The design of electrostatic quadrupole zoom lens for fixed multi-collector system at mass spectrometer

⿢A theoretical model for the design of Electrostatic Quadrupole Zoom Lens has been established, and validated by SIMION.⿢Segment-type quadrupole zoom lens with a better flexibility has been proposed and investigated.⿢Study shows electrostatic quadrupole doublet is CD-type for m > 1.0, and DC-type for m < 1.0.⿢Study shows the theoretical model performs well if the first order approximation is satisfied.⿢Voltage corrections can compensate dissatisfaction of paraxial approximations somehow, giving a satisfactory performance.

In order to measure different isotopes with fixed multi-collectors at a Mass Spectrometer conveniently, a zoom lens with two electrostatic quadrupoles is chosen to adapt the dispersions from different isotopes. A design method of such a zoom lens is introduced in this paper. Based on theoretical modelling results, validation of zoom effect and focusing performance has been carried out through SIMION simulation of two different electrostatic quadrupole devices: pole-type and segment-type. Then, electric voltage corrections have been applied considering the inconsistencies. Finally, the design requirements are satisfied.

102A designed method of zoom lens containing two electrostatic quadrupoles is introduced to adapt the dispersion of different isotopes and to measure them by fixed multi-collector system at mass spectrometer.