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 2 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 IN 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 ARE DESCRIBED AS BELOW: : name type description --------------------------------------------------- time A24 Output from Time fitting pro_den 1PE9.2 proton density (1/cm^-3) pro_temp 1PE9.2 proton temperature  hion_den 1PE9.2 heavy ion density  hiontemp 1PE9.2 heavy ion temperature  v_rho 1PE9.2 velocity Rho component  v_phi 1PE9.2 velocity Phi component  v_z 1PE9.2 velocity Z component  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 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. Source Instrument Parameters : Instrument Host ID : VG2 Data Set Parameter Name : ION DENSITY Instrument Parameter Name : ION RATE Important Instrument Parameters : 1 Instrument Host ID : VG2 Data Set Parameter Name : ION DENSITY Instrument Parameter Name : ION CURRENT Important Instrument Parameters : 1 Instrument Host ID : VG2 Data Set Parameter Name : ION DENSITY Instrument Parameter Name : PARTICLE MULTIPLE PARAMETERS Important Instrument Parameters : 1 Processing : Processing History ------------------ Source Data Set ID : VG2-PLS Software : MOMANAL Product Data Set ID : VG2-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 Product Data Set ID : VG2-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

Confidence Level: : 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 30% 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. Data Coverage : Filename Records Start Stop --------------------------------------------------------------------- Volume ID: VG_1601 ION_BR.TAB 104 1981-08-25T07:21:12.002Z 1981-08-26T01:33:59.937Z Missing Data Flag : Any data column whose value is -9.99e+10 is a missing data value.