Voyager 2 Plasma Science Experiment (PLS) Jupiter Data Bundle Plasma Derived Electron Moments 96.0 Second Jupiter Data Description PDS3_DATA_SET_ID = VG2-J-PLS-5-SUMM-ELE-MOM-96.0SEC-V1.0 PDS3_DATA_SET_NAME = VG2 JUP PLASMA DERIVED ELECTRON MOMENTS 96.0 SEC V1.1 START_TIME = 1979-07-06T00:00:42.687 STOP_TIME = 1979-07-09T23:59:06.436 ORIGINAL_DATA_SET_RELEASE_DATE = 1997-12-01 PRODUCER_FULL_NAME = JOHN D. RICHARDSON References: Bridge, H.S., J.W. Belcher, R.J. Butler, A.J. Lazarus, A.M. Mavretic, J.D. Sullivan, G.L. Siscoe, and V.M. Vasyliunas, The Plasma Experiment on the 1977 Voyager Mission, Space Sci. Rev., Vol. 21, p. 259, 1977. Bridge, H.S., J.W. Belcher, A.J. Lazarus, J.D. Sullivan, F. Bagenal, R.L. McNutt, K.W. Ogilvie, J.D. Scudder, E.C. Sittler, V.M. Vasyliunas, and C.K. Goertz, Plasma Observations Near Jupiter: Initial Results from Voyager 2, Science, Vol. 206, p. 972, 1979. Scudder, J.D., E.C. Sittler, and H.S. Bridge, Survey of the Plasma Electron Environment of Jupiter: A View from Voyager, J. Geophys. Res., Vol. 86, p. 8157, 1981. Sittler, E.C., Jr., and D.F. Strobel, Io Plasma Torus Electrons: Voyager 1, J. Geophys. Res., Vol. 92, p. 5741, 1987. Collection Overview -------------------- This data collection contains derived values of the electron density and moment temperature at Jupiter during the Voyager 2 encounter in the PLS voltage range (10-5950 eV/q). Adjacent low and high energy electron measurements are combined to form a composite spectra which is used for the moment calculation. The moment calculations are performed as described in Scudder et al. These assume isotropic distributions and correct for positive spacecraft charge when applicable and interpolate electron spectra below the 10 eV instrument threshold before performing the integration over velocity. Data format: column 1 is time (yyyy-mm-ddThh:mm:ss.sssZ), column 2 is the moment density in cm^-3, column 3 the temperature in eV. Each row has format (a24, 2(1x,1pe9.2)). Values of -9.99e+10 indicate that the parameter could not be obtained from the data using the standard analysis technique. Processing Level Id : 5 Software Flag : Y Processing Start Time : UNK Processing Stop Time : UNK Parameters ========== Sampling Parameter Name : TIME Data Set Parameter Name : ELECTRON DENSITY Sampling Parameter Resolution : 96.000000 Sampling Parameter Interval : 96.000000 Minimum Available Sampling Int : 96.000000 Data Set Parameter Unit : CM-3 Sampling Parameter Unit : SECOND A derived parameter equaling the number of electrons per unit volume over a specified range of electron energy. Different forms of electron density are distinguished by method of derivation (Maxwellian fit, method of moments) or by some selection criteria (ie., hot electron and cold electron density). In general, if more than one electron component is analyzed, either by moment or fit, a total density will be provided which is the sum of the electron densities. If the electrons do not have a Maxwellian distribution the actual distribution can be represented as the sum of several Maxwellians, in which case the density of each Maxwellian is given. Sampling Parameter Name : TIME Data Set Parameter Name : ELECTRON TEMPERATURE Sampling Parameter Resolution : 96.000000 Sampling Parameter Interval : 96.000000 Minimum Available Sampling Int : 96.000000 Data Set Parameter Unit : EV Sampling Parameter Unit : SECOND A derived parameter giving an indication of the mean energy/electron, assuming the shape of the electron energy derived spectrum to be Maxwellian. Given that the electron energy spectrum is not exactly Maxwellian, the electron temperature can be defined integrally (whereby the mean energy obtained by integrating under the actual electron energy spectrum is set equal to the integral under a Maxwellian, where the temperature is a free parameter for which to solve), or differentially (whereby the slopes of the actually electron energy spectrum at various energies are matched to the slopes of a corresponding Maxwellian). The temperature parameter is often qualified with a range of applicable energies. Temperatures can be angularly anisotropic. If the electrons do not have a Maxwellian distribution the actual distribution can be represented as the sum of several Maxwellians, each with a separate temperature. Source Instrument Parameters ============================ Instrument Host ID : VG2 Data Set Parameter Name : ELECTRON DENSITY Instrument Parameter Name : ELECTRON RATE ELECTRON CURRENT Important Instrument Parameters : 1 (for both inst. parameters) Instrument Host ID : VG2 Data Set Parameter Name : ELECTRON TEMPERATURE Instrument Parameter Name : ELECTRON RATE ELECTRON CURRENT Important Instrument Parameters : 1 (for both inst. parameters) Processing ========== Processing History ------------------ Source Data Set ID : VG2-PLS Software : UNK Product Data Set ID : VG2-J-PLS-5-ELE-MOM-96.0SEC Data Coverage ============= Filename Records Start Stop ------------------------------------------------------------------- Volume ID: VG_1502 ELE_MOM.TAB 2278 1979-07-06T00:00:42.687Z 1979-07-09T23:59:06.436Z CONFIDENCE_LEVEL_NOTE Confidence Level Overview ========================= This data collection provides the best estimate available of the total electron density in the PLS energy range (10-5950 eV). Four assumptions were made 1) secondary electrons escaping from the collector plate of the detector were neglected; 2) extrapolations were made to estimate the number of electrons outside the PLS energy range; 3) electrons were assumed to have isotropic distributions; 4) where the spacecraft potential was small the shape of the thermal electron spectra was used to estimate the charge and correct the derived densities. 1) should result in an underestimate of the electron density by no more than 10% for T[e] < 100 eV and no more than 30% for T[e] > 100 eV. 2) gives uncertainties of at most 10%, and usually much smaller, for T[e] = 5-3000 eV which is the T[e] range measured in this region. 3) should be an excellent assumption since isotropization times for electrons are fast, and since the electron thermal speed is always much greater than the plasma flow speed. 4) in regions where the spacecraft charge is positive, charging produces uncertainties of at most 10%. Values of T[e] in all regions have uncertainties approximately equal to the density uncertainties. Missing Data Flag ================= Any column whose value is -9.99e+10 is a bad or missing data value.