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Wave-particle interactions in the magnetosheath/magnetosphere boundary layers

Wave-particle interactions in the magnetosheath/magnetosphere boundary layers. Alexandra Teste, G. K. Parks, M. Wilber, N. Lin SSL, University of California, Berkeley. 17th Cluster Workshop Uppsala Universitet, Sweden 2 nd Waves session Thursday, May 14, 2009.

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Wave-particle interactions in the magnetosheath/magnetosphere boundary layers

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  1. Wave-particle interactions in the magnetosheath/magnetosphere boundary layers Alexandra Teste, G. K. Parks, M. Wilber, N. Lin SSL, University of California, Berkeley 17th Cluster Workshop Uppsala Universitet, Sweden 2nd Waves session Thursday, May 14, 2009 Acknowledgement to D. Fontaine for providing access to the electron data and to Y. Voitenko for discussing the wave data

  2. 30 20 10 Zgse (Re) 0 104 -10 ions -20 103 Energy (eV) -30 102 20 10 0 -10 -20 Xgse (Re) 101 e- (anti-//) 104 103 Energy (eV) ergs/(cm².s.sr.eV) 102 |B| 40 By Bz 0 Bfield (nT) Bx -40 10 Ez 5 Ex Ey Efield (mV/m) 0 -5 01:30 01:32 01:34 01:36 01:38 01:40 01:42 A. Teste 17th Cluster Workshop May 14, 2009 Magnetospheric event within the magnetosheath: May 2, 2003 • Cluster 3 at ~ (6.6, -5.8, 11.1)gse Re • southward turning of IMF • BL = Msheath population accelerated ~ 300 eV & heated ~ 900 eV

  3. Msphere Msphere Msheath outer inner Msheath outer inner -10 -5 0 5 10 -10 -5 0 5 10 Velocity (1.e4 km/s) Velocity (1.e4 km/s) f (s3/m6) 10-14 10-18 f (s3/m6) 10-14 10-22 iso. diff. msph. e- 10-18 //, anti//  10-22 Msheath  diff. msph. e- Msphere A. Teste 17th Cluster Workshop May 14, 2009 Internal structure and characteristics of the boundary layer (BL) e- (//) e- () ergs/(m².s.sr.eV) Energy (eV) e- (anti-//) BL  direction diffusion across inner & outer BL // & anti// directions diffusion across inner BL only • Our study: characterization of these 2 regions from particle and wave points of view • Robert et al., 2005; Fear et al., 2005 & Owen et al., 2008: FA ct-streaming BL pop. & inner/outer BL

  4. e- (//) e- () Energy (eV) e- (anti-//) Mag. 1000 nT²/Hz 100 Pitch angle (°) cnts/sec 10 Frequency (Hz) 104 103 V²/(m².Hz) 102 101 A. Teste 17th Cluster Workshop May 14, 2009 Waves in the magnetospheric domain ergs/(m².s.sr.eV) High E: 1500-9000 eV Elec. 01:30 01:32 01:34 01:36 01:38 01:40 01:42 • Magnetospheric e- with peaks at intermediate angles  conic-like distributions 01:30 01:32 01:34 01:36 01:38 01:40 01:42 • Typical ES waves(Anderson et al., 1982): - Upper hybrid waves: f~fuH~6.6 kHz: conic-like e- - ES e- cyclotron waves (f~fce ~1.1 kHz), 1st harmo. f ~2.2 kHz, Bernstein (n=2-5): 2 tenuous loss cones

  5. e- (//) e- () Energy (eV) e- (anti-//) Mag. 1000 nT²/Hz 100 10 Frequency (Hz) 104 103 V²/(m².Hz) 102 101 - EM e- cyclotron (EMEC) waves: f~400 Hz<fce, right-handed, (k,B)~10°-30°:  conic-like e- A. Teste 17th Cluster Workshop May 14, 2009 Waves in the magnetospheric domain ergs/(m².s.sr.eV) High E: 1500-9000 eV Elec. 01:30 01:32 01:34 01:36 01:38 01:40 01:42 • Typical EM waves(Anderson et al., 1982): with broadband ES spikes

  6. Mag. 1000 • EMEC waves (outer BL) 100 10 Elec. Frequency (Hz) 104 103 V²/(m².Hz) •  ~ 710 Hz • ce ~ 1.4 kHz 102 101 with N = 0 and v  3.2 keV = diffused Mspheric e- • (k,B) ~10°- 30° 10-5 A. Teste 17th Cluster Workshop May 14, 2009 10-7 B (nT²/Hz) 10-9 10-11 0.8 T/T// -1 0.4 0.0 -0.2 Waves in the boundary layer e- (//) e- () Energy (eV) ergs/(m².s.sr.eV) e- (anti-//) nT²/Hz Freq. (Hz) at ~ 700 Hz 1.2 < Ee- < 15 keV 01:30 01:32 01:34 01:36 01:38 01:40 01:42 01:30 01:32 01:34 01:36 01:38 01:40 01:42 EMEC waves: f < fce, RH polarized, // to B Outer BL: anisotropic diffusion of Mspheric pop.  EMEC waves

  7. e- () ergs/(m².s.sr.eV) Energy (eV) e- (anti-//) Msphere f (s3/m6) Msphere Msheath outer inner f (s3/m6) Msheath f (s3/m6) outer inner 10-14 10-14 10-14 f (s3/m6) 10-18 10-18 10-18 10-22 10-22 10-22 iso. diff. msph. e- -10 -5 0 5 10 -10 -5 0 5 10 -10 -5 0 5 10 -10 -5 0 5 10 Velocity (1.e4 km/s) Velocity (1.e4 km/s) Velocity (1.e4 km/s) Velocity (1.e4 km/s) //, anti//  Msheath  diff. msph. e- Msphere A. Teste 17th Cluster Workshop May 14, 2009 SUMMARY SKETCH BL  direction diffusion across inner & outer BL EM e- cycl. waves // & anti// directions diffusion across inner BL only

  8. Conclusion: The boundary layer is composed of: • outer BL: - Msheath plasma: FA, counter-streaming and only accelerated - anisotropic diffusion of Mspheric plasma  distribution unstable to EMEC waves • inner BL:- Msheath plasma: FA, counter-streaming, accelerated & heated and denser than outer BL - isotropic diffusion of Mspheric plasma - weak wave activity if any Questions: • what is the heating process of low E e- in inner BL & why isn’t at work in the outer BL too? • why is diffusion anisotropic in the outer BL? • why do the spikes gather together when EM e- cyclotron waves are observed? • …

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