Design and Characterization of a Novel Hybrid-field Ion-Guide as part of a TOF MS Platform

摘要

A novel design of a Radio-Frequency (RF) octapole ion guide arrangement forming multiple longitudinal segments is described using gas dynamics calculations and ion optics simulations. The ion guide is constructed and further evaluated experimentally on a prototype orthogonal Time-of-Flight Mass Spectrometry (TOF MS) platform. The octapole is structurally configured to produce multipolar RF field distributions of different order throughout the geometry. The octapolar field is formed at the entrance to enhance acceptance, which is particularly useful for capturing ions entrained in diffusive jet flows emerging from narrow pressure limiting apertures, while the quadrupolar field established toward the exit compresses radial phase and confines the ion beam on axis. Investigations using ion optical simulations incorporating realistic low pressure gas flows provide insights to help interpret experimental results and improve design and performance.