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Plasma plastic cleaning machine Langmuir oscillation and oscillation frequency

Plasma plastic cleaning machine Langmuir oscillation and oscillation frequency

A strong electric field will be generated when the charge is separated in the plasma due to the thermal motion of particles, but the macro neutral plasma of plasmas cleaning machine has a strong recovery trend. Because of the small mass of electrons in plasma, the motion of electrons is the fundamental cause of the collective motion of plasma. The following is an example of one-dimensional motion.

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Application of low-temperature plasma surface treatment technology on plasma aluminized base film

Application of low-temperature plasma surface treatment technology on plasma aluminized base film

As a new surface treatment technology, low temperature plasma surface treatment technology has unique advantages. Low temperature plasma technology adopts gas reaction, the whole process is liquid free and the reaction is fast. It has the advantages of high efficiency, energy saving and environmental protection. Low temperature plasma technology is widely used in a variety of applications, from the microelectronics industry to the manufacture of integrated circuits, to the treatment of a variety of polymer films, and a wide range of toxic waste treatment applications.   Low temperature plasma treatment technology applied to aluminum-based films: The purpose of the aluminized substrate film pretreatment is to improve the adhesion of the aluminized layer, improve the barrier effect of the aluminized layer (such as blocking gas, light, etc.), and improve the uniformity of the aluminized layer. In the plasma pretreatment process, the surface cleaning and activation of the substrate membrane is chemically modified to make it more firmly bound to aluminum metal atoms.   Mobile film roll of polymer membrane plasma processing, can remove dirt from polymer surface, and can easily open the chemical bonds of the polymer surface, making it a free radicals, and with the free radicals, atoms and ions in the plasma reaction produces new functional groups, such as hydroxyl (hydrogen) (OH), cyano (CN), carbonyl (- C = O), carboxyl (-cooh) group or amino (NH3), etc. These chemical groups are key to enhancing adhesion. Carbonyl groups play a key role in adhesion to the aluminum layer by improving the adhesion between polymer surfaces and other materials deposited on these surfaces. These functional groups improve wettability.   Of course, low-temperature plasma surface treatment technology is an effective way to improve the surface properties and functions of various plastic films. After the film surface can be treated, there will be a great improvement, so it will improve the wettability and binding force of these films. Especially for PTFE film, the treatment effect can not be achieved by other treatment methods. Plasma surface treatment technology is a safe and environmentally friendly way.

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Plasma washer atmospheric pressure pulsed DC discharge plasma

Plasma washer atmospheric pressure pulsed DC discharge plasma

Atmospheric pressure plasma refers to the discharge plasma generated near atmospheric pressure. It does not need to use expensive and cumbersome vacuum system, and its process design is more flexible, showing a broad application prospect in energy gas conversion, material preparation and surface modification, environmental protection and other aspects. In addition, plasma washer atmospheric pressure plasma can discharge directly in the surrounding atmosphere, making it possible to realize plasma medicine.   The common ways of producing atmospheric pressure plasma include DC discharge, dielectric barrier discharge, radio frequency discharge, microwave discharge and pulse discharge. Various forms of atmospheric pressure plasma can be realized through different electrode designs and mode selection. The following is the introduction of plasma cleaner atmospheric pressure pulsed DC discharge plasma.   The pulse voltage parameter of atmospheric pressure pulsed DC discharge plasma has an important influence on the discharge effect. These parameters include the rising edge, falling edge and pulse repetition frequency of the pulse voltage. Compared with traditional AC drive, pulsed DC drive has the advantages of higher electron density, higher average electron energy of plasma and higher energy efficiency.   Atmospheric pressure pulsed DC power supply USES energy storage capacitor, and generates pulse high voltage by rotating spark clearance RSG to discharge load, which has the characteristics of steep rising edge and narrow pulse width, so that energy can be effectively injected into the reactor, and the power supply itself consumes less energy.   The voltage is output by the auto-voltage regulator, which is boosted by the high-voltage transformer and rectified by the full-wave rectifier. Then the energy storage capacitor C1 is charged. When the spark gap RSG1 is switched on, C1 is charged to the pulse capacitor C2 through the current limiting resistor R. At the moment of RSG2 conduction in the rotating spark gap, the energy on C2 is released to the reactor through RSG2, thus obtaining a high voltage pulse in the reactor. Because RSG1 and RSG2 spark-gap are placed on the same rotation axis, they cannot conduct at the same time. This ensures that C1 charging C2 and C2 discharging to the reactor are two independent processes.   By adjusting the output of the auto-voltage regulator, the voltage value on C2 can be changed, thus changing the peak pulse voltage. The pulse width is mainly determined by the volume of C2. The pulse repetition frequency is determined by the rotational speed of the RSG shaft, which can be adjusted by the speed-regulating DC motor. The motor speed regulating part and the pulse high voltage part are electrically isolated by 1:1 isolating transformer. The conversion of positive and negative pulse voltages can be obtained by interchanging the two wires charging C. The low-voltage control part of the power supply (220V) includes voltage regulation and motor speed regulation. The high voltage part and pulse forming part of the plasma cleaner pulse power supply should be placed in the shielding net to prevent electromagnetic radiation from interfering instruments and equipment and harmful to human body. If the mode of cusp discharge is adopted, according to the mode of discharge, the atmospheric pressure pulsed DC discharge can occur between corona discharge and spark discharge.   When the voltage of the charged body at the tip reaches a certain value, local ionization and excitation of the surrounding gas media occur to form a discharge channel. The discharge process is accompanied by a weak glow and sound, and corona discharge occurs when no breakdown or conduction of the electrode occurs. When a breakdown or conduction occurs between the plasma washer electrodes, a spark discharge occurs, accompanied by a strong light and sound. Wang Kangjun studied the effect of pulsed spark discharge and pulsed corona discharge on methane conversion under atmospheric pressure. The results show that the conversion rate of methane and the selectivity of C2 hydrocarbon (mainly including ethane, ethylene and acetylene) in spark discharge are superior to that in corona discharge, and the main C2 hydrocarbon product in spark discharge is acetylene, while the main C2 hydrocarbon product in corona discharge is ethane.

