The correction of image aberrations of second order for mass or energy separators consisting of one single magnetic sector field

Abstract

Image aberrations of second order are presented for mass separators consisting of one homogeneous or inhomogeneous 1–3) magnetic sector field, whereby the influence of the fringing fields 4, 5) are included in these expressions. Using a graphical method similar to linear programming techniques the derived aberrations can be corrected by proper choice of the curvatures of the entrance and exit boundaries of the magnet. As an example finally such a correction is carried out for a stigmatic focusing symmetric mass separator using a magnetic field with the inhomogeneity factor n = 0.5 and with perpendicular entry and exit of the ion beam into and out of the sector field.