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ACE Solar Wind Electron, Proton and Alpha Monitor (SWEPAM)

ResourceID
spase://SMWG/Instrument/ACE/SWEPAM

Description

The Solar Wind Electron, Proton, and Alpha Monitor (SWEPAM) instrument sensors measure solar wind electrons at 1 - 900 eV energy and ions at 0.26 - 35 keV. The instrument consists of separate electron and ion analyzers originally built as spares for the Ulysses mission. The two sensors both utilizes curved-plate electrostatic analyzers (ESAs) consisting of spherical sections cut into sectors. Biased channel electron multipliers (CEMS) are spaced along the exit apertures of the ESAs for ion and electron detection. Different CEMs sample different portions of the fan-shaped fields of view. The ion sensor consists of a 105-degree bending angle ESA with an average radius of 100 mm and a plate spacing of 2.84 mm. Sixteen CEMs contiguously spaced along the exit gap of the ESA give about 5-degree polar angular resolution over the approximately 70-degree opening angle of the acceptance fan. The electron sensor consists of a 120-degree bending angle ESA with an average radius of 41.9 mm and a plate spacing of 3.5 mm. Seven large-funnel CEMs along the exit gap give about 20-degree angular resolution over a 160-degree fan angle. The sensor geometric factors are 0.002 cm2-sr for isotropic response and 0.009 cm2 for unidirectional. Energy resolution is five percent for ions and twelve percent for electrons. SWEPAM data consists of ion and electron rates collected at each energy/charge (E/Q) step, polar lock direction, and azimuthal spin direction. A single spacecraft spin period of 12 seconds is sufficient for accumulation of count matricies to fully calculate the electron and ion distribution functions from which bulk moments (solar wind speed, density, temperature) can be calculated by ground data processing. Accumulated counts will actually be summed over one-minute intervals for increased statistical accuracy and for reduction of telemetry requirements. Limited data from single spins will be provided for timing of the passage of transient solar wind structures.

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Details

Version:2.0.1

Instrument

ResourceID
spase://SMWG/Instrument/ACE/SWEPAM
ResourceHeader
ResourceName
ACE Solar Wind Electron, Proton and Alpha Monitor (SWEPAM)
AlternateName
ACE SWEPAM
ReleaseDate
2019-05-05 12:34:56Z
Description

The Solar Wind Electron, Proton, and Alpha Monitor (SWEPAM) instrument sensors measure solar wind electrons at 1 - 900 eV energy and ions at 0.26 - 35 keV. The instrument consists of separate electron and ion analyzers originally built as spares for the Ulysses mission. The two sensors both utilizes curved-plate electrostatic analyzers (ESAs) consisting of spherical sections cut into sectors. Biased channel electron multipliers (CEMS) are spaced along the exit apertures of the ESAs for ion and electron detection. Different CEMs sample different portions of the fan-shaped fields of view. The ion sensor consists of a 105-degree bending angle ESA with an average radius of 100 mm and a plate spacing of 2.84 mm. Sixteen CEMs contiguously spaced along the exit gap of the ESA give about 5-degree polar angular resolution over the approximately 70-degree opening angle of the acceptance fan. The electron sensor consists of a 120-degree bending angle ESA with an average radius of 41.9 mm and a plate spacing of 3.5 mm. Seven large-funnel CEMs along the exit gap give about 20-degree angular resolution over a 160-degree fan angle. The sensor geometric factors are 0.002 cm2-sr for isotropic response and 0.009 cm2 for unidirectional. Energy resolution is five percent for ions and twelve percent for electrons. SWEPAM data consists of ion and electron rates collected at each energy/charge (E/Q) step, polar lock direction, and azimuthal spin direction. A single spacecraft spin period of 12 seconds is sufficient for accumulation of count matricies to fully calculate the electron and ion distribution functions from which bulk moments (solar wind speed, density, temperature) can be calculated by ground data processing. Accumulated counts will actually be summed over one-minute intervals for increased statistical accuracy and for reduction of telemetry requirements. Limited data from single spins will be provided for timing of the passage of transient solar wind structures.

Contacts
RolePerson
1.CoInvestigatorspase://SMWG/Person/David.J.McComas
2.TechnicalContactspase://SMWG/Person/Ruth.Skoug
InformationURL
Name
SWEPAM home page at LANL
URL
https://swepam.lanl.gov/
Description

Information about the SWEPAM instrument, with links to data and other documentation

InformationURL
Name
NSSDC's Master Catalog
URL
https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1997-045A-07
Description

Information about the Solar Wind Electron, Proton and Alpha Monitor (SWEPAM) experiment on the ACE mission.

InformationURL
Name
Space Science Reviews Journal Article
URL
https://link.springer.com/chapter/10.1007/978-94-011-4762-0_20
Description

Detailed information about the Solar Wind Electron, Proton, and Alpha Monitor (SWEPAM) instrument on the ACE mission.

PriorIDs
spase://SMWG/instrument/1997-045A-07
InstrumentType
ElectrostaticAnalyser
InvestigationName
Solar Wind Electron, Proton and Alpha Monitor (SWEPAM) on ACE
ObservatoryID
spase://SMWG/Observatory/ACE