Application of the Donkin formula in the theory of reflecting and turning devices

Electrostatic turning devices are electron- and ion-optical elements changing the direction of movement of a parallel monochromatic beam of charged particles by a given angle without affecting a beam’s parallelism. The trajectory similarity principle for electric fields homogeneous in Euler terms ensures the fulfillment of this property for the fields with a homogeneity of a zero power. The Donkin formula for 3D homogeneous harmonic functions produces extremely wide class of analytic expressions describing homogeneous electric potentials of a zero power. This paper considers the algorithm of synthesis of electrostatic turning devices that transform input parallel monochromatic beams into output parallel monochromatic beams. The algorithm is based on the Donkin formula and ensures beam stability for small deviations from the electric field’s symmetry plane.