RF-driven ion source for accelerator mass spectrometry with plasma modeling and validation test stand

Abstract

A duoplasmatron, an ion source typically used in accelerator mass spectrometry, was tested at Dongguk University, Korea, within its radiocarbon dating facility that incorporates a mini carbon dating system. The facility developed a prototype ion source for analyzing high-level ¹⁴C samples. However, the duoplasmatron exhibits limitations in terms of reliability and efficiency when used for carbon counting in gas samples. To address these limitations of duoplasmatron with plasma persistence and filament lifetime, a reliable and low-maintenance RF-driven ion source was proposed, designed and fabricated. This study focuses on plasma modeling within the RF ion source to facilitate simulation studies and predict plasma conditions. An RF ion source test stand was installed, enabling the direct injection of CO₂ gas to verify the performance of RF components and confirm plasma ignition. RGA scanning revealed the elemental species generated during the plasma ignition, indicating an increase in the relative pressure intensity of the target elements. The results of the RF ion source plasma simulations and the test stand validation through a residual gas analysis, comparing the simulation and RGA scanning results are presented in this paper.