Electric Fields from Ion Distribution Images Electric Fields from - - PowerPoint PPT Presentation

Electric Fields from Ion Distribution Images Electric Fields from Ion Distribution Images

• n Swarm
• n Swarm

David Knudsen

University of Calgary, Alberta, Canada

Contributors: Johnathan Burchill, NRCan, Ottawa Laureline Sangalli, PhD Student, Calgary

Uppsala

1) Swarm 2) Thermal Ion Imaging 3) Sounding Rocket Examples IPELS 7 August 2007

• Precision B (vector and scalar)
• E from -vixB (2 & 16 Hz)
• Ti, Te, ne
• 3-axis stabilized
• ~85-88° inclination
• 2 satellites at ~450 km, laterally separated by 10’s km
• 1 satellite at ~530 km, displaced several hours in local time
• Nominal mission 2010-2014

The Swarm Mission The Swarm Mission

Why Why use use E E = =

• v
• vi

i x B ?

x B ?

• E-field booms difficult on a non-spinning platform
• Booms induce drag and affect stability in LEO
• Extensive orbital flight heritage (Heelis, Hanson et al.)

RE + 450km RE 3485km 1233km RE + 450km RE 3485km 1233km RE + 450km RE 3485km 1233km RE + 110km 10RE RE + 450km RE 3485km 1233km RE + 110km 10RE RE + 450km RE 3485km 1233km RE + 110km 10RE RE + 450km RE 3485km 1233km RE + 110km RE = Earth radius ~ 6371km

Magnetic Field Contributions Magnetic Field Contributions as Seen on Orbit as Seen on Orbit

1) Swarm 2) Thermal Ion Imaging 3) Sounding Rocket Examples IPELS 7 August 2007

100 km 200 km 500 km Thermosphere

B0

Ionosphere

E

~ 101-2 mV/m

j|| B0 B

~ 101-2 nT t j

= t

• r

E

• “

“External External” ” Magnetic Field Sources Magnetic Field Sources

100 km 200 km 500 km Thermosphere

B0

Ionosphere

E

~ 101-2 mV/m

j|| B0 B,ext

~ 101-2 nT t j

= t

• r

E

• “

“External External” ” Magnetic Field Sources Magnetic Field Sources

Sz = r E r H

( ) ˆ

z = PE2

z

2, 16 2, 16 3 mV/m 3 mV/m 0.3 mV/m 0.3 mV/m E E 50 50 < 1 < 1 nT nT B B 2, 16 2, 16 50 K @ 50 K @ 0.1 0.1 eV eV 10 K 10 K T Ti

i,

, T Te

e

16 16 1% 1% 10 101

1 cm

cm-3

• 3

n ne

e

2, 16 2, 16 3 3 μ μW/m W/m2

2

0.1 0.1 μ μW/m W/m2

2

S = S = ExH ExH 2, 16 2, 16 50 50 m/s m/s 6 m/s 6 m/s v vi

i

Rate Rate (s (s-1

• 1)

) Accuracy Accuracy (2 (2 ) ) Resolution Resolution Parameter Parameter

Measurement Measurement Performance Performance

Magnetic field magnitude (ASM) and vector components (VFM) Electric field vector components

Plasma density (in combination with GPS) Ion drift velocity vector (EFI) Ion and electron temperature (EFI)

Air drag (ACC, GPS) Position, velocity, time, attitude (GPS, STR)

GPS Patch Antennas Optical Bench (Vector Field Magnetometer + Star Tracker Assembly) Absolute Scalar Magnetometer Accelerometer Electric Field instrument

(CNES/LETI)

Courtesy: EADS, astrium

Swarm Instruments Swarm Instruments

CCD

phosphor MCPs

Uppsala

The Swarm CEFI The Swarm CEFI

1) Swarm 2) Thermal Ion Imaging 3) Sounding Rocket Examples IPELS 7 August 2007

E/q ~ 5V

Electrostatic Analyzer

Emax/q ~ V/3 Compare: “Top-hat” Carlson et al. [1983] Distribution Imager [Whalen et al., 1994]

• Sensitive to lower energies
• 2-D, energy/angle imaging

Ion Distribution Function Imaging Ion Distribution Function Imaging

• velocity 2-D
• E = -vxB
• temperature
• anisotropies

Ion distribution function f(v)

vx

vz (km/s)

Phosphor, CCD x y

• r

(simulation)

1990 2010

FREJA Swarm ePOP

2000 2005 1995

GEODESIC Cusp JOULE J-II

Development of the Thermal Particle Imager

O+ H+

Ion Flows within an Ion Flows within an Alfvén Alfvén Wave (GEODESIC Rocket) Wave (GEODESIC Rocket)

1) Swarm 2) Thermal Ion Imaging 3) Sounding Rocket Examples IPELS 7 August 2007

1) Swarm 2) Thermal Ion Imaging 3) Sounding Rocket Examples IPELS 7 August 2007

Burchill [2003]

Ion Ion drift/ExB drift/ExB comparison (Sub-orbital platform) comparison (Sub-orbital platform)

Ion Temperature Ion Temperature

JOULE Sounding rocket

• J. Clemmons
• L. Sangalli

~0.1 eV increase inside arc Ion temperature enhancement within an auroral arc...

Conclusions Conclusions

• 2-D thermal distributions up to 125 s-1
• More information: Knudsen et al., Rev. Sci. Instr., 2003

Ion Heating Examples (Sub-orbital platform) Ion Heating Examples (Sub-orbital platform)

Burchill et al. [2004] TAI to 10 eV

Sub-orbital examples JOULE Sounding rocket [L. Sangalli] GEODESIC sounding rocket

Heating ~0.1 eV 1) Swarm 2) Thermal Ion Imaging 3) Sounding Rocket Examples IPELS 7 August 2007

S = ExH

Knudsen [1990]

1) Mission 2) CEFI Instrument 3) Science Themes

M-I Coupling: M-I Coupling: Thermospheric Thermospheric Driver Driver

x y

• r

Sample CEFI image for 20% H+, 80% O+, Vx = 7600 m/s, Vy = 3800 m/s, Ti = 0.1 eV, s/c = -1 V.

O n-board image reduction O n-board image reduction

f(Ti) f(vr, s/c)

Telemetry: 16, 2-D moment estimates per second 2, 1-D profiles per second 1 full image each 128 s

Science Theme: Ion Heating and Outflow

Burchill et al. [2004] TAI to 10 eV

Sub-orbital examples JOULE Sounding rocket [L. Sangalli] GEODESIC sounding rocket [Burchill, 2004]

Heating ~0.1 eV

Plasma Plasma instabilities at all latitudes (IV) instabilities at all latitudes (IV)

• Can relate n/n, vi and E to 1% at 16 s-1 (500 m)
• Ti at 2 s-1

Ion Ion heating and outflow (V) heating and outflow (V)

Burchill et al. [2004]

Can telemeter one full distribution each ~5 minutes.

• 3-D global ion circulation with 6 m/s resolution, 2 or 16 Hz
• Sources of ion heating - 5 meV (50 K) accuracy

Sampling at Satellite Altitude (400km) Sampling at Satellite Altitude (400km)

Swarm Mission Science O bjectives Swarm Mission Science O bjectives

Primary

• Core Dynamics and Geodynamo Processes
• Lithospheric Magnetisation
• 3-D Electrical Conductivity of the Mantle
• Magnetospheric and Ionospheric Current Systems

Secondary

• Ocean Circulation and its Magnetic Signature
• Magnetic Forcing of the Upper Atmosphere

Must remove ionospheric B