Paraxial parameters and aberration of seven-electrode axisymmetric cathodic lend

This paper cites the results of numeral researches and analyses paraxial parameters and dimensional aberrations of seven-electrode axisymmetric cathodic lens.
As is known, the majority electron-optic devices and hardware, ion-beam technological devices, nano and microelectronics, mass analyzers, electron-optic transformers and other analytical devices’ technical characteristics depend on the quality of focusing.
In the present paper numeral researches and the analysis of paraxial parametres and aberration of seven-electrode axisymmetric cathodic lens, which consists of plate cathode and six cylindrical electrodes with equal value of their diameters, arranged sequentially and in alignment, were made.
In cylindrical system of coordinates , the cathode is situated perpendicularly to the principal optic axis and indicating the coordinate value starts from the surface of cathode. Generatrices of cylindrical electrodes (solid of revolution) are parallel to axis . Cathode potential value is zero, potentials on first, second, third, fourth, fifth and sixth cylindrical electrodes are designated as , , , , and pro tanto. In view of rotational symmetry of electrodes parameters of the lens being investigated does not depend on coordinate .
Here means coordinates of beam crossover of charged particles, which is formed by investigated lens.
The result of calculations which was made by computers helped us to define the correlations of lens parameters (sizes of electrodes and its potential) where everything fulfills the conditions (8). The results are shown in the shape of graph.
Comparing received data with the results of calculation three and five-electrode axisymmetric lens indicates that increase in quantity of electrodes might make some improvements for selected types of aberration. However, nearly all their aberrational parameters have approximately same order. On the other hand, comparison of both results with analogous to them transaxial (bi-symmetric) elements, show that aberration value of transaxial lenses in horizontal direction is considerably less than analogical aberration value inherent to axisymmetric lenses [4]. Hence, in some cases using transaxial focusing elements makes a lot more better conditions to formulate electric and ionic fluxes with necessary parameters of beam focusing.