Pipeline Design for Venus Mass Spectrometer Using Axial Dispersion Residence Time Distributions

Precision atmospheric measurements from the Deep Atmosphere Venus Investigation of Noble Gases, Chemistry, and Imaging (DAVINCI) mission will be used to describe columnar chemical variations for a broad range of atomic masses, relative abundances of trace species, and isotope ratios of noble gases. The gas processing system (GPS) in DAVINCI’s Venus Mass Spectrometer (VMS) is responsible for transferring and enriching gases delivered to the quadrupole mass spectrometer (QMS) at the heart of VMS. Flow simulations were performed with simplified computational and analytical models to inform trade studies and examine the nuances of timestamping samples admitted into the QMS. We evaluate the statistical latency of samples in relation to the altitudes from which they would be retrieved. Samples are considered concomitant when the residence time of the atmosphere is minimized and can be mapped to a corresponding altitude range. By computing the fraction of fluid parcels with science-compliant residence times, preliminary results indicate that the GPS could operate at 95% measurement concomitance with altitude on average. The method applies to laminar pipe flow without convective mixing, diffusion, or secondary friction losses. For continuous sampling, targeting a high level of concomitance alleviates some aspects of data uncertainty, including altitude (i.e., temporal) smearing.