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Discussion on plasma instability of plasma cleaning machine manufacturers

Discussion on plasma instability of plasma cleaning machine manufacturers

Plasma instability can be roughly divided into macroscopic instability and microscopic instability. Where the instability region develops on the micro scale, such as the cyclotron radius and Debye length of the particle, is collectively referred to as the macro instability. An instability that develops only on a microscopic scale is called a microscopic instability. Macroscopic instability can cause a wide range of plasma disturbances, which can seriously damage the equilibrium. The main reason is that the excess energy bound to the magnetic field is stored in the plasma. In addition, the diamagnetism and other characteristics of the plasma also lead to macroscopic instability. This is a very important problem for confined plasmas in controlled thermonuclear fusion devices. There are many types of macro instability. In addition to the distortion instability, the exchange instability is more important, that is, the position of the plasma and the constrained magnetic lift exchange; Ripping modes, where the plasma is torn apart by a magnetic field into tiny beams, and so on. Magnetic fluid dynamics is a commonly used method to study macroscopic instability. In this case, the energy principle is a very effective method, which is to judge whether the equilibrium is stable or not according to the change of the system potential energy caused by the small displacement when the system deviates from the equilibrium. This method is especially suitable for magnetic fields with complex geometry. In addition to the energy principle, the normal mode method is a commonly used analytical method. The method assumes that the perturbation quantity is dq(r,t)=dq(r)-e-iwt. W is usually found as a complex number: W = WR + Iwi. If Wi BBB 0 0, the amplitude of disturbance increases with t, that is, it is unstable; on the contrary, Wi <0, the system is stable. There are many reasons for micro-instabilities. Spatial inhomogeneity, such as density, temperature, magnetic field gradient, etc., which can cause drift and potentially cause instability. Another reason is the inhomogeneity of velocity space, such as anisotropy of velocity, temperature, pressure, etc. In addition, wave to wave interaction and so on can also lead to micro instability. In summary, plasma deviating from thermal equilibrium has excess free energy that must be released to bring it toward equilibrium. The free energy released may cause microscopic instability. Plasmas with micro instability are characterized by increasing fluctuation. This situation often leads to turbulence and anomalous transport. There are many types of micro-instabilities. The main reasons are: secondary instability, which is caused by two beams of particles flowing relative to each other; Drift instability is caused by drift motion caused by various gradients. Loss cone instability caused by anisotropy of velocity distribution, and parametric instability caused by wave-wave interaction, etc. The theory of micro-instability is based on dynamical theory, that is, it starts from the study of Vlasov equation. For the study of instability, linear theory is generally adopted, which can only judge whether the system is stable or not, and sometimes can give the growth rate of instability at the initial moment of the system. The nonlinear theory is needed to study the evolution problem of the perturbation tending to saturation when the amplitude of the perturbation increases under appropriate conditions.

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Research Status of Plasma Radiation of Vacuum Plasma Spraying Factory

Research Status of Plasma Radiation of Vacuum Plasma Spraying Factory

The significance of studying plasma radiation lies in: on the one hand, it is an important way of energy dissipation of plasma; on the other hand, the study of plasma radiation is the necessary basis for in-depth understanding of plasma motion law by means of spectrum analysis and other methods. This is particularly important in astrophysics and space physics because the understanding of distant plasmas has been gained almost entirely through the study of radiation. The radiation of plasma includes: bremsstrahlung, cyclotron radiation, blackbody radiation, Cherenkov radiation, and linear radiation in the transition of atoms, molecules or ions. Bremsstrahlung is the collision between free electron and ion, i.e. the continuous radiation produced by electrons when the ion velocity changes in the Coulomb field. Electron-electron collisions do not change the total momentum of the electrons and therefore do not generate bremsstrahlung. Bremsstrahlung in plasma is mainly caused by distant collisions, and its wavelength generally ranges from ultraviolet to X-ray. Radiation loss is a very important problem for high temperature plasmas. Echo radiation, also known as cyclotron radiation, is the radiation produced by charged particles, mainly electrons, as they move in circles around magnetic field lines. The radiation of non-relativistic electrons is called cyclotron radiation, which is a monochromatic radiation that appears in the form of spectral lines at the electron cyclotron frequency. When the electron energy is high, in addition to the fundamental frequency, it also emits radiation in a harmonic frequency. This type of radiation is nearly isotropic and weak in energy. In the plasma, due to collision and other reasons, the spectral line becomes wider, and the frequency of the spectral line moves to the high frequency direction with the increase of the plasma density. The cyclotron radiation of relative electrons is called synchrotron radiation, which has high power, weak directivity, concentrated in a small area, and is a kind of continuous spectrum. The above is the CRF vacuum plasma spraying manufacturer to explain the plasma radiation research status, I hope to help you.

