Optimising Ion Transport in a Thermal Ionisation Mass Spectrometer and Plasma Ion Source Using Monte Carlo Simulations
Date
2019-09-20
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Abstract
The controlled collimation of ion beams is of paramount importance in particle accelerators, high energy beamlines, and detector systems, as it determines the functionality, sensitivity and resolution of the instruments. In this thesis the ion source of a thermal ionization mass spectrometer (TIMS), comprised of a heated filament followed by a series of ion optical lenses, was modelled and Monte Carlo simulations were performed using SIMION. The potentials of three of the electrostatic lenses were optimized, in order to maximize the illuminated area of the exit slit. The optimization method employed achieved up to a 44 % increase in experimental signal intensity when compared to the existing manufacturer-provided lens tuning algorithm. 3D plots were effective in visualizing whether this new voltage configuration leads to a solution which lies in a local or global optimum, showing that the previous tuning technique was rarely successful in achieving the global optimum. This modelling and optimization approach was then used to aid the commissioning of a plasma ion source at the TITAN experiment at TRIUMF. The Plasma Ion Source (PIS), comprised of a heated filament followed by an anode, Einzel lens and X-Y correction steerers, was modelled and Monte Carlo simulations were performed. Optimising the voltage configurations in these simulations has proved successful in the commissioning of the PIS at the TITAN experiment in thermal mode, where ions from the source have been characterised using the time-of-flight method. The PIS will be able to deliver important calibration beams to TITAN’s experiments and will also enable off-line, high precision isotope composition measurements with the Multiple-Reflection Time-Of-Flight Mass Spectrometer (MR-TOF MS).
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Keywords
Monte Carlo, Optimisation, Ion optics, SIMION, Simulations, TIMS, TITAN, Plasma Ion Source
Citation
Flowerdew, J. A. D. (2019). Optimising Ion Transport in a Thermal Ionisation Mass Spectrometer and Plasma Ion Source Using Monte Carlo Simulations (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.