一种基于数值分析的矩形离子阱仿真优化方法

提出了一种对矩形离子阱进行仿真设计和优化的方法。该方法以数值分析为基础,对离子在矩形离子阱中的运动进行分析,得到相应的离子运动二阶微分方程。然后使用数值分析的Runge-Kutta法,对此二阶微分方程进行求解,可以得到理想状态下离子在离子阱中稳定的条件,从而完成对矩形离子阱的设计和优化。采用本方法,设计并优化了一种矩形离子阱,质量范围最大为260 amu/e,使用乙醇作为目标样品,紫外灯源作为离子源,法拉第筒作为检测器,对该矩形离子阱进行了质谱实验,成功得到了质谱结果,验证了所提出的数值分析仿真优化方法的实用性和正确性。本方法简单易行,便于修改,针对性强,可对多个参数使用循环遍历的方式来寻找最优值,特别适用于对未知结构或参数的探索研究。以此方法为基础可开发离子运动仿真软件,有很好的应用前景。

A Simulation and Optimization Method Based on Numerical Analysis for Rectilinear Ion Trap

A simulation and optimization method for rectilinear ion trap (RIT) was introduced. The protocol for this method is implemented in principle according to verification experiments. On the basis of numerical analysis, second-order differential equations were obtained to describe the movements of ions in the RIT. The equations were solved by the Runge-Kutta method and the conditions for stability of ions in the ion trap were obtained under ideal conditions which represented the ability of the RIT to catch and trap the ions. An RIT was designed and optimized according to the optimal conditions. In this study, ethanol vapour was ionized by a UV discharge lamp and the RIT was used as a mass analyzer during the verification experiment. The ethanol ions were detected by a Faraday cup. The mass spectrum of ethanol was obtained successfully with mass range up to 260 amu/e and the method proved to be practical and correct. The numerical analysis is simple, well-targeted and easy to modify. The loops could be used to find out the optimal structure and parameter, so the method is suitable for the research on RIT. Furthermore, simulation software could be developed based on it. The method is of high manoeuvrability and possesses a vast range of applications prospect.