma device body and the connection point of the plasma device unit are provided with identical quartz glass tubes 6, which are longer than the width of the side and sealed at one end. Each quartz glass tube 3 is provided with an electrode, and high-voltage electrodes and low-voltage electrodes are alternately arranged from one side of the plasma to the other.

[0038] In one embodiment, two plasma devices are connected in parallel, with high-voltage and low-voltage electrodes arranged alternately, and the middle electrode is shared, saving space and allowing the plasma plumes to be better connected. Similarly, the quartz glass tubes used as reaction electrodes are also arranged with positive and negative electrodes, saving space and allowing the plasma plumes to be connected.

[0039] In one embodiment, the electrode 4 is made of tungsten rod. The high-temperature resistance of tungsten rod electrodes can increase the lifespan of the plasma brush electrode.

[0040] In one embodiment, a rectangular notch is provided at the outlet of each plasma device body to enhance the discharge at the outlet, generate a longer plasma plume, and also promote better convergence of plasma plumes in different channels. This notch was determined through simulation and experimental verification. When the notch length is greater than 2 mm, the plasma brush discharges prematurely before the channel, resulting in a shorter plasma plume. When the notch length is less than 2 mm, the discharge is insufficient, also leading to an excessively short plasma plume. When the width of the rectangular notch is greater than 1.5 mm, the plasma plumes in different channels cannot couple together to form a unified plasma plume. When the width is less than 1.5 mm, the plasma brush manufacturing process cannot meet the requirements. Therefore, the rectangular outlet is designed to be 1.5 mm wide and 2 mm long.

[0041] like Figure 4 As shown, the quartz glass tube 6 at the connection point of the two plasma device units acts as a barrier medium, making the discharge intensity at the outlet higher than inside the cavity, so that the plasma is generated at the outlet as much as possible. 7 is the outlet splicing position. The second quartz glass tube position 8 completely exposes the second electrode and the barrier medium, so that the plasma plumes of adjacent gas channels can be connected into one piece, and at the same time, a longer plasma plume can be blown out, which is conducive to the fusion of plasma plumes formed by different plasma reactors into a whole area during discharge.

[0042] like Figure 5 As shown, taking two plasma brushes connected in parallel as an example, the plasma plume 9 generated by the plasma device in the figure can form a brush-shaped plasma plume 9 with a width of 30 mm and a length of 15 mm under the condition of two reactors connected in parallel.

[0043] In one embodiment, a flow equalization plate 10 is provided inside the plasma, such as... Figure 7 As shown, the flow equalization plate 10 has multiple openings. This flow equalization plate 10 can make the generated plasma plume more uniform, achieving a better surface treatment effect. In the design of this flow equalization plate, each hole has a diameter of 1 mm. In COMSOL flow field simulation, when the hole diameter is greater than 1 mm, the flow field uniformity decreases; when the hole diameter is less than 1 mm, the outlet flow velocity decreases. Therefore, the hole diameter is set to 1 mm. The hole density is as high as possible within the limits of 3D printing technology; here, the spacing between the holes is 0.5 mm.

[0044] In one embodiment, the quartz glass tube 6 is encased in a rubber shell 11. The rubber shell 11 protects the glass tube, which acts as a barrier medium, and also houses embedded wires 12, to which a tungsten rod is connected by welding. The tube is connected to a power source via a power cord plug 13.

[0045] This scalable plasma brush device is essentially a double-block dielectric discharge. It is powered by a conventional microsecond pulse power supply, and the gas flow rate is controlled by a conventional flow meter.

[0046] Dielectric barrier discharge (DBD) is a non-equilibrium gas discharge in which an insulating dielectric is inserted into the discharge space; it is also known as dielectric barrier corona discharge or silent discharge. DBD can operate at high pressures and over a wide frequency range, typically from 10 kPa to 500 kPa, and with power frequencies from 50 Hz to 1 MHz. Because this invention requires merging plasma plumes generated in different reaction chambers into a single region, synchronous discharge from these chambers is essential. Therefore, the spacing between electrodes must be strictly controlled during the design process to ensure consistency. This design utilizes 3D printing technology to reduce errors between electrodes, further enhancing discharge synchronization.

[0047] Furthermore, to accommodate materials of different sizes, the plasma device incorporates an expandable design. Through structural improvements and external mechanical design of the plasma brushes, parallel expansion of the plasma brushes is achieved. The electrodes are arranged in a parallel manner, reducing the lateral length and laying the foundation for parallel expansion of the plasma brushes. This parallel expansion is further facilitated by an external slot design.

