Data Set Overview : The Cassini Radio and Plasma Wave Science (RPWS) Langmuir Probe Sweep data set includes all thermal plasma information derived from Langmuir Probe voltage sweeps acquired in the inner magnetosphere and during Titan, Enceladus, and other icy satellite encounters for the entire Cassini mission. This data set includes spacecraft event time, radial distance from either Saturn or the target moon, electron number density, electron temperature, and spacecraft potential. Data are presented in ASCII text tables of fixed-length records for ease in data handling. A browse data set of PNG images is included, providing a graphical summary of the data for each inner magnetosphere pass or moon encounter. Parameters : This data set comprises spacecraft event time, radial distance from either Saturn or the target moon, electron number density, electron temperature, and spacecraft potential that were derived from RPWS measurements. Processing : Data in this data set were processed by the use of a number of software programs which assemble segmented mini-packets in the raw telemetry packets into complete sets, de-compress the data that were compressed by one of a number of compression algorithms by the RPWS flight software onboard, apply conversion lookup tables or algorithms to convert telemetry data numbers into physical units, and make any corrections required for antenna capacitive loading or other effects. See chapters 5 - 11 of the RPWSCAL document in the DOCUMENT directory for details on how the data included in this data set were calibrated. These data are calibrated using the best calibration tables and algorithms available at the time the data were archived. Should a significant improvement in calibration become available, an erratum will be noted in the erratum section. Later versions of the products may contain better calibrations. The sweep data itself consist of 0.5s long current-voltage characteristics (usually every 24s during Titan flybys) and in the voltage range +/-4V (for flybys above 1200km altitude, +/-32V has been used). The voltage sweeps are swept from both negative and positive voltage bias (i.e., two sweeps occur per 0.5s) to check for hysteresis artifacts. Very few were found, and corrected for. The analysis of the current-voltage characteristics has been made with Orbit Motion Limited (OML) theory using a non-linear least square fitting routine. The ions and photoelectrons part (negative bias) was first removed (linear fit), before fits were made for the electron part (positive bias). Up to three electron components were found, but only the dominant population results were kept for archiving. Sheath-Limited (SL) fits were made to confirm the validity of the output parameter results. SL features are detected in the sweeps near closest approach of Titan (dense plasma). Data : The archived data are the results of the OML analysis for each calibrated sweep of the Langmuir probe receiver (LPR) of the RPWS, presented as ASCII tables as a function of spacecraft event time. Ancillary Data : The Navigation and Ancillary Information Facility's SPICE kernels describing the position and attitude of Cassini and various solar system bodies as a function of time are archived separately. Coordinate System : The data in this data set are thermal plasma parameters derived from current-voltage relationships measured by the RPWS Langmuir probe. These parameters are presented as detected by the sensor and are not rotated into any other coordinate system. If desired the SPICE kernels can be used with the SPICE toolkit to convert from the spacecraft frame to virtually any frame which may be of use in analyzing these data. However, for most purposes, the parameters may be considered point measurements at Cassini (they are at most 0.5s long) and may be entirely adequate with no coordinate transformations at all. Media/Format : These data are supplied to the Planetary Data System as an online collection of files in a PDS volume directory structure or as a standard compressed archive, such as ZIP or TAR.GZ, of this collection.

Confidence Level Overview : This data set contains thermal plasma parameters derived from Langmuir probe voltage sweeps acquired by the Cassini RPWS instrument for the interval described below. Every effort has been made to ensure that all data returned to JPL from the spacecraft is included and that the calibration is accurate. Thermal electron output data will usually not be available, due to photoelectron current contamination, for number densities below 1 cm**-3 and/or for temperatures above 10eV, i.e. outside the ionosphere of Titan. Data < 1 cm**-3 and/or > 10 eV should be regarded as uncertain. Electron temperatures below 0.03eV should be regarded as uncertain, as the rms electric field surface variability of the spherical TiN coated probes is 0.015eV, and the number of sweep samples used for the temperature estimation becomes small (4-5 samples out of 1024 samples over +/-4V). The sampled probe current amplitude determines the confidence of the output parameters. For electron densities >100 cm**-3 the confidence level is better than 10% for the electron density and spacecraft potential, while it is better than 20% for the electron temperature. Review : The RPWS Langmuir probe sweep output data will be reviewed internally by the Cassini RPWS team prior to release to the PDS. The data set will also be peer reviewed by the PDS. Data Coverage and Quality : All data in the stated interval are included, to the best of our knowledge and attempts to determine completeness. In general, the RPWS/LPR instrument was operated continuously most of the time from SOI and forward, and gave higher resolution data during each moon flyby. Data gaps are due to spacecraft anomaly resolution or simply to downlink gaps, some of which were imposed by limitations on DSN station availability. The following Titan flybys have NO valid RPWS/Langmuir probe sweep data: T07 - no data T24 - no data T37 - no data T53 - nothing to see T60 - no data T66 - nothing to see T67 - nothing to see T72 - nothing to see T73 - no data T74 - nothing to see T76 - no data (data gaps) T79-T81 - nothing to see Data from T101 and forward are TBD. Limitations : Occasional RPWS Langmuir probe voltage sweeps have interference in individual sweep samples. These samples have been filtered away before analysis and should not pose a problem for the delivered output parameters. The RPWS HFR receiver produces interference signals in the LPR in certain negative bias voltage ranges. These do not affect the analysis on the electron (positive bias voltage side), and cause otherwise no significant error in the derived ion parameters. Thermal electron output data will usually not be available, due to photoelectron current contamination, for number densities below 1 cm**-3 and/or for temperatures above 10eV, i.e. outside the ionosphere of Titan. Data < 1 cm**-3 and/or > 10 eV should be regarded as uncertain. Electron temperatures below 0.03eV should be regarded as uncertain, as the rms electric field surface variability of the spherical TiN coated probes is 0.015eV, and the number of sweep samples used for the temperature estimation becomes small (4-5 samples out of 1024 samples over +/-4V).