Simulation of Rydberg Ionization in Atomic Beams for FIB Optimization

TL;DR

This paper presents a simulation framework for optimizing Rydberg ionization in atomic beams to improve focused ion beam (FIB) performance, combining detailed modeling of excitation, ionization, and beam properties.

Contribution

It introduces a novel integrated simulation approach using Lua and SIMION to analyze and optimize Rydberg ionization processes for FIB applications.

Findings

Reduced axial energy spread achieved in simulations

Identified key parameters influencing ion beam quality

Demonstrated potential for next-generation ion source development

Abstract

This study explores the excitation and ionization of an atomic beam as a pathway to optimize focused ion beams (FIBs) for high-precision applications. Leveraging the unique advantages of Rydberg excitation followed by field ionization -- specifically its ability to minimize velocity and position dispersions -- we present a method to generate ion beams with good performance at low energies. A custom Lua program, integrated into the SIMION simulation platform, models the intricate processes of particle distributions, laser excitation, and Rydberg ionization. This integrated approach incorporates essential parameters such as excitation and ionization rates, Stark shifts, Doppler effects, and electric fields, enabling a detailed analysis of ion beam properties. Our simulations demonstrate the influence of critical factors such as the chosen Rydberg state, ionization region characteristics, and velocity dispersions on the final ion beam quality. By optimizing these parameters, we achieve significant reduction of the axial energy spread and the longitudinal extent of the ionization region. This framework bridges theoretical modeling and experimental validation, offering a comprehensive toolkit for the development of next-generation ion sources and advancing FIB technologies across various scientific domains.