Data Set Information
DATA_SET_NAME VOYAGER 1 SATURN PLASMA DERIVED ION MOMENTS 96 SEC
DATA_SET_ID VG1-S-PLS-5-ION-MOM-96.0SEC
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview : THIS DATA SET CONTAINS ESTIMATES OF THE ION MOMENT DENSITY IN THE PLS VOLTAGE RANGE (10-5950 EV/Q) AT SATURN DURING THE VOYAGER 1 ENCOUNTER. RIGID COROTATION IS ASSUMED, WHICH LEADS TO AN UNDERESTIMATE OF THE DENSITY IN SOME REGIONS, AS DOES THE USE OF AN ACCEPTANCE AREA RELEVANT FOR A COLD BEAM FOR PLASMA WHICH IS TRANSONIC IS SOME REGIONS. DENSITIES MAY BE UNDERESTIMATED BY A FACTOR OF 2-3 IN THE INNER MAGNETOSPHERE, SO THIS DATA SET SHOULD BE USED PRIMARILY FOR STUDIES USING VARIATIONS IN PLASMA DENSITY. THE FIT DENSITIES GIVE A BETTER ESTIMATE OF THE ABSOLUTE DENSITY. THIS IS THE DATA SHOWN AND DESCRIBED IN DETAIL IN LAZARUS AND MCNUTT (1983). DATA FORMAT: COLUMNS 1-5 ARE TIME (YEAR, DAY, HOUR, MIN, SEC) AND COLUMN 6 IS THE MOMENT DENSITY IN CM-3. EACH ROW HAS FORMAT (I5,I4,2I3,I4,F8.3). VALUES OF 1.E32 INDICATE THAT THE PARAMETER COULD NOT BE OBTAINED FROM THE DATA USING THE STANDARD ANALYSIS TECHNIQUE. ADDITIONAL INFORMATION ABOUT THIS DATASET 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 LAZARUS AND MCNUTT (1983) AND A COMPLETE INSTRUMENT DESCRIPTION CAN BE FOUND IN BRIDGE (1977). Processing Level Id : 5 Software Flag : Y Parameters : Sampling Parameter Name : TIME Data Set Parameter Name : ION 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 Description ----------- 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 dataset. 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. 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 DENSITY Instrument Parameter Name : PARTICLE MULTIPLE PARAMETERS Important Instrument Parameters : 1 Processing : Processing History ------------------ Source Data Set ID : VG1-PLS Software : MOMANAL Product Data Set ID : VG1-S-PLS-5-ION-MOM-96.0SEC Software 'MOMANAL' ------------------ Software Name : MOMANAL Software Type : PIN Software Release Date : N/A Node ID : N/A Cognizant Engineer : N/A Software Access Description : N/A
DATA_SET_RELEASE_DATE 1988-08-01T00:00:00.000Z
START_TIME 1980-11-12T03:00:11.000Z
STOP_TIME 1980-11-13T08:58:35.000Z
MISSION_NAME VOYAGER
MISSION_START_DATE 1972-07-01T12:00:00.000Z
MISSION_STOP_DATE N/A (ongoing)
TARGET_NAME SATURN
TARGET_TYPE PLANET
INSTRUMENT_HOST_ID VG1
INSTRUMENT_NAME PLASMA SCIENCE EXPERIMENT
INSTRUMENT_ID PLS
INSTRUMENT_TYPE PLASMA ANALYZER
NODE_NAME Planetary Plasma Interactions
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE Overview : THIS DATA SET PROVIDES AN ESTIMATE OF THE POSITIVE ION CHARGE DENSITY. SEVERAL ASSUMPTION/SIMPLIFICATIONS ARE MADE TO SIMPLIFY THE ANALYSIS WHICH MAY AFFECT THE ACCURACY OF THE RESULTS. HIGH MACH NUMBER FLOW IS ASSUMED; MACH NUMBERS OF 1, WHICH ARE OBSERVED IN THE INNER MAGNETOSPHERE, CAN RESULT IN 50% UNDERESTIMATES OF THE CHARGE DENSITY. THE ANALYSIS ASSUMES A UNIT RESPONSE (IE., ALL PARTICLES IN A COLD BEAM INCIDENT ON THE APERTURE OF THE EXPERIMENT WOULD BE MEASURED AT THE COLLECTOR). THE ACTUAL RESPONSE IS AS LOW AS 70%. A VELOCITY INTO THE DETECTOR MUST ALSO BE ASSUMED; THE VELOCITY USED IS THE COROTATION VELOCITY. OBSERVATIONS INDICATE THAT IN SOME REGIONS THE ACTUAL VELOCITY IS AS LITTLE AS HALF OF THE COROTATION VELOCITY, GIVING FACTOR OF 2 ERRORS IN THE DENSITY. FINALLY, ONLY IONS IN THE PLS ENERGY RANGE (10-5950 EV/Q) ARE COUNTED. THE CUMULATIVE ERROR FROM ALL THESE EFFECTS IS LESS THAN 10% IN THE SOLAR WIND, LESS THAN A FACTOR OF 2 IN THE OUTER MAGNETOSPHERE (R>10 RS), AND UP TO A FACTOR OF 3 INSIDE THIS. SINCE THE AMPLITUDE OF EACH OF THESE EFFECTS VARIES SLOWLY IN TIME (DISTANCE), THE RELATIVE CHANGES IN DENSITY ARE GOOD TO 10 PERCENT IN MOST CASES. THIS DATA SET IS MOST USEFUL FOR LOOKING AT DENSITY VARIATIONS; ION FIT DENSITIES ARE MUCH BETTER INDICATORS OF THE ABSOLUTE PLASMA DENSITY
CITATION_DESCRIPTION Citation TBD
ABSTRACT_TEXT THIS DATA SET CONTAINS ESTIMATES OF THE ION MOMENT DENSITY IN THE PLS VOLTAGE RANGE (10-5950 EV/Q) AT SATURN DURING THE VOYAGER 1 ENCOUNTER. RIGID COROTATION IS ASSUMED, WHICH LEADS TO AN UNDERESTIMATE OF THE DENSITY IN SOME REGIONS, AS DOES THE USE OF AN ACCEPTANCE AREA RELEVANT FOR A COLD BEAM FOR PLASMA WHICH IS TRANSONIC IS SOME REGIONS. DENSITIES MAY BE UNDERESTIMATED BY A FACTOR OF 2-3 IN THE INNER MAGNETOSPHERE, SO THIS DATA SET SHOULD BE USED PRIMARILY FOR STUDIES USING VARIATIONS IN PLASMA DENSITY. THE FIT DENSITIES GIVE A BETTER ESTIMATE OF THE ABSOLUTE DENSITY. THIS IS THE DATA SHOWN AND DESCRIBED IN DETAIL IN LAZARUS AND MCNUTT (1983). DATA FORMAT: COLUMNS 1-5 ARE TIME (YEAR, DAY, HOUR, MIN, SEC) AND COLUMN 6 IS THE MOMENT DENSITY IN CM-3. EACH ROW HAS FORMAT (I5,I4,2I3,I4,F8.3). VALUES OF 1.E32 INDICATE THAT THE PARAMETER COULD NOT BE OBTAINED FROM THE DATA USING THE STANDARD ANALYSIS TECHNIQUE. ADDITIONAL INFORMATION ABOUT THIS DATASET 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 LAZARUS AND MCNUTT (1983) AND A COMPLETE INSTRUMENT DESCRIPTION CAN BE FOUND IN BRIDGE (1977).
PRODUCER_FULL_NAME JOHN D. RICHARDSON
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