| 摘要 |
The quadrupole mass spectrometer has four conventional rod-shaped poles symmetrically located about the ion injection axis. Opposite pairs of rods are interconnected and connected to an rf voltage source. A shield having a circular aperture is located at the output end of the rods to assure the stoppage of low mass particles. In addition, a stopping element also preferably circular is located on the axis at the output to assure the stoppage of heavy particles. A pair of grids incorporating the stopping element, are sequentially located at the output, normal to the axis, the first is connected to a dc voltage source to accelerate the remaining particles through the fringing field of the quadrupole and the second is connected to a dc voltage source to subsequently decelerate the particles.
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