The determination of boundary conditions is visible, and three characteristic lines can be drawn from the inner point of the piping. Therefore, there are three groups of characteristic compatibility equations for solving three unknowns p, u, and Q. For the inlet boundary connected to the suction cup, only one characteristic line can be cited. There is only one set of characteristic compatibility relationships; the outlet boundary connected to the vacuum generator can only lead to two characteristic lines, so there are only two sets of feature compatibility relationships, so the supplementary relations of p, u, and Q need to be introduced. The boundary conditions for solving p, u, Q at different moments on the boundary.
The inlet boundary connected to the suction cup adopts the air chamber model[4,5], and there is pQC=constant, QV=m where V is the volume of the sucker and the pipe joint connected to the pipe; m is the gas quality within the volume. . The outlet boundary connected to the vacuum generator is based on the flow characteristics of the vacuum generator, and the relationship between the vacuum pressure p and the suction flow rate (QV=uA) is supplemented.
It can be seen that supplementing two sets of relations for the inlet boundary connected to the suction cup and adding a set of relations to the outlet boundary connected to the vacuum generator can obtain the p, u and Q values ​​at the inlet and outlet at different times.
Vacuum generator adsorption response time calculation and experimental verification According to the above theoretical model and solution method, the use of experimental flow characteristics can be used to calculate the vacuum generator system adsorption response time, in order to verify the correctness of the calculation results, vacuum Experimental verification of generator adsorption response time, see and.
The adsorption response time in the table refers to the time at which the suction cup reaches 63% of the final vacuum pressure pV. For the ZM072H vacuum generator and ZH20DS type vacuum generator under the different supply pressure flow curve, for the suction cup vacuum pressure curve with time. From this, it can be seen that the calculated results are in good agreement with the measured values, and the estimated value obtained from the empirical formula is quite different from the measured value.
Different types of vacuum generator flow curve. (a) ZM072H type vacuum generator flow characteristics; (b) ZH20DS type vacuum generator flow characteristics. Adsorption response time (ZH20DS type vacuum generator, the supply pressure is the adsorption response time without piping actual estimated value tp/ms.
[Conclusion] The model of the response time of the vacuum generator system was established by transient flow theory. The adsorption response time of different vacuum generators under different pipe sizes and lengths was calculated and compared with the actual measurements. The calculated and experimental values ​​were found. The agreement is quite good. It can be concluded that the calculation model established is correct. It overcomes the three shortcomings predicted by the empirical formula T=V@60/Q and lays a theoretical foundation for precision control in automation. .
The use of a pipe-type extraction electrode leads to a beam, and the geometric ratio of the drawn-out electrode has an important influence on the extraction of the beam. Through the establishment of the optimal extraction mathematical model, ion optics calculations were performed on the extraction system structure. The calculation results show that within a certain range of conductivity coefficient, different types of ions are extracted with different optimal geometric parameters. According to the calculation results of the extracted H beam and Ar beam, the geometric parameters of the extraction electrode suitable for extracting a plurality of ion beam currents are determined, and the extraction structure is designed and tested by combining various factors. Calculations and experimental results show that the lead-out electrode meets the requirements.
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