2.2.2 spase://SMWG/Instrument/SanMarco-DL/IVI Ion Velocity Investigation 2019-05-05T12:34:56Z This investigation uses a planar retarding potential analyzer, designed to obtain measurements of relative thermal-ion velocity, plasma density, and ion temperature. The ion angle of arrival can be determined by use of a square aperture collimator and a split collector. Together with knowledge of spacecraft motion, this allows computation of the three-dimensional thermal-ion motion along the orbital path. Plasma density and temperature are calculated by interpretation of the volt-ampere profile produced by the instrument for a given impressed voltage pattern on the grids and collector. Ion velocity measurements are obtained once each spacecraft spin period (10 s). spase://SMWG/Person/William.B.Hanson PrincipalInvestigator NSSDC's Master Catalog https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1988-026A-03 Information about the Ion Velocity Investigation on San Marco-DL RetardingPotentialAnalyser IonDrift Ion Velocity Investigation on San Marco-DL spase://SMWG/Observatory/SanMarco-DL