Shimadzu Corporation

Norihito Inatsugu

Hiroaki Waki

A mass spectrometer according to the present invention includes an ion lens composed of an even number of virtual rod electrodes positioned separately around the ion beam axis C, where each of the virtual rod electrodes is composed of a plurality of separate metallic plate electrodes aligned in a row. For example, the virtual rod electrode consists of five lens electrodes aligned in a row parallel to the ion beam axis C. A voltage composed of a DC voltage and a high frequency AC voltage superimposed thereon is applied to each of the plate electrodes where the DC voltage is changed according to the position of the plate electrode while the high frequency AC voltage is the same irrespective of the position. Ions travelling through the ion lens oscillates transversally due to the electric field generated by the high frequency AC voltage and converge on the focal point F of the ion lens. There, the ions gain kinetic energy from the potential gradient due to the DC voltages, whereby the ions are accelerated. Thus, the ions keep travelling without being displaced too much from due converging paths even when they collide with molecules of residing gas, and enter the section behind the ion lens through the orifice of the skimmer Thus, the convergence and acceleration of ions are effectively performed even when the pressure in the first interface chamber is as high as near atmospheric pressure.

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Kyoto, Japan

Norihito Inatsugu