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Six key observations:

C. D. B. A. E. “Injection”. Six key observations:. 2. C. Pulsations before substorm injection Pulsation/particle energy ramps up before injection Fine structure in pulsations Particle and B are anti-correlated Period of pulsations are different at different azimuthal locations

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Six key observations:

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  1. C D B A E “Injection” Six key observations: 2 C Pulsations before substorm injection Pulsation/particle energy ramps up before injection Fine structure in pulsations Particle and B are anti-correlated Period of pulsations are different at different azimuthal locations Time delayed “injection” onsets 1 1 2 D 5 3 4 B 3 5 6 A E 6

  2. C resonance cavity D B A E Timing Analysis: Precursor D filtered B A linear ~3 s ~4 s Spacecraft separations? Velocities? D  B  A

  3. C resonance cavity D B A E Timing Analysis: EP onset D filtered B A linear ? ~0 s ? ~3 s Spacecraft separations? Velocities? D  B  A

  4. Relation to the Aurora Brightest spot Poleward expansion Westward expansion

  5. Most intense particle injection occurs around the time of the brightest auroral activity. Most intense particle injection coincides with most pronounced westward expansion of WTS The auroral “pre-cursor” shows pulsations, similar to particle pulsations (real ?) Modulation ? Brightest spot ILAT MLT Westward expansion

  6. THEMIS “pre-cursor” • sudden westward expansion • brightest spot •  onset? expansion phase

  7. GOES 11 Y LANL X Timing Analysis: Including GOES 11 and LANL

  8. Comparison with ground stations log Ground THEMIS log

  9. Note: So far, data are only available from low-latitude stations KAG (L=1.22) and MSR (L=1.6). More data might come later. 210 MM THEMIS 210MM

  10. Pseudo-breakup Pseudo-breakup smaller energies compared to substorm decreasing energy

  11. Y Modulations ILAT Precursor ? Cavity MLT Explosive expansive phase onset X Energy ramp Scenario: • flow burst and braking of flow (?) • pressure and B field buildup • diamagnetic current creates cavity • launching of broadband waves • setting up resonances in cavity • cavity growths  Particles are pumped up •  auroral modulations  ground pulsations •  “precursor” • Cavity becomes unstable (ballooning) •  onset • inductive E causes “injection” Two harmonics form inside resonance cavity

  12. Models 1) Yes ? Yes Yes Yes probably Yes Pi2 ? • Cavity formation around B minimum • flow burst and braking of flow • launching of broadband waves • setting up of resonances in cavity • resonances grow • cavity becomes unstable (ballooning) •  breakup • Pi1 oscillations • vortex and tailward expansion Voronkov et al. (2005) 2) • internal instability • earthward gradient of pressure and B • westward traveling Alfven waves • ballooning unstable • pressure and total B are out of phase (Miura, 1989) • (Roux et al., 1991, did not show this?) • inductive E causes “injection” •  breakup • tailward expansion • Does not explain Pi2 frequency (?) What are the observables that distinguish both models? Roux et al. (1991)

  13. ACE

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