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Analysis of factors affecting cleaning efficiency of atmospheric pressure plasma cleaning machine process parameters

Analysis of factors affecting cleaning efficiency of atmospheric pressure plasma cleaning machine process parameters

Low pressure plasma cleaning machine is a typical plasma cleaning equipment. Because the production of plasma needs to be carried out under the condition of low pressure, vacuum equipment and closed system are needed, the cost of equipment is high, the operating space and the size of items to be cleaned are easily limited, which is not conducive to large-scale industrial production. So in recent years, the development of atmospheric plasma and its cleaning technology has attracted much attention. Atmospheric pressure jet plasma spray gun is a capacitance-coupled RF discharge device. Its plasma characteristics are similar to glow discharge. When cleaning the material surface, the working gas can be selected according to the characteristics of the pollutants to be cleaned. In addition, there is a atmospheric air dielectric barrier discharge plasma cleaning device, which can be used to clean the surface of continuous fibers, fabrics and other large fabrics under atmospheric pressure. Dielectric barrier discharge (DBD) can produce macroscopic uniform and stable plasma with high discharge intensity and high processing efficiency. During the cleaning process of atmospheric pressure plasma cleaning machine, the main factors affecting the cleaning efficiency of equipment parameters are as follows: (1) Discharge pressure: in the case of low-voltage plasma, discharge pressure increases, plasma density increases, and electron temperature decreases; The cleaning effect of plasma depends on the density of plasma and the temperature of electrons. The higher the density of plasma, the faster the cleaning speed will be. The higher the temperature of electrons, the better the cleaning effect will be. The discharge pressure selection is the key in the process of low-voltage plasma cleaning. (2) Gas types: there are a variety of pollutants on the substrate and surface of the items to be treated, while the plasma cleaning speed and cleaning effect generated by different gas discharges are widely different. Therefore, working gas plasma should be selected specifically. For example, oxygen plasma can be used to remove oil stains on the surface of objects, and mixed gases such as hydrogen and argon can be used to remove the oxide layer. (3) Discharge power: the greater the discharge power, the greater the density of plasma, the greater the energy of active particles, and the better the cleaning effect. For example, the discharge power has a large effect on the density of oxygen plasma. (4) Contact time: the contact time of the material to be cleaned in the plasma has an important influence on the cleaning effect of the plasma and the working efficiency of the plasma. Long contact time, the cleaning effect is better, but the work efficiency is reduced. Also, too long cleaning time can cause damage to the material surface. (5) transmission speed: for atmospheric plasma cleaning process, continuous transmission will be involved when dealing with large objects. The results show that the slower the relative moving speed of the cleaned object and electrode is, the better the treatment effect is. However, too slow a speed on the one hand affects the work efficiency, on the other hand, it will cause damage to the material surface, and the treatment time is too long. (6) Others: parameters such as gas distribution, gas flow rate and electrode setting in the cleaning process of atmospheric pressure plasma cleaning machine will also have an impact on the cleaning effect. Therefore, specific process parameters should be set according to the actual situation and cleaning requirements.

