Research On Fringe Field Analysis And Pumping Speed Measurement Of Miniature Sputtering Ion Pump

With the development of science and technology in recent years,the application fields of sputtering ion pumps have been expanded.Sputtering ion pumps are also developing in the direction of miniaturization.Miniature sputtering ion pumps are increasingly used in aerospace products,electronic devices,and scientific instruments.For example,high-precision electrostatic levitation accelerometers,spectrometers,atomic clocks and many electronic devices require miniature sputtering ion pumps to maintain ultra-high vacuum to ensure normal operation.Although the research on the miniature sputtering ion pump is gradually increasing,there is a lack of systematic analysis and research on the relationship between the internal discharge characteristics and the pumping speed during the pumping process of the miniature sputtering ion pump.It is not detailed enough to discuss the experimental measurement method of pumping speed less than 10-3 m3/s.Therefore,this paper decided to use numerical simulation and experimental measurement methods to study the influence of the fringe electric field and magnetic field of the miniature sputtering ion pump on the pumping speed.First,in order to study the pumping speed characteristics of the miniature sputtering ion pump in N2,Ar,and He,it was decided to use COMSOL software to simulate the discharge process of the miniature sputtering ion pump,and analyze the influence of the fringe electric field and magnetic field of the miniature sputtering ion pump.The magnitude of the degree of rapid change.The miniature sputtering ion pump has different pumping mechanisms for different types of gases,and the discharge parameters obtained by numerical simulations are combined with their respective pumping mechanisms to explain the reasons for the changes in the N2,Ar,and He pumping speed curves.Next,the micro-vacuum pump pumping speed calibration device was improved,and the baffle orifice of the dynamic conductance method was redesigned to meet the purpose of measuring small pumping speeds.The dynamic conductance method and flowmeter method used in the experiment were introduced,the advantages of the two methods are compared,and the specific steps of the measurement process are given.In order to provide a stable and small flow for the miniature sputtering ion pump,the pressure rise method is used to measure the conductance of the flowmeter orifice in N2,Ar,and He.The pumping speed of the ionization gauge was measured to optimize the pumping speed measurement results.Then,through experiments,the pumping speed curves of the miniature sputtering ion pump in N2,Ar,and He were obtained.The pumping speed of the miniature sputtering ion pump in N2 remains unchanged under the pressure range 10-4～10-3 Pa.When the pressure is 10-4 Pa,the pumping speed obviously decreases with the decrease of pressure.The pumping speed of the miniature sputtering ion pump in Ar fluctuates within a certain range.The pumping speed of the miniature sputtering ion pump in He gradually decreases with the increase of pressure.The uncertainty evaluation results of dynamic conductance method and flowmeter method are respectively given,which are 8.9%and 11.6%respectively.The fringe field of the miniature sputtering ion pump includes electric field and magnetic field.As the voltage increases,the pumping speed of the miniature sputtering ion pump increases.Finally,according to the ideal gas equation of state,a method for calculating the pumping speed of the miniature sputtering ion pump was given.The parameters such as the energy,angle,and incident position of the ion incident on the cathode plate obtained by the numerical simulation were brought into the formula to calculate pumping speed of the ion pump.The theoretical calculation results are in good agreement with the experimental measurement results.In this paper,the pumping speed of the miniature sputtering ion pump is measured for the first time in different kinds of gases,and the results of the numerical simulation are in good agreement with the experimental results.The experiment measured a pumping speed of less than 10-5 m3/s,and realized the measurement of a low pumping speed.The comparison results of the flowmeter method and the dynamic conductance method are given.The content of this paper has reference significance for the improved design of sputtering ion pump.The content of this article can also be used as a reference for other small pumping speed measurement projects when problems are encountered.