Commonly used pressure regulating methods in vacuum application equipment Zhou Zhiwen, Xue Hua (College of Physics and Engineering Technology, Northwest University for Nationalities, Lanzhou Gansu 730030, China) 1 General The application of vacuum equipment is quite extensive, such as vacuum coating, vacuum annealing and vacuum welding. In most vacuum applications, there is a heating source or sputtering source. In order to control the temperature during the heating process or the deposition rate of the sputtering material, it is necessary to control the input voltage of the heating source or the sputtering source in the process. The highest performance-cost ratio for achieving this goal is an important guarantee for the proper use and possession of the vacuum application equipment. Therefore, the selection of a suitable pressure regulation method is the key to the design of vacuum application equipment. The following is a brief discussion of the voltage regulation methods commonly used in various vacuum applications.
2 commonly used pressure regulator method 11, 2 2.1 ordinary regulator pressure regulator This is a widely used and effective pressure regulator. Since the appearance of the self-regulator, it has been occupying an important position in the pressure regulator with a simple structure, reliable use, and a very low failure rate. At present, there are still a large number of applications in the pressure regulating field. There are two commonly used control methods for the voltage regulator: 1 The output voltage is adjusted by shaking the handwheel; 2 The output voltage is adjusted by controlling the rotation of the motor, and closed-loop control can be achieved at this time. The vacuum mirroring machine is the simplest type of vacuum application equipment. It is an aluminum wire heated to an evaporation state in a vacuum state so that it is deposited on the glass to form an aluminum film and the glass is made into a mirror. Due to its simple structure and no additional technical content, its competition in the market is a price competition. The application of a simple and reliable voltage regulation method is the basic requirement of the aircraft. Therefore, the pressure regulation method of the aircraft is basically all using the pressure regulator pressure regulation method. As shown, the evaporation process of the aluminum wire mounted on the tungsten wire is controlled by adjusting the voltage applied to the tungsten wire by the voltage regulator.
1. Voltage regulator 2. Transformer mirroring machine regulator principle. 2 Magnetic regulator Voltage regulator Magnetic regulator, also known as controllable transformer, is a kind of non-mechanical transmission, non-contact voltage regulator, one of its distinguishing features is that it can carry out smooth stepless voltage regulation with load.
The regulation of the voltage is to use small direct current to control the change of AC power of higher power. That is, when the control current increases from small to large, a small voltage increases from the load.
The temperature in the vacuum furnace is generally required to be controlled within an accurate range. In addition, since the device to be processed is expensive, the electronic control also has higher requirements. The magnetic regulator has the same low failure rate as the common regulator. For the above reasons, the heating power supply in the vacuum furnace is generally selected by the magnetic regulator pressure regulator. When the temperature closed-loop control is used, the commonly used control methods are as shown. The temperature control in the vacuum furnace can be achieved through the illustrated control circuit, and its accuracy is generally up to ± rc. 1. Temperature Control Table 2. Silicon-Controlled Rectifier 3. Magnetic Regulator 4. Load 5. Thermocouple Magnetic Regulator The vacuum furnace temperature control circuit composed of the device is composed of a saturable reactor in the magnetic voltage regulator, and the reactance winding has a current limiting function, so that a better falling external characteristic can be obtained. When the DC control current and input voltage are rated, the short circuit current generated between the output terminals is 1.5 times the rated current. It can be seen that the magnetic pressure regulating instrument has a finite flow effect and does not burn transformers or other components due to overcurrent, and it is particularly strong to withstand load short circuits.
Magnetic regulators are not suitable for no-load regulation. When the load resistance is greater than the rated value, the lower limit of the regulator will increase. The V/I relationship between the magnetron targets in the magnetron coating machine is as shown. Before the gas discharge, a higher voltage is required. At this time, the load resistance is also large. When the normal discharge state is entered, the resistance will be Decrease, which is consistent with the characteristics of the regulator.
Due to the above reasons, in the magnetron sputtering coating machine, the magnetic control power supply can also select the magnetic pressure regulator to adjust the pressure. The common control methods at this time are as shown. The program has been used in a company's coiled magnetron coating machine and is reliable in operation. In this process, attention should be paid to the calculation of the magnetic regulator parameters. If the magnetic regulator is not selected properly, the lower limit output value will be too high to affect the start-up.
The volt-ampere characteristics of gas discharge (turning to page 18) usually the cost of land-based wind farms is about 70% to 80% of wind turbines, and infrastructure (basic grid, roads, etc.) is about 20% to 30%, and at sea The cost of wind farms is about 30% of wind turbines, and about 70% of infrastructure (basic submarine cables, etc.). However, due to good wind resources, offshore wind farms can generate 50% more power per year than onshore wind farms. Due to the adoption of the above new technologies, offshore wind turbines have reduced their cost, increased operational reliability and reduced operating costs, which can result in power generation costs equal to or lower than onshore wind farms.
4 Conclusions China has abundant wind energy resources, with 250 million kW of wind energy resources available for development on the land, and more than three times as much wind energy as offshore. As of the end of 2003, there were 40 wind farms in operation in China (excluding Taiwan Province), distributed in 14 provinces (autonomous regions and municipalities directly under the Central Government), with a cumulative installed capacity of 567,000 kW and 1042 wind turbines. In 2003, 131 new units were added, with 98,000 kW and a growth rate of 21%. Currently, the domestic manufacturer of wind turbines has only 10.3% of the market share of domestic wind turbines, and foreign manufacturers have occupied most of the domestic market share. According to the wind power development plan prepared by the National Development and Reform Commission of China, the domestic wind turbine assembly capacity will reach 1 million kW in 2005, 4 million kW in 2010, 10 million kW in 2015, and 20 million kW in 2020 in 2030. With 80 million kWh, localization of wind power generation equipment will be realized as soon as possible, which has a very good market prospect.
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