<?xml version="1.0" encoding="UTF-8"?>
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    <Version>2.2.6</Version>
    <NumericalData>
        <ResourceID>spase://CDPP/NumericalData/AMDA/Rosetta/LAP/ros-lap-efl</ResourceID>
        <ResourceHeader>
            <ResourceName>e-field component (EFL)</ResourceName>
            <AlternateName>Electric field component, calculated on ground by
taking the difference between floating probe measurements on both probes and

dividing by distance</AlternateName>

            <ReleaseDate>2016-10-15T14:08:29Z</ReleaseDate>
            <Description>
The two LAP probes could be used to measure the component of the electric field along their 
separation vector, by measuring the voltage of them, taking the difference and dividing by the 
separation distance (5.0 m). Each probe could be fed by a bias current as is typically done on 
electric field instruments in tenuous plasmas, or be disconnected from the bias circuitry to 

ensure a good zero bias current (floating probes) as is typically done on sounding rockets.  

Bias currents were used in the early part of the mission, but when the comet ionosphere 

developed, the floating mode was found to give much more consistent data. Only data from 

the floating mode have been used for providing E-field data, and only when both probes are 
sunlit.

Positive value refers to electric field  pointing in the direction from probe 1 to probe 2.
 

The booms are not equal in length (2.24 and 1.62 m) and mounted on a big spacecraft (solar 
panel wingspan 32 m), so one cannot expect LAP to provide a useful DC electric field estimate. 
A moving average of the E-field over 32 s is therefore subtracted from the data in the EFL files. 

The effective bandwidth of the data therefore is about 0.03 Hz to 20 Hz, the upper 
limit set by the analog anti-aliasing filters. Note that the filtering may distort the lowest 

frequencies. 

There are no external comparison data for assessing the absolute accuracy of the LAP E-field 
measurements. The data themselves look very clean and well behaved [Karlsson et al., 2017; 
André et al, 2017], with very little of common mode signal remaining, despite the s/c poten tial 
being both high and highly variable. The technique with floating probes is proven on numerous 
sounding rockets in the terrestrial ionosphere [Maynard, 1998].
</Description>
            <Contact>       
                <PersonID>spase://CDPP/Person/Anders.Eriksson</PersonID>
                <Role>PrincipalInvestigator</Role>
            </Contact>
            <Contact>       
                <PersonID>spase://CDPP/Person/Erik.Johansson</PersonID>
                <Role>DataProducer</Role>
            </Contact>
            <InformationURL>
                <Name>RPC LAP User Guide</Name>
                <URL>http://amda.irap.omp.eu/help/parameters/RO-IRFU-LAP-UG.PDF</URL>
            </InformationURL> 
            <InformationURL>
                <Name>ROSETTA RPC-LAP to Planetary Science Archive Interface Control Document</Name>
                <URL>http://amda.irap.omp.eu/help/parameters/RO-IRFU-LAP-EAICD_2_0_1_PDF_A.PDF</URL>
            </InformationURL>
        </ResourceHeader>
        <AccessInformation>
            <RepositoryID>spase://SMWG/Repository/CDPP/AMDA</RepositoryID>
            <Availability>Online</Availability>
            <AccessRights>Restricted</AccessRights>
            <AccessURL>
                <URL>http://amda.cdpp.eu</URL>
            </AccessURL>
            <Format>NetCDF</Format>
        </AccessInformation>
        <ProviderName>PSA</ProviderName>  
        <ProviderResourceName>RO-C-RPCLAP-5-xxx-DERIV2-V1.0</ProviderResourceName>
        <InstrumentID>spase://CDPP/Instrument/AMDA/Rosetta/LAP</InstrumentID>
        <MeasurementType>ThermalPlasma</MeasurementType>
        <TemporalDescription>
            <TimeSpan>
                <StartDate>2014-03-24T08:12:59Z</StartDate>
                <StopDate>2016-09-30T10:31:16Z</StopDate>
            </TimeSpan>
            <Cadence_Min>PT0.05S</Cadence_Min>
            <Cadence_Max>PT35S</Cadence_Max>
        </TemporalDescription>
        <Parameter>
            <Name>e-field comp</Name>
            <ParameterKey>ros_lap_efl</ParameterKey>
            <Description>Electric field component, calculated on ground by 
                taking the difference between floating probe measurements on both probes and 
                dividing by distance, (V_P2-V_P1)/L. Positive value refers to electric field 
                pointing in the direction from probe 1 to probe 2.</Description>
            <Ucd/>
            <Units>mV/m</Units>
            <RenderingHints>
                <DisplayType>TimeSeries</DisplayType>
            </RenderingHints>
            <FillValue>-1.e+09</FillValue>
        </Parameter>        
        <Parameter>
            <Name>sampling conf</Name>
            <ParameterKey>ros_lap_efl_s</ParameterKey>
            <Description>Number that describes the exact combination of onboard 
s/w averaging and downsampling. The exact values are pointers into a table 
that describes both the number of samples that are averaged over and the 
downsampling rate</Description>
            <Ucd/>
            <Units/>         
            <RenderingHints>
                <DisplayType>TimeSeries</DisplayType>
            </RenderingHints> 
        </Parameter>
        <Parameter>
            <Name>quality flag</Name>
            <ParameterKey>ros_lap_efl_f</ParameterKey>
            <Description>Quality flag constructed as the sum of multiple terms, 
depending on what quality related effects are present. Each digit is either in 
the range 0 (best) to 7 (worst), or 9 (not used).</Description>
            <Ucd/>
            <Units/>         
            <RenderingHints>
                <DisplayType>TimeSeries</DisplayType>
            </RenderingHints> 
        </Parameter>            
     </NumericalData>
</Spase>