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Discussion on Plasma Relaxation and Transport in Plasma Surface Treatment Factory

Discussion on Plasma Relaxation and Transport in Plasma Surface Treatment Factory

The transition process of non-thermal equilibrium plasma to equilibrium state can be divided into relaxation process and transport process. The former describes a transition from a non-thermal equilibrium velocity distribution to a thermal equilibrium Maxwell distribution, and the latter describes a stable non-thermal equilibrium state, that is, matter, momentum and energy flowing in space, etc. The relaxation process is usually described in terms of different relaxation times, and the basic principle is the collision between charged particles. The interaction between charged particles is the long-duration Coulomb force, a particle can interact with multiple particles in the long range of Debai simultaneously, and they can produce near collisions (two particles collide close together) and far collisions (one particle collides with many particles at a long distance). The collision of charged particles in plasma has a characteristic that the effect of far collision is much greater than that of near collision. The time of conflict and the mean free path L are mainly dependent on the distant conflict. For high temperature plasma, there are three important relaxation times: longitudinal deceleration time, transverse deflection time, and energy homogenization time T ^. The relaxation time of electrons is different from that of ions. In a plasma that is not thermal equilibrium at the beginning, electrons will first reach thermal equilibrium after collision, and then they will reach thermal equilibrium between electrons and ions. Electrical conductivity, permeability, viscosity and thermal conductivity are important parameters in plasma transport. One of the features is bipolar diffusion. For example, electron diffusion, electrostatic energy between electrons and ions makes ions diffuse together, resulting in slower electron diffusion and faster ion diffusion, both of which diffuse at the same rate, namely the so-called bipolar diffusion. In addition, the plasma is in a magnetic field, and the transport along the magnetic field is basically unaffected by the magnetic field, while the transport across the magnetic field is blocked by the magnetic field. Due to the drift caused by the magnetic field gradient, the orbit of the confined particles will change in the high-temperature rarefied plasma in the annular magnetic field, thus increasing the free migration path and greatly improving the transport coefficient. Based on the analysis of this magnetic field configuration, a transport theory, called the Neoclassical theory, is derived, which is still a collision theory. This theory is of great significance for the study of controlled thermonuclear fusion, and it can explain to some extent the large ionic thermal conductivity observed in the ring device. In experiments by Tokamak et al. it was found that some transfer coefficients, such as electron thermal conductivity, were much larger than the results of the neoclassical theory. For some experiments and inertial confinement fusion, we find that the transfer coefficients are much smaller than those obtained by classical theory. Transport phenomena which cannot be explained by any collision theory are called anomalous transport. At present, it is generally believed that anomalous transport is caused by nonlinear process turbulence. The problem of anomalous transport is related to whether the particles and energy of plasma can be effectively controlled, which has become an important subject in current fusion theory research. The above is the CRF plasma surface treatment manufacturers to discuss the plasma relaxation and transport problems, I hope to help you.

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Plasma generator manufacturer DC discharge to produce plasma theory

