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.
|