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Microchannel Plate (MCP) is a component that multiplies electrons distributed in two-dimensional space. It is composed of millions of micro channels with the capability of secondary electron multiplication. The incident electrons bombard the inner wall of the channel, generating more secondary electrons than the incident electrons, emitting out of the inner wall surface. Under the effect of the electric field, the electrons accelerate forward and continue to hit the inner wall of the channel. After many such collisions, the electronic output at the output end of the channel is tens of millions of times. It has the characteristics of high gain, low noise, high resolution, broadband, low power consumption, long life, etc. Because atomic clocks have such characteristics as extremely high accuracy, excellent long-term stability, excellent daily stability performance, and no frequency drift, they play an irreplaceable important role in the basic measurement of time and frequency quantities, high accuracy measurement of physical constants, time keeping, time service, space navigation and positioning and other fields. In order to achieve long time and large enough signal multiplication, the MCP for atomic clock must be larger in size and thinner in thickness and must be able to work continuously under high voltage and high vacuum conditions. Therefore, MCP is required to have higher flatness, parallelism and surface finish, to minimize the possibility of device failure caused by spark and discharge under high electric field of MCP, and to obtain better signal-to-noise ratio to meet high-precision time and frequency measurement. In order to ensure the performance of large size and ultra-thin MCP, high-quality double-sided polishing technology is necessary. This technology adopts double-sided grinding and polishing, which theoretically guarantees the parallelism and flatness of large and ultra-thin MCP. However, while reaching the high-quality surface, due to the large amount of material removal during the grinding and polishing process, the surface activity is increased, and the adsorption is strong. After polishing, the large and ultra-thin MCP surface often remains stubborn pollutants that are difficult to clean. These pollutants are easy to form emission points under high field strength, resulting in scrapping of the whole machine. Traditional cleaning methods cannot remove these stubborn surface contaminants, and the large size of MCP increases the cleaning difficulty, so it is necessary to conduct research on the cleaning technology of large size and ultra-thin MCP surface. In this paper, optical microscope, scanning electron microscope and other analysis and characterization methods are used to analyze the composition and morphology of the surface contaminants on the large size ultrathin microchannel plate after double- sided polishing, and to study the influence of different cleaning technologies on the surface quality of the polished microchannel plate, so as to find the best cleaning method. The research shows that in the tri frequency ultrasonic cleaning, using absolute ethanol as the medium, the nano bubbles generated by the nano bubble generation device can effectively remove a large number of pollutants on the surface of large and ultra-thin microchannel plates, thus meeting the high-quality use standard for atomic clocks.
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