A New Ion Optical System for High Resolution High Sensitivity Mass Spectrometer

Abstract

A new type of double focusing mass spectrometer is proposed. The apparatus consists of a hybrid electric field, a Q-lens and a homogeneous magnetic field with curved boundaries. It has focusing nature of both second order and stigmatic, besides the image magnification is only 0.1. Therefore, very high sensitivity is expected at high resolution because 10 times wider source slit is possible to use comparing with the conventional mass spectrometer. The distinguishing feature of this ion optical system is that the electric field is divided into two parts, one is a diverging field with c>2 and the other a converging field with c<2. The first electric field makes a small virtual image and this virtual image is focused by the second electric field at the exit of the electric field. The image aberration due to the influence of the fringing field is reduced by the small beam size at the boundary. Several examples of the ion optical systems are described.