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NumericalData

ResourceID
spase://ESA/NumericalData/Cluster-Rumba/ASPOC/PrimeParameter/PT4S
ResourceHeader
ResourceName
Cluster-Rumba Prime Parameter Active Spacecraft Potential Control (ASPOC) Data
AlternateName
Cluster II Rumba Prime Parameter ASPOC data
ReleaseDate
2021-04-27 17:52:14Z
Description

The ASPOC instrument is a single unit consisting of an electronics box and two cylindrical ion emitter modules. The emitters produce indium ions at approximately 6 KeV, in a current of less than 50 microamps. This is done by field evaporation of indium in the apex field of a needle. In the basic feedback mode of operation, a measurement of the spacecraft potential is supplied to the instrument from either the electric field experiment (EFW) or the electron analyzer (PEACE). This information is then used to adjust the emission current to reduce the spacecraft potential to some predetermined value. By default, priority is given to the EFW data, because of the higher resolution (0.034 V vs. ~1.4 V) and the more straightforward way in which the potential is derived. A calibration mode will measure the current voltage characteristics of the spacecraft, at the beginning of the mission and occasionally later to account for changes in the photoemission properties of the surface. This measurement is carried out by sweeping the ion emission current in incremental steps over some convenient range, allowing simultaneous measurements of the spacecraft potential. The length of each step is 2 to 4 spin periods. In addition to providing an improved environment for other experiments, ASPOC will permit scientific investigations of the photoelectric characteristics of the dependence of the spacecraft potential on plasma parameters, and of spacecraft charging in different plasma environments to be carried out in the so called active mode. For more details of the Cluster mission, the spacecraft, and its instruments, see the report 'Cluster: mission, payload and supporting activities,' March 1993, ESA SP 1159, and the included article 'Active Spacecraft Potential Control: an ion emitter experiment for Cluster,' by W. Riedler et al., from which this information was obtained.

Acknowledgement
NASA, Willi W. Riedler
Contacts
RolePersonStartDateStopDateNote
1.PrincipalInvestigatorspase://SMWG/Person/Willi.W.Riedler
2.CoInvestigatorspase://SMWG/Person/Arne.Pedersen
3.CoInvestigatorspase://SMWG/Person/Jan.Troim
4.CoInvestigatorspase://SMWG/Person/Rejean.J.L.Grard
5.CoInvestigatorspase://SMWG/Person/Roy.B.Torbert
6.CoInvestigatorspase://SMWG/Person/B.Narheim
7.CoInvestigatorspase://SMWG/Person/Richard.C.Olsen
8.CoInvestigatorspase://SMWG/Person/Rudolf.J.Schmidt
9.CoInvestigatorspase://SMWG/Person/Klaus.M.Torkar
10.MetadataContactspase://SMWG/Person/James.M.Weygand
InformationURL
Name
NSSDC's Master Catalog on the Active Spacecraft Potential Control (ASPOC)
URL
Description

Introduction to the Active Spacecraft Potential Control (ASPOC) on Cluster II Rumba

Association
AssociationID
AssociationType
ObservedBy
PriorIDs
spase://VMO/NumericalData/Cluster2-Rumba/ASPOC/PrimeParameter/PT4S
spase://VMO/NumericalData/Cluster-Rumba/ASPOC/PrimeParameter/PT4S
spase://VSPO/NumericalData/Cluster-Rumba/ASPOC/PrimeParameter/PT4S
AccessInformation
RepositoryID
Availability
Online
AccessRights
Open
AccessURL
Name
FTPS from SPDF (not with most browsers)
URL
Description

Prime Parameter Active Spacecraft Potential Control (ASPOC) data on Cluster II Rumba

AccessURL
Name
HTTPS from SPDF
URL
Description

In CDF via HTTP from SPDF

AccessURL
Format
CDF
Acknowledgement
NASA, Willi W. Riedler
AccessInformation
RepositoryID
Availability
Online
AccessRights
Open
AccessURL
Name
CDAWeb HAPI Server
URL
Style
HAPI
ProductKey
C1_PP_ASP
Description

Web Service to this product using the HAPI interface.

Format
CSV
Acknowledgement
NASA, Willi W. Riedler
ProcessingLevel
Calibrated
ProviderResourceName
Cluster II Rumba Prime Parameter Active Spacecraft Potential Control (ASPOC) Data
ProviderProcessingLevel
Calibrated
ProviderVersion
1
InstrumentIDs
MeasurementType
ElectricField
TemporalDescription
TimeSpan
StartDate
2001-01-30 00:00:00
RelativeStopDate
-P3M
Note
Time format in data files is: day, month, year hour, min, seconds. Ex: '01-Jan-1981 00:00:00.000'
Cadence
PT4S
ObservedRegion
Earth.Magnetosheath
ObservedRegion
Earth.Magnetosphere
ObservedRegion
Earth.Magnetosphere.Magnetotail
ObservedRegion
Earth.Magnetosphere.Main
ObservedRegion
Earth.Magnetosphere.Polar
ObservedRegion
Earth.Magnetosphere.RadiationBelt
ObservedRegion
Earth.NearSurface.AuroralRegion
ObservedRegion
Earth.NearSurface.Ionosphere
ObservedRegion
Earth.NearSurface.Plasmasphere
ObservedRegion
Earth.NearSurface.PolarCap
ObservedRegion
Heliosphere.NearEarth
Keywords
4 second
magnetosphere
auroral region
polar cap
cusp
bow shock
solar wind
magnetosheath
cluster
magnetotail
lobe
Parameter #1
Name
Half Width of Averaging Interval
ParameterKey
Half_interval__C1_PP_ASP
Description

Half width of averaging interval

Cadence
PT4S
Units
ms
UnitsConversion
1.0e-3>s
FillValue
-1.0000e+31
Support
SupportQuantity
Other
Parameter #2
Name
Universal Time
ParameterKey
Epoch__C1_PP_ASP
Description

Universal Time in data cell: day, month, year hour, min, seconds. Ex: '01-Jan-1981 00:00:00.000'.

Caveats
Interval centered time tag
Cadence
PT4S
Units
ms
UnitsConversion
1.0e-3>s
RenderingHints
AxisLabel
Epoch
FillValue
-1.0000e+31
Support
SupportQuantity
Temporal
Parameter #3
Name
Active Spacecraft Potential Control (ASPOC) Status
ParameterKey
Status__C1_PP_ASP
Description

Cluster II Rumba prime parameter active spacecraft potential control status at spin time resolution

Cadence
PT4S
ValidMin
0
ValidMax
255
FillValue
255
Support
SupportQuantity
Other
Parameter #4
Name
Active Spacecraft Potential Control (ASPOC) Ion Current Data
ParameterKey
I_ion__C1_PP_ASP
Description

Cluster II Rumba prime parameter active spacecraft potential control ion current data at spin time resolution

Cadence
PT4S
Units
uA
UnitsConversion
1.0e-6>A
RenderingHints
AxisLabel
I_ion
ScaleMin
0
ScaleMax
50
ValidMin
0
ValidMax
50
FillValue
-1.0000e+31
Field
Qualifier
Total
FieldQuantity
Current