Prsentation PowerPoint

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Some objectives of a new exploration of Jovian
magnetosphere
Philippe Louarn CESR Toulouse
A tour of the jovian magnetosphere

• The Jovian system a unique environment for the
  study of general magneto-plasma processes
• The structure and the dynamic of a strongly
  magnetized system in fast rotation.
• The fast rotator theme
• 2) The magnetic/plasma interaction between a
  central body and satellites (Io, Europe,
  Ganymede)
• The binary system theme

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1) the fast rotator theme.

• A huge magnetized system in rotation
• - Tspin9.9 h
• Magnetic moment 600 Earths one
• (not very different from a pulsar !)
• Bsurf 430 µT
• - Distance of subsolar point 30 Rj
• (50 times Earths case)

A magnetosphere completely dominated by
rotation Distance of stagnation point (Wp
B0Rp3/Econv)1/2 with Econv 0.1 VSW EIMF larger
than distance of subsolar point.
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• Important effects of the rotation
• Structure of the magnetosphere
• The rotation deforms the magnetic field and leads
  to a concentration of plasma near the equatorial
  plane.
• 2) Transport of matter Role of the centrifugal
  forces -gt A kind of gravitation. May
  destabilize interchange modes.

Magnetodisc
Magnetodisc
g
From unstable to stable situation
g
dense
ligth
ligth
dense
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• The theme of plasma transport is central.
• - Internal magnetosphere (Rlt10 Rj). Region in
  rigid rotation and highly magnetized (b ltlt1).
  Diffusion by waves, small scale interchange
  (Bolton et al, Kivelson et al, Southwood and
  Kivelson, Ferrière and André)
• - Middle magnetosphere (10 Rjlt Rlt 30Rj)
  Breakdown of co-rotation -gtThe lag behind
  co-rotation progressively increases. (Hill, Mauk
  et al). A region that presents some
  characteristics of thin current sheets -gt Large
  scale instabilities and energetic processes The
  equivalent of substorms ? (Woch et al, Krupp et
  al, Louarn et al). Is the transport organized by
  global scale instabilities ?

Waves?
Io
Interchange?
Instability
Transport
Energy transfered to internal magnetosphere
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• External magnetosphere (Rgt50 Rj). How are
  particles lost.
• Not very well known. How the rotation stops ?
  Is there a planetary wind ?
• How is made the connection between the internal
  and external magnetosphere ?

Possible reconnection region.(Proposed by
Vasyliunas)
The recirculation problem The outward plasma
transport likely implies an outward magnetic flux
transport. How is the B-flux transported back to
internal magnetosphere ?
The high energy population Intense radiation
belt. How does Jupiter act as a giant particle
accelerator ? (outward transport of low energy
plasma/ inward injection of high energy
particles)
Synchrotron emission (Bolton et al)
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2) The binary system theme

• A system with prolific internal plasma sources
• -Ios volcanism 1 ton/s (Sulfur)
• -gtFormation of plasmas torus.
• Sputtering from icy satellites.
• Ganymede a satellite with a mini magnetosphere
• The produced plasma is initially not in
  corotation.
• -gt Source of stress in the magnetosphere.
• -gt Specific interactions with Jupiter. Visible
  as specific auroral spots

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The theme of interactions is central. Local
plasma/satellite interactions The plasma source
problem. - What are the different sputtering
processes ? What are their efficiency
(interaction with exospheres, with icy surfaces
) ? - Effects of the variations of Ios
volcanism on the torus ? - How plasma impact
modify the surface properties of icy satellite
(composition) ? Global plasma/satellite
magneto-plasma interaction A very specific form
of input of energy and momentum in the
magnetospheric system.
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• A complex non stationnary interaction.
• Alfven wave coupling
• Localized current systems and electrostatic
  structures. -gt Similar to Earth auroral physics
  but with a nicely constrained energy input

Jupiters ionosphere
System of alfven wave reflection
E
Io Torus
Intense turbulence
Radio Emissions (AKR like)
Downward current
Analogy with Earth auroral current regions
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Implication for the mission and the payload
(1). theme of interaction - What are the
different sputtering processes ? What are their
efficiency ? - What are the effects of the
variations of the Ios volcanism on the torus ?
- How plasma impacts modify the surface
properties of icy satellite ? Measurements near
moons. Low energy ion composition, neutrals and
energetic particles are fundamental. - How is
the current system between moons and jupiter
established ? What is its nature ? What is its
efficiency in terms of global angular momentum
transport ? - What is the power transmitted by
Alfven waves ? On what spatial scales ? - How
is this power related to the brightness of the
aurora ? Importance of wave analysis. B and E
antenna.
High time resolution is the main point. Good wave
determination (Poynting flux) is fundamental .
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Implication for the mission and the payload
(2). theme of transport - How newborn ions
created at Io and Europe fill the plasma torus
? - What are the small scale transport processes
that determine the structure of torus ?
Measurements near moons, with low energy ion
composition and waves measurements.Neutrals and
energetic particles are also very important..
- How the torus is connected to the magnetodisc
? - What is the dynamics of the magnetodisc ?
Stable ? Unstable ? At which scales ? With what
processes? What are their roles in the plasma
transport ? - How are the particles lost far
from Jupiter ? Is there a planetary wind ?
Fundamental importance of 2 points
measurements with a complete plasma suite.Remote
analysis of the activity using radio emissions
E-antenna. Survey of auroral processes would be a
plus Good composition measurements and
complete energy coverage are fundamental. B is
also fundamental.
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The ideal 3 components of a new exploration.
3- The Jupiter/satellite and Jupiter/magnetodisc
Coupling. Auroral Processes. Jovian polar orbiter
2-Investigation of disc dynamics and large scale
transport Jovian equatorial orbiter
1- The local view of satellite interaction and
plasma transport Satellite orbiter
Nice, but means a GOOD magnetospheric payload
10 W, 10 kg are absolute minimum
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MAGNETOSPHERIC PAYLOAD B- field 2 kg
1 W (with boom, 2m ) E-field 2
kg 1 W (single short antenna,gt
3m) Energetic particules 1 kg 1
W (radiation monitor) (10x10x10) Ion
Composition 3 kg 4 W (20x20x30) Electrons
1 kg 1W (10x10x15) Neutrals 1.5
kg 2 W (15x15x15) Dust 1.5
kg 2 W (15x15x15) 9 kg 12 kg 8 W
11 W