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Plasma surface treatment technology to improve the surface coating performance of composite materials

Plasma surface treatment technology to improve the surface coating performance of composite materials

In the molding process, need to use release agent, to ensure that it can be effectively separated from the mold after curing molding, but the use of release agent will inevitably make the patch surface residual too much release agent, resulting in pollution, weak interface layer, so that the coating is easy to fall off. The conventional cleaning method is to wipe with acetone and other organic solvents or remove the residual release agent after grinding. These release agents remain on the surface of composite material products. However, these two methods not only introduce the use of organic solvents, but also produce a lot of dust pollution in the grinding process, which has a serious impact on the environment and also endangers the personal safety of the operator. By plasma surface treatment technology of green cleaning, the composite coating has reached the better conditions for the coating, coating to improve reliability, effectively avoid the defects such as peeling coating, problems, coating surface smooth, continuous, no flow mark, porosity and other defects, compared with the conventional cleaning, coating adhesion obviously improved after plasma surface treatment, through the GB/T9286 test results of grade 1, satisfies the requirement of engineering application.

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What are the collisions between particles in the plasma cleaning machine

What are the collisions between particles in the plasma cleaning machine

The plasma produced by the plasma cleaner contains a variety of different particles, whose motion rules determine the properties of the plasma environment. Today we will discuss the types of particle collisions. The collision between particles in plasma can be roughly divided into two kinds: elastic collision and inelastic collision. 1. Elastic collision. In the process of plasma collision, the momentum and total kinetic energy of particles are conserved, and the internal energy of the particles involved in the collision remains unchanged. No new particles or photons are generated, but the velocity of the particles will be changed, and the conversion of momentum and kinetic energy will take place. This kind of collision is called elastic collision. 2. Inelastic collision. In the collision process of plasma, the total momentum of particles is conserved, the total kinetic energy is not conserved, and the internal energy of at least one particle changes, such as the companion of new particles and the companion of photons. This kind of collision is called inelastic collision. Because the internal energy of the plasma particle in the plasma cleaning machine changes, the state of the particle will also change, sometimes accompanied by radiation, and even produce new particles, such as the excitation, ionization and fusion process in the plasma. The following table lists the types of inelastic collisions. In the inelastic collision between electrons and atoms, the kinetic energy of electrons can be converted into the internal energy of atoms with high efficiency, and the energy can be completely converted when the energy is high. In an inelastic collision between an ion and an atom, the electron's kinetic energy is low, and at high levels it is only half of its energy. Therefore, as long as the energy of the electron in the plasma cleaning machine is greater than the excitation energy and ionization energy of the atom, the atom is likely to be excited or ionized, and the ion must have twice the excitation energy or ionization energy of the atom, it can be excited or ionized. In fact, when the energy of the ion in the plasma cleaner is several times that of the ionization energy, the probability of inelastic collision is still very small. Only when the ion speed is the same as the electron speed, the probability of inelastic collision can be compared with that of the electron.

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Plasma and material interaction of rotary bottle plasma cleaning equipment

Plasma and material interaction of rotary bottle plasma cleaning equipment

Rotating bottle plasma cleaning equipment often uses different process gases in practical applications. The generated plasma contains a large number of active particles and high-energy particles. The interaction between these particles and the surface of solid materials is of great significance to the plasma itself or solid materials. The particles in the rotary bottle plasma cleaning equipment transfer energy to the surface of the solid material, while the plasma carries away large amounts of impurities. For solid materials, due to the bombardment and energy transfer of these high-energy particles, a variety of physical and chemical reactions take place on the surface of solid materials. Therefore, the study of the interaction process between plasma and the surface of solid materials is very beneficial to the exploration of material surface modification, new materials and new technologies. Bottles of plasma cleaning equipment and all kinds of solid materials on the surface of the effect depends on the physical parameters of plasma, the kinds of solid materials, surface structure and morphology of factors, but plasma and effect on the surface of the solid material in the surface layer of only a few to dozens of nanometer (nm depth), so as not to damage the intrinsic characteristics of matrix; It can also make the material surface have new practicality. Adsorption and desorption of plasma are very important, and in many cases one or the other often determines the mass of the surface. Adsorption results from the attraction between the incident body and the surface. There are two kinds of adsorption: physical adsorption produced in the weak interaction between molecules and the surface, physical adsorption is exothermic, physical adsorption and surface binding energy is very weak, can quickly spread from the surface after adsorption; When the adsorption atoms or molecules and surface atoms form chemical bonds, that is, the formation of chemical adsorption, this process is called the strong exothermic process.

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