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

Electric Fields from Ion Distribution Images Electric Fields from Ion Distribution Images on Swarm on 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

The Swarm Mission The Swarm Mission • Precision B (vector and scalar) • E from - v i x B (2 & 16 Hz) • T i , T e , n e • 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

Why use use E E = = -v -v i x B ? Why i 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.)

Magnetic Field Contributions Magnetic Field Contributions as Seen on Orbit as Seen on Orbit 10R E 10R E 10R E R E + R E + R E + R E + R E + R E + 450km 450km 450km 450km 450km 450km R E + R E + R E + R E + 110km 110km 110km 110km R E R E R E R E R E R E 3485km 3485km 3485km 3485km 3485km 3485km 1233km 1233km 1233km 1233km 1233km 1233km R E = Earth radius ~ 6371km 1) Swarm 2) Thermal Ion Imaging 3) Sounding Rocket Examples IPELS 7 August 2007

“External External” ” Magnetic Field Sources Magnetic Field Sources “ 500 km E � ~ 10 1-2 mV/m j || � B � ~ 10 1-2 nT B 0 t � • r � = t 200 km Ionosphere j E � 100 km Thermosphere B 0

“External External” ” Magnetic Field Sources Magnetic Field Sources “ S z = r E �� r � P E 2 500 km ( ) � ˆ E � H z = � z ~ 10 1-2 mV/m j || � B � ,ext ~ 10 1-2 nT B 0 t � • r � = t 200 km Ionosphere j E � 100 km Thermosphere B 0

Measurement Performance Performance Measurement -1 ) Parameter Resolution Accuracy Rate (s (s -1 ) Parameter Resolution Accuracy Rate (2 � ) (2 � ) v i v 6 m/s 50 m/s m/s 2, 16 6 m/s 50 2, 16 i E E 0.3 mV/m 3 mV/m 2, 16 0.3 mV/m 3 mV/m 2, 16 , T 10 K 10 K 50 K @ 0.1 0.1 eV eV 2, 16 T i T i , T e 50 K @ 2, 16 e 10 1 1 cm cm -3 -3 n e 1% 16 n 10 1% 16 e B B < 1 nT nT 50 < 1 50 2 2 W/m 2 W/m 2 0.1 μ 3 μ S = ExH S = ExH 0.1 μ W/m 3 μ W/m 2, 16 2, 16

Swarm Instruments Swarm Instruments � Magnetic field magnitude (ASM) and vector components (VFM) � Electric field vector components Absolute Scalar Magnetometer Plasma density (in combination with GPS) (CNES/LETI) Ion drift velocity vector (EFI) Ion and electron temperature (EFI) � Air drag (ACC, GPS) � Position, velocity, time, attitude (GPS, STR) Optical Bench (Vector Field GPS Patch Magnetometer + Star Tracker Antennas Assembly) Electric Field instrument Courtesy: EADS, astrium Accelerometer

The Swarm CEFI The Swarm CEFI MCPs phosphor CCD Uppsala 1) Swarm 2) Thermal Ion Imaging 3) Sounding Rocket Examples IPELS 7 August 2007

Electrostatic Analyzer Distribution Imager Compare: “Top-hat” [ Whalen et al ., 1994] Carlson et al . [1983] E max /q ~ � V/3 E/q ~ 5 � V • Sensitive to lower energies • 2-D, energy/angle imaging

Ion Distribution Function Imaging Ion Distribution Function Imaging v z (km/s) Ion distribution function f( v ) v x Phosphor, CCD y r • velocity 2-D � • E = - v x B x • temperature • anisotropies (simulation)

Development of the Thermal Particle Imager FREJA ePOP GEODESIC Cusp JOULE J-II Swarm H+ O+ 1990 1995 2000 2005 2010

Ion Flows within an Alfvén Alfvén Wave (GEODESIC Rocket) Wave (GEODESIC Rocket) Ion Flows within an 1) Swarm 2) Thermal Ion Imaging 3) Sounding Rocket Examples IPELS 7 August 2007

Ion drift/ExB drift/ExB comparison (Sub-orbital platform) comparison (Sub-orbital platform) Ion Burchill [2003] 1) Swarm 2) Thermal Ion Imaging 3) Sounding Rocket Examples IPELS 7 August 2007

Ion Temperature Ion Temperature JOULE Sounding rocket Ion temperature J. Clemmons enhancement within an auroral arc... L. Sangalli ~0.1 eV increase inside 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) Sub-orbital examples GEODESIC sounding rocket JOULE Sounding rocket [ L. Sangalli ] Burchill et al. [2004] TAI to 10 eV Heating ~0.1 eV 1) Swarm 2) Thermal Ion Imaging 3) Sounding Rocket Examples IPELS 7 August 2007

M-I Coupling: Thermospheric Thermospheric Driver Driver M-I Coupling: S = ExH Knudsen [1990] 1) Mission 2) CEFI Instrument 3) Science Themes

O n-board image reduction O n-board image reduction y f( v r , � s/c ) r � f( T i ) x Telemetry: Sample CEFI image for 20% H + , 80% O + , V x = 7600 m/s, V y = 3800 m/s, T i = 0.1 eV, 16, 2-D moment estimates per second � s/c = -1 V. 2, 1-D profiles per second 1 full image each 128 s

Science Theme: Ion Heating and Outflow Sub-orbital examples GEODESIC sounding rocket [ Burchill , 2004] JOULE Sounding rocket [ L. Sangalli ] Burchill et al. [2004] TAI to 10 eV Heating ~0.1 eV

Plasma instabilities at all latitudes (IV) instabilities at all latitudes (IV) Plasma • Can relate � n / n , v i and E to 1% at 16 s -1 (500 m) • T i at 2 s -1

Ion heating and outflow (V) heating and outflow (V) Ion • 3-D global ion circulation with 6 m/s resolution, 2 or 16 Hz • Sources of ion heating - 5 m eV (50 K) accuracy Can telemeter one full distribution each ~5 minutes. Burchill et al. [2004]

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 Must remove • Lithospheric Magnetisation ionospheric � B • 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