Relationship Geometric Error And Mass Resolution Quadrupole Mass Analyzer

Quadrupole mass spectrograph is one of the maturest and the most widely used mass spectrograph presently. The quadrupole mass analyzer (quadrupole for short) is the hard core of the quadrupole mass spectrograph, and its geometric errors have a direct effect on the performance of the mass spectrograph. The manufacture of the quadrupole mass analyzer involves massive high-precision geometric parameter control and has much difficulty in technics, so its cost is very high, therefore studying the impact of different kind of geometric errors on its mass resolution and summarize the regulation, thus emphasizing on the control of key parameters in the process of manufacture, optimizing the machining technics, producing high-performance quadrupole mass analyzer, reducing the production cost, measuring and grading the products properly, is of great importance.(1) The numerical simulation of the2-dimension model of the quadrupole mass analyzer. The method of calculating the electric field intensity was established using Equivalent Charge Method; the trajectory expression of the ions in the field circle is listed and then solved by numerical method. The mass spectrum peak and the q-a stable diagram is served as the evaluation tools, and their calculation method is studied. The way of calculating the mass solution by the mass spectrum peak is presented.(2) The simulation program of the2-dimension quadrupole mass analyzer is written. The quantificational simulation result of the infection of displacement error and diameter error is presented.(3) Based on the2-dimension model of the quadrupole, the geometric model of the3-dimension quadrupole is simplified. The Subsection Simulation Method is proposed and its calculation results are compared with the ion optical simulation software Simion. The fast and high-accuracy simulation of the3-dimension model is realized, and the corresponding program is written. Several typical geometry errors of the3-dimension model are studied using this program.Through the researches above, a simulation program which can get the mass solution of a quadrupole from its geometric parameter is established, and the influence of most geometry errors on the mass solution of the quadrupole can be studied by the program. The simulation results show that the diameter error of the rods and the roundness error field circle have the most significant influence on the mass solution, and in the axial direction of the quadrupole, the mass solution of the whole quadrupole is mostly infected by the section whose mass solution is the lowest of all, if only the spatial low-frequency errors are considered. The numerical simulation results are supported by the geometric and mass spectrum measurement results of the existing samples.