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Parallel electric fields in space Observations by Cluster satellites inside the auroral

This presentation discusses the observations of parallel electric fields in space by Cluster satellites inside the auroral zone at altitudes above the main acceleration region. The Master Thesis by Erik Bergman covers topics such as handling the data, selection strategy, results, instrumental effects, and conclusions.

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Parallel electric fields in space Observations by Cluster satellites inside the auroral

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  1. 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

  2. Introduction Handling the data Selection strategy Results Instrumental effects Conclusions Contents

  3. Contents Introduction  Handle data  Sel. Strategy  Results  Instr. effects  Conlusions Discrete auroras Auroral oval Potential models Predictions of U andO-potentials EFW instrument Introduction

  4. Contents Introduction  Handle data  Sel. Strategy  Results  Instr. effects  Conlusions Discrete auroras • Discrete auroral arcs: • Caused by electrons accelerated by parallelE-fields usually at 1-2 RE • North-South, 100 m – 80 km, typically 5 km • Mapped to Cluster altitude (~4.5 RE) this equals 50 km • At Cluster speed (~5 km/s) the size of parallel E-fields would be ~10 seconds

  5. Contents Introduction  Handle data  Sel. Strategy  Results  Instr. effects  Conlusions Potential models

  6. Contents Introduction  Handle data  Sel. Strategy  Results  Instr. effects  Conlusions Predictions of U and O-pot perp para 10 s Northern hemisphere

  7. 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 Electric Field and Wave experiment

  8. Contents  Introduction Handle data  Sel. Strategy  Results  Instr. effects  Conlusions Coordinate systems Calculations and assumptions Filtering Handling the data

  9. Contents  Introduction Handle data  Sel. Strategy  Results  Instr. effects  Conlusions Coordinate systems

  10. Contents  Introduction Handle data  Sel. Strategy  Results  Instr. effects  Conlusions Calculations and assumptions

  11. Contents  Introduction Handle data  Sel. Strategy  Results  Instr. effects  Conlusions Filtering

  12. Contents  Introduction  Handle data Sel. Strategy  Results  Instr. effects  Conlusions Orbits Quicklook plots Overview plots Catagories Selection strategy

  13. Contents  Introduction  Handle data Sel. Strategy  Results  Instr. effects  Conlusions Orbits o o Middle of March

  14. Contents  Introduction  Handle data Sel. Strategy  Results  Instr. effects  Conlusions Quicklook Plot

  15. Contents  Introduction  Handle data Sel. Strategy  Results  Instr. effects  Conlusions Overview Plot

  16. Contents  Introduction  Handle data Sel. Strategy  Results  Instr. effects  Conlusions Catagories • 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

  17. Contents  Introduction  Handle data  Sel. Strategy Results  Instr. effects  Conlusions Parallel DC electric fields Double layers and solitary waves Waves Results

  18. Contents  Introduction  Handle data  Sel. Strategy Results  Instr. effects  Conlusions Parallel DC electric fields

  19. Contents  Introduction  Handle data  Sel. Strategy Results  Instr. effects  Conlusions Parallel DC electric fields All electric fields are upwards

  20. Contents  Introduction  Handle data  Sel. Strategy Results  Instr. effects  Conlusions Double layers and solitary waves

  21. Contents  Introduction  Handle data  Sel. Strategy Results  Instr. effects  Conlusions Accompanied by a decrease in plasma density DL and SW theory

  22. Contents  Introduction  Handle data  Sel. Strategy Results  Instr. effects  Conlusions Waves

  23. Contents  Introduction  Handle data  Sel. Strategy  Results Instr. effects  Conlusions Wake effects Physical Potential Offsets Interference from WHISPER Instrumental effects

  24. 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 Conclusions

  25. Thank you for listening The End

  26. Extra plots

  27. 2002-01-10

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  31. 2002-02-06

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