ARTEMIS Science Working Team Meeting 9/14-16/2011

LUNAR PRECURSOR EFFECTS IN THE TERRESTRIAL MAGNETOSPHERE AND SOLAR WINDJasper S. HalekasSpace Sciences LaboratoryUniversity of California, Berkeley

The Lunar Space Plasma Environment: Pre-ARTEMIS

Precursor Effects in the Terrestrial Magnetosphere

All Electrons

Upgoing e- (0-15°)

Downgoing e- (165-180°)

EFI FFT

SCM FFT

B Wavelets

B Field

fpfce

fci

fpfce

Spin Tone

EFI Background

Free Energy Sources: Reflected Electrons in Magnetosphere

Loss Cone

Beam

Beam + Loss Cone:Produced By CombinedMagnetic & ElectrostaticEffects Near Surface

DownwardElectric Field

Plasma Electrons Follow Magnetic Field Linesand Reflect from E & B

Secondary ElectronsAccelerated Upward

E = - U

Δ

Converging Magnetic Field Lines above Crustal Magnetic Fields

Polarization Properties

Coherent

Parallel-Propagating

Right-Handed

• Wave properties all consistent with parallel-propagating whistlers coming down the magnetic field line towards the Moon

NarrowbandWaves propagating anti-parallel to field

EXB

EB

B0

Instability Conditions

EFI

SCW

Reduced DistributionFunctionWhistler Mode: ω/k, (ωce-ω)/k

Streaming instabilities where df/dv|| positive

Whistlers correlate with edges of loss cone: i.e. df/dvperp positive

Ions in the Mix?• Waves near fci modulate both the electron beam and the whistlers• Possible sources: Electron beam, shadowed ion distributions, bi-ion streaming

FGM Wavelets

Loss Cone Modulated

Electron Beam Modulated

Whistlers ModulatedProton & HeliumCyclotron Frequencies

ICWs?

Precursor Effects in the Solar Wind

IonsUpgoing e- (0-15°)

Downgoing e- (165-180°)

EFI FFT

SCM FFT

B Wavelets

B Field

SZA of SurfaceConnection

Fitzenreiter et al., 1990

Solar

Wind

Free Energy Sources: Reflected Electrons in Solar Wind

Generalized obstacle with magnetic fieldgradient and/or electrostatic potential gradient

MagneticField

ConvectionElectric Field

Electron Trajectory

Adiabatic Reflection in dHT Frame Gives you “Ears” in Solar Wind Frame

Whistler Cyclotron Resonance Conditions

EFI

SCW

Reduced DistributionFunction

(ωce-ω)/k : ω, k on whistler branch

Ion Observations

P2 Ions

P1 Ions

P1 Reduced Dist. Funct.

P1 Power Spectrum

P1 Propagation

P1 Ellipticity

Parallel-Propagating

RH, LH

Foreshock Ions

Reflected Protons

Free Energy Sources: Reflection From Crustal Magnetic Fields

Reflected Proton FluxesLue et al., 2010

Reflected ProtonsFollow PickupIon Trajectories

Sol

ar W

ind

GyratingProtons

Distribution Near Cycloid “Cusp”

IMF

SW

Pickup Ion Trajectories

Surface Crustal Magnetic Field

ConnectedUnconnected

ReconstructedIon Trajectories

Ion Reflection Source Map

26 Event Periods, June 29 – August 31

Lunar Precursor Effects