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VG1 JUP PLS DERIVED ION IN/OUTBND MAGSHTH L-MODE 96SEC V1.0 (PDS)

NSSDCA ID: PSFP-00501

Availability: Archived at NSSDC, accessible from elsewhere

Time span: 1979-02-28 to 1979-03-24

Description

This description was generated automatically using input from the Planetary Data System.

Data Set Overview ================= Instrument P.I. : John D. Richardson Data Supplier : John D. Richardson Data sampling rate : 96 seconds Data Set Start Time : 1979-02-28T14:36:12.546Z Data Set Stop Time : 1979-03-24T23:19:32.241Z This data set contains plasma parameters from the Voyager 1 inbound magnetosheath and outbound data from the magnetotail through the solar wind. Inbound Voyager 1 passed near noon local time, so it sampled regions of the magnetosheath where flow is generally subsonic. Distribution functions observed were well represented by two convected isotropic proton Maxwellians, so this type of distribution was used to derive the proton velocity, density and temperature. Physically the two populations represent the thermal plasma accelerated at the shock (the colder component) and ions reflected once at the shock before entering the magnetosheath (the hotter component). The PLS experiment could not resolve alpha particles in this region so no alpha parameters are provided; the neglect of alpha made cause an overestimate of the hot proton component of the plasma. One sigma errors are provided for the fit parameters. The outbound data has fit and moment parameters; the fit parameters assume a single, isotropic convected proton Maxwellian distribution. Although magnetotail data is provided, these data are unreliable; the density can be used as an upper limit to the actual density. Solar wind data are also provided. However, we recommend using the M-mode data for the solar wind as the L mode data has lower energy resolution so the temperatures are too high and the non-radial velocity flows less accurate. The L mode data are the best data to use in low density regions of the magnetosheath, but in general the M-mode data are preferable and this data should be used only to increase time resolution over that provided by the M-mode data. Magnetotail and solar wind data in this data set are included mainly to put the sheath data in context and show magnetopause and shock locations. Parameters ========== Data Set Parameter 'ION DENSITY' -------------------------------Data Set Parameter Name : ION DENSITY Data Set Parameter Unit : CM**-3 Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : UNK Maximum Sampling Parameter : UNK Sampling Parameter Interval : UNK Minimum Available Sampling Int : UNK Noise Level : UNK A derived parameter equaling the number of ions per unit volume over a specified range of ion energy, energy/charge, or energy/nucleon. Discrimination with regard to mass and or charge state is necessary to obtain this quantity, however, mass and charge state are often assumed due to instrument limitations. Many different forms of ion density are derived. Some are distinguished by their composition (N+, proton, ion, etc.) or their method of derivation (Maxwellian fit, method of moments). In some cases, more than one type of density will be provided in a single data set. In general, if more than one ion species is analyzed, either by moment or fit, a total density will be provided which is the sum of the ion densities. If a plasma component does 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. Data Set Parameter 'ION THERMAL SPEED' -------------------------------------Data Set Parameter Name : ION THERMAL SPEED Data Set Parameter Unit : KM/S Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : UNK Maximum Sampling Parameter : UNK Sampling Parameter Interval : UNK Minimum Available Sampling Int : UNK Noise Level : UNK A measure of the velocity associated with the temperature of the ions. It is formally defined as the Ion Thermal Speed squared equals two times K (Boltzmann's constant) times T (temperature of ion) divided by M (ion mass). Each component of a plasma has a thermal speed associated with it. Data Set Parameter 'ION VELOCITY' --------------------------------Data Set Parameter Name : ION VELOCITY Data Set Parameter Unit : KM/S Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : UNK Maximum Sampling Parameter : UNK Sampling Parameter Interval : UNK Minimum Available Sampling Int : UNK Noise Level : UNK A derived parameter giving the average speed and direction of motion of a plasma or plasma component. The velocity can be obtained by taking the first moment of the distribution function or by simulating the observations with some known distribution function, usually a Maxwellian, to the distribution. Velocities are given in heliographic (RTN) coordinates: R is radially away from sun, T is in plane of sun's equator and positive in the direction of solar rotation, N completes right-handed system. Source Instrument Parameters ============================ Instrument Host ID : VG1 Data Set Parameter Name : ION DENSITY Instrument Parameter Name : ION RATE Important Instrument Parameters : 1 Instrument Host ID : VG1 Data Set Parameter Name : ION DENSITY Instrument Parameter Name : ION CURRENT Important Instrument Parameters : 1 Instrument Host ID : VG1 Data Set Parameter Name : ION VELOCITY Instrument Parameter Name : ION CURRENT Important Instrument Parameters : 1 Instrument Host ID : VG1 Data Set Parameter Name : ION THERMAL SPEED Instrument Parameter Name : ION RATE Important Instrument Parameters : 1 Instrument Host ID : VG1 Data Set Parameter Name : ION THERMAL SPEED Instrument Parameter Name : ION CURRENT Important Instrument Parameters : 1 Instrument Host ID : VG1 Data Set Parameter Name : ION DENSITY Instrument Parameter Name : PARTICLE MULTIPLE PARAMETERS Important Instrument Parameters : 1 Data Coverage ============= Filename Records Start Stop ------------------------------------------------------------------T79059 914 1979-02-28T14:36:12.546Z 1979-03-03T02:20:12.781Z T79072 10012 1979-03-13T00:02:44.136Z 1979-03-24T23:19:32.241Z

These data are available on-line from the Planetary Data System (PDS) at:

https://pds-ppi.igpp.ucla.edu/data/VG1-J-PLS-5-SUMM-ION-L-MODE-96S-V1.0/

Alternate Names

  • VG1-J-PLS-5-SUMM-ION-L-MODE-96S-V1.0

Discipline

  • Planetary Science: Fields and Particles

Additional Information

Spacecraft

Questions and comments about this data collection can be directed to: Dr. Edwin V. Bell, II

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. John D. RichardsonGeneral ContactMassachusetts Institute of Technologyjdr@space.mit.edu
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