Plasma generator manufacturer DC discharge to produce plasma theory

There are two kinds of plasma gas discharge, one is DC and the other is AC. DC discharge usually refers to low-frequency discharge. Under different pressure and current range, due to the number of electrons in gas, collision frequency, particle diffusion and heat transfer velocity are different, there will be dark current area, glow discharge area and arc discharge area. The magnitude of the current depends on the power supply load characteristic curve corresponding to the falling line of resistance R1, R2 and the discharge characteristic curve intersection (operating points A, B, C). 1. Dark current area: The electromagnetic field accelerates the electrons, so that they gain enough energy, through the collision with neutral molecules, the number of new electrons rapidly increased, when the current reaches 10-7~10-5 A, there will be a very thin layer of light near the anode. 2. Glow discharge area: When the current is increased again (10-5~10-1 ampere), the cathode will be bombarded by ions at low pressure and accelerate toward the anode direction, thus giving off electrons. Near the cathode, there is a cathode drop region with a large potential difference. In the middle part between the electrodes, there is a positive column region with a small potential gradient, and the medium is non-equilibrium plasma. When there is no gas convection, electrons and ions in the positive column diffuse towards the wall at the same speed, and combine on the wall, releasing energy. In classical theory, the distribution of electron density on the cross section is in the form of Bessel function. There is an anode potential drop region several millimeters thick near the anode, and its potential difference is basically equal to the gas ionization potential difference. 3. Arc discharge area: When the current exceeds 10-1 A and the pressure is also high, the Joule heat generated in the positive column area is greater than the heat dissipation of the particle diffusion zone to the wall, so that the temperature in the center of the positive column area increases, the gas conductivity increases, so that the current concentrates in the center of the positive column area, forming unstable contraction. The conducting positive column will shrink into an arc with higher temperature and higher current density, that is, arc discharge. The current density is 104~106 A/cm, forming "cathode spot" on the cathode, according to the mechanism of hot electron emission (hot cathode) or field emission (cold cathode), electrons are emitted. There are also "anode spots" on the cathode. Because the electrons carry their kinetic energy into the anode, they release energy equivalent to the work that was lost when they enter the anode. Combined with the heat in the falling region of the anode, the anode heats up much more than the cathode. The above is the CRF plasma generator manufacturers to DC discharge to produce plasma theory discussion, I hope to help you.

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Plasma cleaning technology to improve the manufacturing process performance of composites

Plasma cleaning technology to improve the manufacturing process performance of composites

The liquid molding technology of composite materials mainly includes resin transfer mold (RTM), vacuum assisted resin transfer mold (VARTM), vacuum assisted resin injection mold (VARI) and resin film penetration mold (RFI). The common characteristic of this process is that the fiber preformed body is put into the mold cavity, and then the liquid resin is injected under the action of pressure, so that it is fully impregnated with the fiber, and then through curing, demoulding and other processes, the required products are produced with less investment, high efficiency and good quality. However, the problem to be solved is that in LCM process, there are a large number of resins that are not ideal for fiber impregnation, and there are holes in the product and dry spots on the surface. It is indicated that the wetting property of resin on fiber surface will directly affect the molding process and product properties of LCM. May be considered by plasma cleaning technology to improve the physical and chemical properties of fiber surface, improve the preforming of the fiber surface free energy in the body, make the resin in the same process conditions (pressure field, temperature field, etc.) can more fully impregnated fiber surface, improve the dipping uniformity, improves performance of the composite material liquid molding process.

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Plasma technology to improve the bonding properties of multiple components of composite materials

Plasma technology to improve the bonding properties of multiple components of composite materials

In certain applications, it is necessary to connect multiple composite parts into a whole through adhesive bonding process. In this process, it is difficult to complete the bonding process between composite parts by adhesive coating, because the surface of the composite material has dirt, is smooth or is chemically inert. Using the method of physical grinding, the surface roughness of the composite parts is increased, so as to improve the bonding performance between the composite parts. However, this method is difficult to achieve the purpose of uniformly increasing the surface roughness of the parts while producing dust pollution to the environment, which is easy to cause the deformation and damage of the surface of the composite parts, and then affect the performance of the adhesive interface of the parts. Therefore, the simple and easily controlled plasma technology can be considered to effectively clean the surface contaminants of composite material products, and improve the surface physical and chemical properties, so as to achieve a good bonding effect. Application of plasma cleaning technology to clean composite material, whether it is used to improve the interface of the composite performance, improve the wettability on the surface of the liquid molding process of the fibers in the resin to, or used to clean up the dirt layer on the surface of the parts, to improve the coating performance, or to improve the bonding performance between multiple parts, its reliability mainly depends on the low temperature plasma on the improvement of material surface physical and chemical properties, or used to remove the weak interface layer, or used to increase the roughness, improve the chemical activity, thus improve the infiltration and bonding performance between the two surfaces. With the growing maturity of low-temperature plasma technology and the development of cleaning equipment, especially atmospheric on-line continuous plasma equipment, the cleaning cost is constantly reduced and the cleaning efficiency is further improved. Plasma cleaning technology itself has the advantages of convenient processing of various materials, green and environmental protection. With the gradual improvement of people's understanding of fine production, the application of advanced cleaning technology in the field of composite materials will be widely promoted.

