The CHopper (Comet Hopper) was a proposal for a NASA mission to visit comet 46P/Wirtanen. A time of flight ion and neutral mass spectrometer (CHIMS) was developed especially for the proposed mission and was to be mounted on the Chopper spacecraft. CHIMS was to establish the composition and isotopic ratios of the comet's volatile components. Since NASA selected the InSight mission, CHIMS had been proposed for other missions: LIFE, Life Investigation For Enceladus, a low-cost sample return mission to Enceladus and Castalia, an ESA medium-sized mission to explore the Main Comet Belt. CHIMS was in need of fine tuning; the scientific demand of having accurate detection efficiency, combined with high performance make it necessary to rigorously test and calibrate instruments to operate at their optimum level. The goal of this work is to improve the performance of the ion source by applying simulation and optimization techniques to the CHIMS lab prototype. The results show a positive outcome, and propose a number of future modifications that should help obtain the desired results for any future missions.