Implications from secondary emission from neutral impact on <i>Cassini</i> plasma and dust measurements

We investigate the role of secondary electron and ion emission from impact gas molecules on Cassini Langmuir Probe (RPWS-LP, or LP) measurements in ionosphere Saturn. add a model currents, based laboratory data comet 1P/Halley, to equations used derive plasma parameters LP bias voltage sweeps. Reanalysing several hundred sweeps Grand Finale orbits, we find reasonable explanations for three open conundrums previous studies Saturn ionosphere. an explanation observed positive charging spacecraft, possibly overestimated ionospheric temperatures, excess current reported. For analysed detail, do not (indirect direct) evidence dust having significant charge-carrying Saturn's also produce estimate H2O number density last six revolutions through higher detail than reported by Ion Neutral Mass Spectrometer (INMS). Our analysis reveals that is highly structured latitude across all final revolutions, with mixing ratios varying two orders magnitude one order between altitude. The result generally consistent empirical photochemistry balancing production H+ ions loss charge transfer e.g., H2O, CH4 CO2, which water vapour appears as likeliest dominant source signal terms yield concentration.