2D calculation of parasitic fields in misaligned multipole electron-optical systems

Area of Science:

• Electron optics
• Computational physics

Background:

• 3D simulations for electron-optical component imperfections are computationally intensive.
• Existing methods require significant time and memory, and do not directly yield axial field functions.

Purpose of the Study:

• To develop a computationally efficient 2D perturbation method for calculating parasitic fields in misaligned multipole systems.
• To provide an alternative to slow 3D simulations for evaluating geometrical imperfections in electron optics.

Main Methods:

• A 2D perturbation method is introduced to find an equivalent potential perturbation.
• The method is analogous to Sturrock's but does not require potential differentiability.
• It is compatible with finite element method codes and applicable to electrostatic and non-saturated magnetic systems.

Main Results:

• The method accurately calculates axial field functions, with accuracy dependent on multipole components and geometry.
• It bypasses the need for 3D data and lengthy simulations.
• Results are suitable for determining parasitic imaging aberrations and evaluating mechanical tolerances.

Conclusions:

• The 2D perturbation method offers a significantly faster and less resource-intensive approach to analyzing electron-optical system imperfections.
• This technique facilitates the evaluation of mechanical design tolerances by providing essential axial field functions.