Quadrupole mass filters are normally operated as narrow band pass filters by appropriate choices of rf and DC voltages corresponding to Mathieu a and q values near the apex of the first stability region. We add an auxiliary quadrupole excitation potential to the main drive voltage. As a result, stability islands appear on the ( a , q ) plane. The method of the islands mapping on the ( a , q ) plane is discussed in detail. The DC electric field's effect responsible for removing “shadowing” islands has been studied using a combination of analytic theory and computer modeling. We call a narrow stability region elongated along an iso- β x line an X-island. Two such stability islands were found where operation is possible without mass spectra interference when the DC potential is used. Those islands are formed by quadrupole potentials with relative excitation frequencies ν = β , ν = 1 ± β and ν = 2 ± β , where β << 1 . Many other stability X-islands are presented in detail and illustrated by their transmission contours. This data is necessary for experimental testing of the separation mode at those islands. The study demonstrates how to use X-islands to achieve relatively high resolution 4000-12,000 at the transmission of about 28-15%, respectively.

中文翻译：

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四极杆质量过滤器的稳定 X 岛

通过对应于第一稳定区域的顶点附近的Mathieu A和Q值，通常选择窄带质量滤波器通常为窄带通滤波器。我们在主驱动电压上添加了一个辅助四极激发电位。结果，稳定岛出现在 ( a , q ) 平面上。详细讨论了在(a,q)平面上的岛映射方法。已经使用分析理论和计算机建模的组合研究了负责消除“阴影”岛的直流电场效应。我们称沿等值β x 线拉长的狭窄稳定区为X 岛。发现了两个这样的稳定​​岛，当使用直流电势时，可以在没有质谱干扰的情况下进行操作。这些岛由具有相对激发频率 ν = β 、ν = 1 ± β 和 ν = 2 ± β 的四极电位形成，其中 β << 1 。详细介绍了许多其他稳定性 X 岛，并通过它们的传输轮廓进行了说明。该数据对于在这些岛上进行分离模式的实验测试是必要的。该研究演示了如何使用 X 岛分别在约 28-15% 的透射率下实现相对较高的分辨率 4000-12,000。