Numerical Simulations and the Design of Magnetic Field-Enhanced Electron Impact Ion Source with Hollow Cylinder Structure.

Guochen Qi,Di Tian,Guolun Gao,Guangda Liu,Chunling Qiu,Tao Long

doi:10.1155/2020/2809485

Abstract

An electron impact ion source-adopted magnetic field-enhanced technology has been designed for enhancing the electron intensity and the ionization efficiency. Based on the ion optic focus mechanism, an electron impact ionization source was designed, and the electron entrance into the ionization chamber was designed with a hollow cylinder structure to improve the ion extraction efficiency. Numerical simulation and optimal geometry were optimized by SIMION 8.0 to provide higher electron intensity and ion transmission efficiency. To improve the electron intensity, the influence of the filament potential and magnetic intensity was investigated, and the values of 70 eV and 150 Gs were chosen in our apparatus. Based on the optimal parameters, the air in the lab and oxygen gas was detected by the homemade apparatus, and the ion intensity was detected in the positive and negative ion modes, respectively. The homemade electron impact ion source apparatus has the potential to enhance ionization efficiency applied in the mass spectrometer ionization source.

Highlights

Electron beam is a widely used source for chemical composition analysis [1] and material characterization instrument [2]
E released electron intensity from the cathode filament is an important indicator for evaluating the electron impact (EI) ionization source, which is related to the instrument performance [13]. e most direct way to improve the ionization efficiency is to increase the filament current of the EI ionization source
Electron Intensity and Electron Energy. e released electron intensity from the cathode filament is an important indicator for evaluating the EI ionization source, which is related to the apparatus performance

Summary

Introduction

Electron beam is a widely used source for chemical composition analysis [1] and material characterization instrument [2]. E released electron intensity from the cathode filament is an important indicator for evaluating the EI ionization source, which is related to the instrument performance [13]. To enhance the electron intensity and analyte molecules’ ionization efficiency, a magnet was placed behind the filament to create a homogeneous magnetic field inside the chamber.

Results

Conclusion