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BACK Parallel electric fields in space Observations by Cluster satellites inside the auroral zone at altitudes above the main acceleration region Presentation of Master Thesis by Erik Bergman Dept.: Astronomy and Space Physics Instructor: Andris Vaivads Examiner: Annika Olsson
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BACK Contents Introduction Handling the data Selection strategy Results Instrumental effects Conclusions
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BACK Introduction Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions Discrete auroras Auroral oval Potential models Predictions of U and O-potentials EFW instrument
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BACK Discrete auroras Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions Discrete auroral arcs: Caused by electrons accelerated by parallel E-fields usually at 1-2 R E North-South, 100 m – 80 km, typically 5 km Mapped to Cluster altitude (~4.5 R E ) this equals 50 km At Cluster speed (~5 km/s) the size of parallel E-fields would be ~10 seconds
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BACK Potential models Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions
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BACK Predictions of U and O-pot Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions Northern hemisphere perp para 10 s
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BACK Electric Field and Wave experiment Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions Four identical probes Voltage mode, to measure electric fields, only in spinplane Current mode, to measure density and temperature of plasma
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BACK Handling the data Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions Coordinate systems Calculations and assumptions Filtering
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BACK Coordinate systems Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions
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BACK Calculations and assumptions Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions
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BACK Filtering Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions
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BACK Selection strategy Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions Orbits Quicklook plots Overview plots Catagories
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BACK Orbits Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions Middle of March o o
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BACK Quicklook Plot Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions
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BACK Overview Plot Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions
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BACK Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions 500 zero crossings (Jan-May, 2001-2002) 57 events selected for closer inspection Divided into four sub catagories 16 – No activity 23 – No perpendicular activity 5 – Too active 13 – Good events 5 events selected from the good Catagories
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BACK Results Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions Parallel DC electric fields Double layers and solitary waves Waves
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BACK Parallel DC electric fields Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions
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BACK Parallel DC electric fields Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions All electric fields are upwards
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BACK Double layers and solitary waves Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions
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BACK DL and SW theory Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions Accompanied by a decrease in plasma density
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BACK Waves Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions
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BACK Instrumental effects Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions Wake effects Physical Potential Offsets Interference from WHISPER
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BACK Conclusions Contents Introduction Handle data Sel. Strategy Results Instr. effects Conlusions Possible interpretations of the results Upward ~1 mV/m parallel E-fields Too small, could be instrumental effects Could be U associated (not likely at this altitude) Could be lower part of O U on top of O (not probable) Lack of downward parallel E-fields Cluster measure above O, too high altitude Downward fields associated with O should be ~0.1 mV/m at this altitude, i.e. not measurable
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BACK The End Thank you for listening
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BACK Extra plots
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BACK 2002-01-10
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BACK SW LIST DC LIST
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BACK UP SW LIST DC LIST
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BACK UP SW LIST DC LIST
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BACK 2002-02-06
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BACK SW LIST DC LIST
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BACK 2002-02-17 BACK SW LIST DC LIST
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BACK 2002-03-06
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BACK SW LIST DC LIST WAVES
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BACK UP SW LIST DC LIST WAVES
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BACK 2002-03-18
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