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How is the vacuum plasma processor to remove the rust spots on the bronze ware

How is the vacuum plasma processor to remove the rust spots on the bronze ware

As we all know, bronze excavated for a long time buried underground, bronze and the surrounding environment reaction to form copper rust, can be divided into two types of harmless rust and harmful rust. Hinnocuous copper rust is also one of the reasons why people like bronze ware. It is the natural protective layer (i.e. coating) of bronze ware, which can not only protect bronze ware from corrosion, but also increase the beauty of bronze ware and make it more valuable for collection. And harmful copper rust is green powder, its harm is very serious, and will continue to spread, causing damage to bronzes. So, does the vacuum plasma cleaning machine help bronze rust removal? Today we will show you how the vacuum plasma processor is to remove the rust on the copper plate, for your reference. For those who prefer small collections, harmful rust in bronze vessels can be removed in time, and there are many options, such as physical grinding, rust remover cleaning, etc. However, if it is used improperly and operated correctly, it is easy to cause damage to the device. China will excavate a large number of bronzes every year, you can see are often some representative, well-preserved artifacts, which are also a lot of collected bronzes, these artifacts are also to do a good job of anti-rust treatment, otherwise it will cause batch loss. The vacuum plasma processor can remove copper rust without damaging the copper surface, and can also remove harmless copper rust. In order to protect harmless corrosion, auxiliary protection measures should be added, so it is more suitable for the application of overall removal of copper rust, such as the study of ancient bronze inscriptions and ornamentation.

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The potential application of germanium in integrated circuits and its etching method (I)

The potential application of germanium in integrated circuits and its etching method (I)

Using germanium instead of silicon seems like an ironic twist. The transistor invented at Bell Labs in 1947 was made from plates of germanium, the element below silicon in the periodic table. Germanium was chosen because current flows through it quickly, a characteristic of transistors. But when engineers considered making integrated circuits on a large scale, germanium was ignored because silicon was easier to handle. Now, as manufacturers face the problem of silicon not being able to be miniaturized any further, germanium is being used again. The germanium circuits demonstrated by Professor Peide Ye of Purdue University and his colleagues suggest that germanium materials will be commercialized in the coming years. The tiny transistors currently made are just 14nm in diameter and are extremely tightly packed together. Further reduction in the size of transistors would pose a serious challenge to the semiconductor industry. During a panel session at the Electronics Devices Conference 2016, Intel researcher Mark Bohr said that it will be impossible to shrink silicon transistors any further in 10 years. "I'm usually more interested in new ideas," says Bohr. Germanium has good electrical properties, so the circuit speed is always better than silicon. However, engineers cannot use germanium to make compact but energy-efficient circuits based on the current production technology used in the industry, called complementary metal oxide semiconductor (CMOS) or complementary gold oxide semiconductor. The circuit made of complementary AO semiconductor adopts the transistor which transmits negative charge at the same time, namely the negative electric field effect transistor. Transistors that transmit positive charges, known as positive field effect transistors, "but germanium transistor technology with negative field effect is hitting a bottleneck". Ye Peide proposed a new design of germanium transistor with negative electric field effect to improve its performance significantly. Saraswat was instrumental in bringing germanium back into the spotlight. In 2002, he published a paper showing that germanium transistors were two to three times as high as silicon transistors. "We have done the basic science work and now we are focusing on the basic engineering," Saraswat said. Other materials available, such as carbon nanotubes or multielement composite semiconductors, are promising to replace silicon, but they are used in more complex ways that make them difficult to use in the chip industry. Chip makers, by contrast, have used germanium for positive field effect silicon transistors.

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