[0048] like Figure 6 As shown, the internal gas channel 14 of each plasma device unit is wedge-shaped, with the plasma channel at the inlet being significantly wider than the channel at the outlet. This design allows for a higher gas velocity at the outlet, resulting in a longer plasma plume. It also reduces the requirement for inlet gas velocity, lowering the cost of the plasma brush. The wedge-shaped design inside the plasma brush allows for a higher velocity at the outlet with a lower inlet velocity (saving gas), facilitating the formation of a longer plasma plume. Simultaneously, the gas channel must be of sufficient length to ensure uniform mixing of the internal gas after passing through the flow equalization plate.

[0049] At the same time, the airway must be of sufficient length to ensure that the internal gas can be mixed evenly after passing through the flow equalization plate.

[0050] like Figure 8 As shown, users can adjust the discharge operating conditions via the control panel, mainly including power frequency, voltage, and pulse width to control the discharge intensity. They can also control the airflow to regulate the length of the plasma brush. Drive power parameters and gas parameters are sent to the power and gas sources to generate brush-shaped plasma for treating the surface of the target object.

[0051] The flow velocity distribution diagram inside and at the outlet of airway 14 is shown below. Figure 9 As shown. From Figure 9(a) It can be seen that without the flow equalization plate, the two inlets at the inlet converge rapidly, resulting in a phenomenon where the flow velocity is lower on both sides and higher in the middle. As the airflow moves towards the outlet, the phenomenon of higher velocity in the middle and lower velocity on both sides remains quite obvious. Simultaneously, the two plasma brushes are separated at their outlets, causing the parallel plasma brushes to exhibit an intermittent state in the middle, which is unfavorable for the formation of plasma brush plumes. Figure 9 As shown in (b), after the flow equalization plate is introduced, the airflow becomes more uniform after passing through it. As the gas flows towards the outlet, the flow velocity becomes even more uniform, and there is no obvious separation between the two airflows at the outlet. This has a beneficial effect on the continuous state of the parallel plasma plume.

[0052] like Figure 10 The image shows the parallel emission of two plasma brushes. It can be seen from the image that when the gas flow rate reaches 15 L / min, the two plasma plumes can form a better single piece, thereby producing a larger plasma plume to meet the processing needs of different sizes.

[0053] like Figure 11 The image shows the spectrum of two plasma brushes connected in parallel. By measuring the helium atom intensity at 587.6 nm at different horizontal positions at the plasma brush outlet, it can be found that the expanded plasma brush has a relatively uniform particle distribution.

[0054] Compared to existing plasma processing devices, this device does not require operation within a specific reaction chamber, which can effectively reduce the cost of industrial production.

Claims

1. A portable plasma device for multi-scale surface modification, comprising multiple plasma device units connected in parallel, characterized in that: The plasma device unit has side ears and slots on its left and right sides, respectively, which can fit together perfectly. The plasma device unit has a hollow interior with an air inlet at one end and an air outlet at the other end. Both sides of the plasma device body and the connection point of the plasma device unit have identical quartz glass tubes with one end sealed and longer than the width of the side. Each quartz glass tube contains an electrode, with high-voltage electrodes and low-voltage electrodes alternately arranged from the plasma side to the other. The electrodes are made of tungsten rods.

2. The portable plasma device for multi-scale surface modification as described in claim 1, characterized in that: Each plasma device has a rectangular notch at its outlet, designed to ensure the formation of a continuous plasma plume at the outlet.

3. The portable plasma device for multi-scale surface modification as described in claim 1, characterized in that: Both the first and second quartz glass tubes are encased in rubber shells.

4. The portable plasma device for multi-scale surface modification as described in claim 3, characterized in that: A wire is embedded inside the rubber shell of the first quartz glass tube. The first electrode is connected to the wire and connected to the power supply through a power cord plug.

5. The portable plasma device for multi-scale surface modification as described in claim 4, characterized in that: The power supply is a high-frequency AC power supply or a microsecond power supply.

6. The portable plasma device for multi-scale surface modification as described in claim 1, characterized in that: The air inlet is provided with two air inlets.

7. The portable plasma device for multi-scale surface modification as described in claim 1, characterized in that: Each plasma device unit has a wedge-shaped internal air passage, with the inlet channel being wider than the outlet channel.

8. The portable plasma device for multi-scale surface modification as described in any one of claims 1-7, characterized in that: In a single plasma device unit, the electrode structure is a parallel rod electrode. When multiple plasma device units are connected in parallel, they are parallel rod electrodes with alternating positive-negative-positive electrodes. Quartz glass tubes are exposed at the outlet gaps of two adjacent plasma device units to enhance the local electric field, break down the working gas, and generate plasma.

9. The portable plasma device for multi-scale surface modification as described in any one of claims 1-7, characterized in that: A flow equalization plate is provided inside the cavity, and the flow equalization plate has multiple openings.

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