Magnetospheric Plasma Analyzer MPA Measurements from LANL Geosynchronous Satellites

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04-7323
Magnetospheric Plasma Analyzer (MPA) Measurements
From LANL Geosynchronous Satellites
Michelle F. Thomsen ISR-1 (Space Science and
Applications) Los Alamos National Laboratory
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Magnetospheric Plasma Analyzer (MPA) Measurements
fromLANL Geosynchronous Satellites

• Michelle F. Thomsen
• Los Alamos National Laboratory
• Los Alamos, NM

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Outline

• Instrument Description
• Representative Measurements
• Time Coverage, LT coverage
• Known Concerns
• Derived Parameters
• Inter-calibration
• Statistical Analyses
• Comparison with Polar data

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Los Alamos MPA

• 1 kg, 1 watt
• 60 electrostatic spherical section
• single set of curved plates, followed by 6
  Channel Electron Multipliers (CEM)
• different plate polarities and CEM bias for ions
  and electrons

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Each CEM views a different direction in space
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MPA Measurements
Energy per Charge Range 1.0 - 40,400 eV/e
(electrons) 1.1 - 43,600 eV/e (ions)Energy
Bins 40 (logarithmically spaced)Energy
Resolution ?E/E 0.40Azimuthal Bins
24Intrinsic Azimuthal Response 8,12,21Polar
Viewing 21-44, 44-67, 67-90, 90-113, 113-136,
136-159Accumulation Time per Bin 9 msecSpin
Period (Full Distn. Accum. Time) 10.1 secFull
3-D Distn. Repetition 86 sec (electrons)
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Representative Measurements LANL-02A
log energy (eV) -gt
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Time Coverage
Geosynchronous Satellite Locationsat 0 UT on 18
September 2002
LANL-02A
LANL-97A
1989-046 10/89 - 2/01 1990-095 2/91 -
present 1991-080 2/92 - present 1994-084 2/95 -
present LANL-97A 7/97 - present LANL-01A 2/01 -
present LANL-02A 2/02 - present
1994-084
LANL-01A
1991-080
(1989 -046)
1990-095
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Local Time Coverage
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Known Concerns

• Degradation of sweep high voltage power supply
  on first 3 satellites gt reduced maximum energy
• Failure of 1 CEM (of 6) on 5 satellites (2
  subsequently recovered) gt uncertainties in
  radial flows
• Intermittent failure of bias HV on 1989-046
  since 2000 gt intermittent loss of ion
  measurements
• Sporadically elevated background level on
  LANL-01A gt slightly noisier flux values

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Derived Parameters

• Full 3-D distribution functions
• Spin-averaged differential fluxes
• Moments (density, temperature, some flow
  velocities) for three species
• Hot electrons (gt30 eV)
• Hot ions (gt100 eV)
• Cold ions (lt100 eV)
• Spacecraft surface potential
• Also
• Magnetic field direction (from symmetry axis of
  distributions)
• Measure of strength of convection
• Possible composition information (see below)
• Spectral characterization (in progress)

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Example Densities
LANL-02A
2 July 2003
18 LT
UT
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Example Spacecraft Potential
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Example Magnetic Field Direction
LANL-02A
2 July 2003
UT
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Example Composition
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Example Composition
UT
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Inter-calibration
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Statistical Studiesplasma sheet, plasmasphere,
magnetopause, lobe
See especially H. Korth et al., J. Geophys.
Res., 1999. M. H. Denton et al., J. Geophys.
Res., submitted, 2004.
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Statistical Studies
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Statistical Studies
(need Php vs Dst)
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Solar Cycle StudiesExample Te
1990
(need solar cycle nhe montage)
2001
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Solar Cycle Studies O/H
1990
Kp -gt
2001
LT
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Storm Superposed Epoch Studies
M. H. Denton in collaboration with Jichun Zhang
and Mike Liemohn, Univ. of Michigan
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Storm Superposed Epoch
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Comparison with Polar
An Empirical Low-Energy Ion Model of the Inner
Magnetosphere, J. L. Roeder, M. W. Chen, J. F.
Fennell, and R. Friedel, Proceedings of the 8th
Spacecraft Charging Technology Conference, J. L.
Minor, ed., Huntsville, Alabama, October, 20-24,
2003.
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Summary Los Alamos MPA

• geosynchronous orbit
• 59 satellite-years of data
• more than one full solar cycle
• excellent LT coverage
• multiple simultaneous measurements
• ions and electrons, 1 eV to 45 keV
• 86-s temporal resolution
• full 3-dimensional measurements
• spin-averaged fluxes and moments readily
  available
• access to full 3-D distributions