射频离子阱中离子囚禁的模拟和实验

Simulation and experiment on confinement of ions in radio-frequency ion trap

根据自己研制的激光离子源射频离子阱质谱仪的构造和工作条件，采用ＳＩＭＩＯＮ（６．０）程序，模拟了阱离子各种参数和工作条件对离子囚禁的影响。模拟结果显示，在阱内充入足量（０．１３３Ｐａ）的缓冲气体（氦气）对离子的囚禁会起到很重要的作用。阱内的氦气通过和离子的碰撞，能有效地降低离子的动能，缩小离于在阱内的运动范围。因此，在氦气的作用下，注入阱内的离子只要达到一定的动能（＞１０ｅＶ），就能被有效地囚禁。初步的实验证实了模拟结果。

The effects of the paramenters and working conditions of radio-frequency ion trap mass spectrometer on the confinement on the confinement of ions has been simulated using the ion optical simulation program SIMION6.0. The mass spectormeter is a home-made instrument with laser desorption ion source. The simulation results reveal that sufficient amount of quantified buffer gas (helium) has very impor tant effects on the trapping of ions. The kinetic energy and moving space of ions in the trap can be significantly reduced by colli sion with helium gas. If the injected ions have reached a certain kinetic energy (>10eV), they can be effectively confined in the trap due to collision with helium gas. The preliminarye experiments have confirmed the simulation results.