The present work puts forward an electrostatic optical device for application in an ion-optical system. A design has been achieved computationally for a multi-electrode immersion lens of low relativespherical and chromatic aberration coefficients with the aid of thefollowing suggested expression for the potential field: U(z)=[(a*z)/(z2+c)]+b where a, b, and c are constants, z is the optical axis, and U(z) is the axial potential distribution. These results suggest that operating the proposed lens under zero magnification conditions is more favorable. Therefore, the proposed expression for the potential distribution is recommended for representing an electrostatic immersion lens of low relative chromatic aberration coefficient.

Electrostatic lenses --- Ion-optical system --- Spherical aberration --- Chromatic aberration