四极滤质器中离子振荡周期影响因素研究

Study on factors influencing ion oscillation period in quadrupole mass filter

位于四极滤质器稳定区中的离子,在x、y方向上的振荡幅度近似为周期性变化。取两个相邻最大振幅之间的时间间隔作为离子振荡周期。对于由射频激励信号(正弦波形式)驱动的四极场,离子振荡周期受到射频频率、工作点a、q值等参数的影响。本文通过对四极场中离子运动轨迹的数值分析,发现离子振荡频率随射频频率的变化呈线性关系,随工作点a、q值的变化近似于幂函数关系。

When ions move into stable zone of a quadrupole mass filter,their oscillation amplitudes in x and y directions change approximately periodically.Ion oscillation period is defined as the time span between two adjacent largest amplitudes.For quadrupole field excited by sinewave RF signal,ion oscillation period is influenced by parameters such as RF frequency,and a and q values.Through numerical analysis of the ion trajectories in quadrupole field,it is found that there is a linear relationship between the RF frequency and ion oscillation period,and an approximate power function relationship between ion oscillation period and a and q values.