Improved TIMS data reliability and precision with new ion source design

Abstract

The ion source design of the Triton and Triton Plus Thermal Ionisation Mass Spectrometer (TIMS) has been improved to reduce the frequency and intensity of high voltage electric sparking. Sparking can be caused by voltage flashover between the ion source components, resulting in rapid instability of the lens and acceleration voltages. This in turn leads to deflection of the ion beams in the analyzer and subsequently measurement biases, particularly on minor isotope detectors. Two prototype ion sources were engineered and tested to increase the condenser-to-ground flashover voltage without changing the geometry of any surfaces that would potentially adversely influence the ion beam transmission and focusing. The ion source enhancement facilitates better accuracy and precision of uranium total evaporation measurements. An external component test and analysis of natural uranium certified reference material 112-A has been used to validate the performance of three modified ion sources installed in two TIMS. The new design is commercially available.