In the design of devices containing beams of charged particles, it is helpful to know how the particle's trajectories will be modified by small displacement of electrodes. This paper describes a method to predict the perturbation of particle trajectories. In this methodology, the derivative of the potential is deduced from the results of finite element computation. The equation of motion is solved to calculate the perturbation of particle trajectories separately. An example of a perturbation trajectory in an electrostatic lens is presented.

In this paper, the coma of the fifth-order aberration at a large deflection angle has been analyzed by using multipole field theory. The dilemma effect exists in the comas of fifth-order aberration. The dilemma effect, whose value D3 is constant and independent of the 10-pole field, is the linear combination of coma aberrations. The coma of the fifth-order aberration is corrected by adjusting the 10-pole field distribution when Dr is zero or small. The factors that influence the dilemma effect have been calculated and analyzed.

In the field emitter array, there is a fringe field surrounding the emitter array. The fringe field and the interactive field between different tips will influence the emission uniformity of the emitter array. This paper studies the influences of the fringe field and the interactive field on the emission performance of a diode emitter array. The variations of the emission currents versus the width of the margin of the array are given. From these results, the influences of the fringe field on the emissions of the center tips and the corner tips are obtained. This paper also analyses the dependence of the fringe field and the interactive field on the cathode-anode distance and the tip-to-tip spacing.

In the application of field emitter arrays, it is useful to understand its emission performance. This paper calculates the electric field of a diode emitter array in three-dimensional space. From this calculation, the emission uniformity of a diode array is studied. The dependance of the tip-to-tip spacing and of the cathode-anode distance on the uniformity of the array is also analyzed. The pressure sensor based on the diode model is simulated. From the dependence of the emission current for different tip densities, the influence of the emission uniformity can be obtained. (1999 Published by Elsevier Science B.V. All rights reserved.