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Plasma surface modification equipment for medical devices

Plasma surface modification equipment for medical devices

Another important application of plasma surface modification equipment is to promote cell growth or protein binding, thereby reducing thrombus formation. The polytetrafluoroethylene coating and organosilicone monomer have blood compatibility. The fluorocarbon ratio (F/C ratio) and the presence form of wettability in the film are obviously closely related to the absorption and storage of fibrinogen, a protein in the blood that participates in the coagulation process of blood. PECVD can be used to prepare polytetrafluoroethylene films with different surface morphology.   Silane - like films can be obtained by plasma polymerization of organosilicon monomer. The SiCHO compound was applied to the blood filter and the hollow fiber membrane of polypropylene to coat the activated carbon particles. Hemoperfusion device is to circulate the blood of the patient's artery into the hemoperfusion device, so that the poisons and metabolites in the blood are adsorbed and purified, and then injected back into the body. The absorbent of hemoperfusion apparatus mainly includes activated carbon, enzyme, antigen and antibody, etc. The carbon particles must be coated with a polymer film to prevent fine particles from entering the blood. Similarly, the microporous polypropylene blood oxygenator needs to be coated with a silane polymer film to reduce the roughness of the polypropylene surface and thus reduce damage to blood cells.   Heparin and heparin-like molecules, collagen, albumin, and other life-giving molecules can be fixed on the surface of the polymer and act as antithrombotic agents. So to fix these molecules to the surface of the polymer, you need to activate the polymer and respond to the grafted molecules. This process mainly adopts the experimental and empirical method, and the graft base groups used are mostly NH3, OH and -COOH, which are mainly obtained from raw materials supplied by non-precipitation. Amino functional groups appear on the surface of materials treated by ammonia gas plasma, which are similar to liver phosphorus ester and can be used as attachment points of anticoagulants. Examples of this kind of plasma used in vitro medical utensils include cleaning and modification of petri dishes for experiment or drug production, and surface modification of microporous plates. The surface modification can also improve the biocompatibility of human implants. For example, the biocompatibility of artificial blood vessels, contact lenses and drug delivery implants could be improved by improving the adhesion of blood-capacity coatings to materials. In some applications, such as contact lenses and intraocular lens materials, surface treatments can also reduce protein or cell adhesion.   Many materials encourage proteins to bind, leading to the formation of blood clots. Anticoagulant coating can effectively reduce surface clotting and thrombosis, but antithrombotic materials often cannot be well combined with polymer surface. The active free radicals in plasma were used to enhance the effective chemical bond on the surface of the material through heparinization or grafting of antithrombolytic groups. The effect of material surface modification depends on a number of factors, including the choice of material matrix, composition of antithrombotic coating, and service life of the modified material. Animal experiments showed that the plasma-activated modified polyurethane catheter showed no protein attachment after 30 days of use. The plasma-activated polyurethane catheter without heparin coating showed a small amount of protein attachment. There was serious thrombus in the fluid guide tube without plasma surface modification. Compared to the untreated blood filter, the improved blood filter can significantly reduce the amount of platelet adhesion.

