SLIDE 1
CLUSTER & IMAGE:
Preliminary comparison between ion distribution functions measured by CLUSTER-CIS in the inner magnetosphere and ion distributions obtained from IMAGE-HENA energetic neutral atom image inversions
Iannis Dandouras (1), Claire Vallat (1), Pontus C:son Brandt (2), Donald G. Mitchell (2), Edmond C. Roelof (2), Malcolm Dunlop (3), Henri Rème (1), André Balogh (3)
(1) Centre d'Etude Spatiale des Rayonnements, Toulouse, France (2) Applied Physics Laboratory, Johns Hopkins University, Maryland, USA (3) Blackett Laboratory, Imperial College, London, UK
Yosemite Magnetospheric Imaging Workshop, Feb. 2002
SLIDE 2 Orbit
Magnetopause Bow shock Plasmasphere Solar wind
Regions visited by Cluster
- High eccentricity, high inclination orbit : several plasma domains analyzed.
- Tetrahedric configuration : temporal and spatial decorrelation.
- Adaptive geometry of the tetrahedron: according to the plasma cell scales.
SLIDE 3 IMAGE CLUSTER
FOV
SLIDE 4
CIS : The Instrument
SLIDE 5
Solar wind Magnetosheath
CIS Dynamic Range
Lobe
SLIDE 6 CODIF: Ion Composition and Distribution Function Analyser
TOF system
2
2 × = TOF L q E q m
L
q E
Main entrance RPA entrance :
≈ 0 eV ≤ ERPA ≤ 25 eV
SLIDE 7
Main features and measured parameters of the CIS experiment
SLIDE 8
CIS – HENA: EVENTS
SLIDE 9 Dst = -28 nT Dst = 6 nT
SLIDE 11
HENA: ring current with some enhancement around dusk CIS: near the inner edge of the ring current
SLIDE 12 For α ≈ 90° ions (27 keV < E < 39 keV) :
From HENA inversions: fi ≈ 6×105 cm-2s-1sr-1keV-1 Measured in situ by CIS: fi ≈ 8.5×104 cm-2s-1sr-1keV-1
SLIDE 13
SLIDE 14
HENA: recovery ring current CIS: near the outer edge of the ring current; substantial O+ content
SLIDE 15 For α ≈ 90° ions (27 keV < E < 39 keV) :
From HENA inversions: fi ≈ 1×105 cm-2s-1sr-1keV-1 Measured in situ by CIS: fi ≈ 3.5×104 cm-2s-1sr-1keV-1
SLIDE 16
SLIDE 17
HENA: narrow substorm injection on the nightside; low counting statistics elsewhere CIS: low, equatorially gyrating ion fluxes ⇓ Ions not generating ENAs in the HENA FOV
SLIDE 18 For α ≈ 90° ions (27 keV < E < 39 keV) :
From HENA inversions: fi ≈ 2×104 cm-2s-1sr-1keV-1 Measured in situ by CIS: fi ≈ 4.3×104 cm-2s-1sr-1keV-1 CAUTION: low counting statistics
SLIDE 19 CIS – HENA Ion Flux Comparison
1.0E+02 1.0E+03 1.0E+04 1.0E+05 1.0E+06 4/12/01 5/12/01 6/12/01 7/12/01 Event date Ion Flux (27 - 39 keV) CIS 90° ion flux HENA inv. 90° ion flux
Note : Preliminary calibration values for CIS and for HENA (each by a factor of 2 – 3)
SLIDE 20 CONCLUSIONS
- First comparisons between ion fluxes obtained by HENA energetic neutral atom
image inversions and ion fluxes measured in situ by CIS.
- Preliminary results show the obtained and measured ion fluxes being very consistent.
- Complementarity of the two approaches:
- ENA images allow to put local measurements into a global context.
- Local measurements provide the full distribution function and give the “ground
truth” for a given pixel of an ENA image.
- Ion distribution functions show a variety of structures (equatorially gyrating ions,
fine-structured energy bands, etc.) .
- Coming soon :
- Analysis of ENA image time series: latitude profile and ion dynamics.
- ENA image inversions to obtain full pitch-angle distributions.
- Comparison with the ring current density obtained with the curlometer
technique (FGM ).
- Analysis of higher energy ion measurements (RAPID).
