Data Set Overview
  =================

    Version 1.1
    -----------
      This version 1.1 data set replaces the version 1.0 data set
      (DATA_SET_ID = VG1-J-PLS/PRA-5-ELE-MOM-96.0SEC) previously
      archived with the PDS.


    Data Set Description
    --------------------
      This data set contains derived values of the electron density
      and moment temperature at Jupiter during the Voyager 1
      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 [SCUDDERETAL1981].  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.  On day 64 from 415-1830 negative charging of the
      spacecraft renders electron moment densities unreliable.
      Therefore, the PLS ion densities were used to derive electron
      densities from 0415-1400 assuming charge neutrality and from
      1830-1940 using a model based on inbound plasma parameters.
      PRA densities were used to derive electron densities from
      1400 to 1830.  Electron temperatures derived from PLS
      electron data are used except inside L=5.4, where T[E] was
      set equal to T[I] and should be considered an upper limit.
      The data used from 415-1830 on day 64 are described in
      [SITTLER&STROBEL1987].  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.  Additional information about
      this data set and the instrument which produced it can be
      found elsewhere in this catalog.  An overview of the data in
      this data set can be found in [SCUDDERETAL1981] and
      [SITTLER&STROBEL1987] and a complete instrument description
      can be found in [BRIDGEETAL1977].

      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              : VG1
    Data Set Parameter Name         : ELECTRON DENSITY
    Instrument Parameter Name       : ELECTRON RATE
                                      ELECTRON CURRENT
    Important Instrument Parameters : 1 (for both inst. parameters)

    Instrument Host ID              : VG1
    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          : VG1-PLS
      Software                    : UNK
      Product Data Set ID         : VG1-J-PLS/PRA-5-ELE-MOM-96.0SEC


  Data Coverage
  =============

    Filename Records Start                     Stop
    -------------------------------------------------------------------
    T790301  5380    1979-03-01T12:27:43.435Z  1979-03-07T11:59:03.738Z

Confidence Level Overview
  =========================
    This data set 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 electron temperature (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 (outside 10 R[J]) charging
    produces uncertainties of at most 10%.  inside of ~10 R[J] the
    spacecraft potential is negative and electron densities are not
    reliable.  From 0415 to 1940 on March 5 the ion charge density
    was used to estimate the electron density using the condition
    of charge neutrality.  Uncertainties for the ion charge density
    in this region are less than 10%.  From 1400-1830 electron
    densities derived from PRA densities are used; these have
    uncertainties of at most 20%.  From 1830-1940 no direct
    measurement of electron density is available and 'predict
    densities' based on inbound ion measurements and a model of the
    plasma distribution are used.  T[E] in all regions except
    between 1000 and 1350 is calculated from the PLS electron data
    and has uncertainties approximately equal to the density
    uncertainties.  Between 1000 and 1350 T[E] is so far below the
    instrument threshold of 10 eV that no signal is seen; in this
    region te is set equal to the ion temperature observed at the
    same L shell and should be considered an upper limit.


  Missing Data Flag
  =================
    Any column whose value is -9.99e+10 is a bad or missing data
    value.