Ion optics with electrostatic lenses

Ion optics with electrostatic lenses is presented using the standard matrix formalism of magnetic ion optics. We introduce the paraxial ray equation which is appropriate to systems with rotational symmetry. The first-order solutions of the paraxial ray equation are derived. The resulting transport matrices can be used to study systems with acceleration tube lenses, aperture lenses, einzel lenses and dc accelerators. The analogy with geometrical optics is discussed. Beam transport and phase ellipses are described using the so-called σ matrices. The equations of the longitudinal transport matrix are derived. Besides rotational symmetric elements, electrostatic quadrupoles and electrostatic deflectors are also presented. The effect of space charge forces is discussed.