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- The Solar Wind Plasma Experiment on Ulysses is accurately characterizing the
bulk flow and internal state conditions of the interplanetary plasma in three
dimensions on the way out to Jupiter. These observations will continue over the
full range of heliocentric distances and heliographic latitudes reached by the
probe after its encounter with Jupiter and consequent deflection out of the
ecliptic plane. Solar wind electrons and ions are measured simultaneously with
independent curved-plate electrostatic analyzers equipped with multiple Channel
Electron Multipliers (CEMs). The CEMs are arranged to detect particles at
chosen polar angles from the spacecraft spin axis; resolution in spacecraft
azimuth is obtained by timing measurements with the spacecraft Sun clock as the
spacecraft spins. Electrons with central energies extending from 0.86 eV to 814
eV are detected at seven polar angles and various combinations of azimuth angle
to cover the unit sphere comprehensively, so as to enable computation of the
pertinent electron velocity distribution parameters. As the average electron
flux level changes with heliocentric distance, command control of the CEM
counting intervals is used to extend the dynamic range. Ions are detected
between 255 eV/q and 34.4 keV/q using appropriate subsets of 16 CEMs at spin
angles designed to provide matrices of counts as a function of energy per
charge, azimuth angle, and polar angle centered on the average direction of
solar-wind flow. Data matrices are obtained every 4 min when the spacecraft is
actively transmitting and every 8 min during data store periods. These matrices
contain sufficient energy and angle resolution to permit a detailed
characterization of the ion velocity distributions from which ion bulk
parameters are derived. As the average ion flux intensity changes with
heliocentric distance, the entrance aperture size is periodically optimized by
command selection from a set of seven apertures on a disk driven by a stepping
motor. Changes in the average solar wind flow direction relative to the
Earth-pointing spacecraft spin axis are accommodated by command selection of
the proper measurement matrix from a set of 11 matrices. In a separate mode of
operation and under favorable conditions, heavy ions of oxygen, silicon, and
iron at various charge levels are resolved.
(Abstract from: S.J. Bame et al., Astron. Astrophys. Suppl. Ser. 92, 237-265,
1992)
For more information, see:
http://swoops.lanl.gov/
and
http://ulysses.jpl.nasa.gov/spacecraft/inst_swoops.html
Group: Instrument_Details
Entry_ID: SWOOPS
Group: Instrument_Identification
Instrument_Category: Solar/Space Observing Instruments
Instrument_Class: Particle Detectors
Short_Name: SWOOPS
Long_Name: Solar Wind Plasma Experiment (Ulysses)
End_Group
Group: Instrument_Associated_Sensors
Short_Name: EAE/SWOOPS
Short_Name: IAE/SWOOPS
End_Group
Group: Associated_Platforms
Short_Name: ULYSSES
End_Group
Group: Spectral_Frequency_Information
Wavelength_Keyword: X-Ray
Number_Channels: 7
Spectral_Frequency_Coverage_Range: 1 eV - 900 eV
End_Group
Group: Spectral_Frequency_Information
Wavelength_Keyword: Gamma Ray
Number_Channels: 16
Spectral_Frequency_Coverage_Range: 257 eV - 35 KeV
End_Group
Online_Resource: http://swoops.lanl.gov/index.html
Online_Resource: http://ulysses-ops.jpl.esa.int/ulysses/archive/swoops.html
Sample_Image: http://ulysses-ops.jpl.esa.int/ulysses/images/bai.gif
Group: Instrument_Logistics
Data_Rate: 100 kbps
Instrument_Start_Date: 1990-10-06
Instrument_Owner: Los Alamos National Laboratory
End_Group
End_Group
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