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Atmospheric pressure plasma cleaning ritualistic reaction process diagnosis technology

Atmospheric pressure plasma cleaning ritualistic reaction process diagnosis technology

Atmospheric pressure plasma is an important technology for energy gas conversion, material preparation and surface modification, environmental protection and biomedicine. There are many process variables in plasma, such as plasma temperature, density, various active species, etc., which affect the interaction between plasma and reaction medium and determine the structure and properties of reaction products or materials. The plasma temperature, density and various active species depend on the macroscopic parameters and conditions of the plasma, such as pressure, power and gas flow rate. Therefore, the diagnosis of plasma process is helpful to obtain the micro-mechanism of plasma discharge, establish the correlation between plasma process parameters and the results of plasma reaction, and find the internal information between them, so as to realize the controllability of plasma process.   Cleaning instrument plasma diagnosis technology is divided into off-position technology and in-situ technology. The offsets technique involves the extraction of plasma samples from a plasma reactor, such as mass spectrometry and gas phase electron paramagnetic resonance. The in-situ technology of atmospheric pressure plasma cleaning instrument includes invasive and non-invasive diagnostic techniques: invasive diagnostic techniques disturb the plasma, such as probe technique; The perturbation of plasma by non-invasive diagnostic techniques, such as spectroscopic diagnostic techniques, can be ignored. In atmospheric pressure plasma, spectral diagnosis is a common diagnostic technique.   Spectroscopic diagnosis technology is an important means to diagnose the complex physical and chemical processes occurring in the plasma and to measure the plasma temperature. It has the advantages of simple operation, good selectivity, high sensitivity and accuracy and no interference to the plasma. Spectroscopic diagnostic techniques mainly include emission spectrometry, absorption spectrometry and laser induced fluorescence.   OES is a common method to monitor and diagnose plasma processes. The spectral features of the emission spectrum provide rich information about the chemical and physical processes in the plasma. By measuring the wavelength and intensity of the spectral lines, various ions and neutral groups in the plasma can be identified.   The emission spectrum of atmospheric pressure plasma cleaning instrument can be divided into linear spectrum, banded spectrum and continuous spectrum, which are mainly used in the diagnosis of plasma emission spectrum. The atomic spectrum is generally linear, for example, the spectrum of hydrogen atom is simple atomic spectrum, it has mutually independent spectrum, only one line in the visible region, namely the Balmer line, the brighter four lines are: Hα-656.28 nm，Hβ-486.13 nm，Hγ-434.05 nm， Hδ-410.18 nm.

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Emission spectrum diagnosis of the reaction process temperature of the plasma cleaning system

Emission spectrum diagnosis of the reaction process temperature of the plasma cleaning system

Emission spectrum diagnosis of the reaction process: There are many chemical reactions in atmospheric plasma of plasma cleaning system. These chemical reactions can be used to synthesize high value-added chemical raw materials, modify the surface of materials and degrade environmental pollutants. Chemical reactions vary, but they are essentially recombinations of atoms or groups of atoms into products. The electrons, ions, excited atoms, molecules and free radicals in plasma are very active reaction species, which can change the chemical reaction path effectively in the process of chemical reaction. Spectroscopic diagnosis can directly obtain the type and intensity of the active species in the plasma and provide experimental basis for revealing the chemical reaction mechanism.   The main product of CH4 in atmospheric pressure DC discharge plasma is C2H2. CH3, CH, H, C2 and C active species can be found in the CH4 plasma from the emission spectrometric diagram of CH in the atmospheric pressure DC discharge plasma. According to the spectral detection results, C-H fracture of CH4 directly occurs in the plasma, and CH active species is the main reaction intermediate species.   Emission spectrum diagnosis of system temperature:   In atmospheric plasma, the electron temperature of plasma is difficult to be measured due to the interference of probe and other diagnostic techniques. However, the temperature of plasma system at atmospheric pressure can be achieved by studying the rotational temperature of gas molecules. It is a convenient and feasible method to collect the plasma gas temperature data by emission spectrum, which will not affect the discharge process and can obtain the discharge temperature accurately. High gas density in the atmospheric pressure plasma, frequent collision of gas molecules and ions, not only makes the ion balance the number of particles on the rotational level, and translational temperature reach equilibrium with the gas molecules and the rotation of the molecules can reach thermal equilibrium and the translational energy of the particles of relaxation time is very short, it is generally believed rotational temperature and gas temperature in the process of discharging is close to equal, therefore plasma cleaning system can be calculated by measuring the high rotation spectrum of rotational temperature, so as to estimate the gas temperature of plasma.   Spcair is a software that calculates the isomeric spectrum based on the particle number distribution on the energy level satisfying boltzmann distribution. Since its characteristic parameters include each characteristic temperature of the plasma, the plasma temperature at atmospheric pressure can be easily obtained by comparing the actual measured spectrum and the calculated spectrum of the plasma.   To determine plasma temperatures, the oscillatory and rotational temperatures of chlorine molecules were determined by spectrometric measurements of the second positive N2(C3π) emission spectra compared with those simulated using Speair. The second positive band N2(C3π) emission spectra of nitrogen molecules and the second positive band emission spectra of ammonia molecules were obtained by dielectric barrier discharge at atmospheric pressure at discharge voltage 25.4kV, discharge frequency 13.8kHz and flow rate of N2 at 100ml/min. It can be seen from the result diagram that the fitting spectrum is very consistent with the experimental spectrum. Specair can directly obtain that the rotation temperature of the gas under the above experimental conditions is 520K, and the plasma temperature is also 520K. When the discharge voltage is 30kV and 33kV respectively at the same discharge frequency, the plasma temperature is 580K and 600K.

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