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

• BL = Msheath population accelerated ~ 300 eV & heated ~ 900 eV

Magnetospheric event within the magnetosheath: Magnetospheric event within the magnetosheath: May 2, 2003May 2, 2003

• Cluster 3 at ~ (6.6, -5.8, 11.1)gse Re• southward turning of IMF

A. Teste 17th Cluster Workshop May 14, 2009

01:30 01:32 01:34 01:36 01:38 01:40 01:42

Ene

rgy

(eV

)

102

103

104

101

ions

e- (anti-//)

Bx

ByBz

|B|

ExEy

Ez

Efie

ld (

mV

/m)

-5

5

10

0

Bfie

ld (

nT)

0

40

-40

Ene

rgy

(eV

)

102

103

104

ergs

/(cm

².s.

sr.e

V)

Xgse (Re)20 10 0 -10 -20

Zgs

e (R

e) 10

20

30

0

-10

-20

-30

Ene

rgy

(eV

)

e- (//)

e- (anti-//)

e- ()

ergs

/(m

².s.

sr.e

V)

Msheath

Msphere

outer inner

diffusion across inner & outer BL

direction

Internal structure and characteristics of the boundary layer Internal structure and characteristics of the boundary layer (BL)(BL)

diffusion across inner BL only

// & anti// directions

Msheath

Msphere

outer inner

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

BL

A. Teste 17th Cluster Workshop May 14, 2009

-10 -5 0 5 10Velocity (1.e4 km/s)

f (s3/m6)

10-18

10-14

10-22iso. diff. msph. e-

-10 -5 0 5 10Velocity (1.e4 km/s)

diff. msph. e-

10-14

10-18

10-22

f (s3/m6)

//, anti//MsheathMsphere

Ene

rgy

(eV

)

e- (//)

e- (anti-//)

e- ()

01:30 01:32 01:34 01:36 01:38 01:40 01:42

ergs

/(m

².s.

sr.e

V)

01:30 01:32 01:34 01:36 01:38 01:40 01:42

High E: 1500-9000 eV

• Typical ES waves (Anderson et al., 1982):

Waves in the magnetospheric domainWaves in the magnetospheric domain

A. Teste 17th Cluster Workshop May 14, 2009

Pitc

h an

gle

(°)

cnts

/sec

101

102

103

104

100

10

1000 Mag.

Fre

quen

cy (

Hz)

V²/

(m².

Hz)

nT²/

Hz

Elec.

- 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

• Magnetospheric e- with peaks at intermediate angles conic-like distributions

Ene

rgy

(eV

)

e- (//)

e- (anti-//)

e- ()

01:30 01:32 01:34 01:36 01:38 01:40 01:42

ergs

/(m

².s.

sr.e

V)

High E: 1500-9000 eV

• Typical EM waves (Anderson et al., 1982):

Waves in the magnetospheric domainWaves in the magnetospheric domain

A. Teste 17th Cluster Workshop May 14, 2009

101

102

103

104

100

10

1000 Mag.

Fre

quen

cy (

Hz)

V²/

(m².

Hz)

nT²/

Hz

Elec.

- EM e- cyclotron (EMEC) waves: f~400 Hz<fce, right-handed, (k,B)~10°-30°: conic-like e-

with broadband ES spikes

Ene

rgy

(eV

)

e- (//)

e- (anti-//)

e- ()

01:30 01:32 01:34 01:36 01:38 01:40 01:42

ergs

/(m

².s.

sr.e

V)

EMEC waves: f < fce, RH polarized, // to B

nT²/

Hz

Outer BL: anisotropic diffusion of Mspheric pop. EMEC waves

A. Teste 17th Cluster Workshop May 14, 2009

Waves in the boundary layerWaves in the boundary layer

100

10

1000 Mag.

V²/

(m².

Hz)

101

102

103

Fre

quen

cy (

Hz)

104Elec.

Fre

q. (

Hz)

-0.2

T/T

// -1

0.0

0.4

0.8

B (

nT²/

Hz)

10-11

10-9

10-7

10-5

• ~ 710 Hz• ce ~ 1.4 kHz

EMEC waves (outer BL)

• (k,B) ~10°- 30°

with N = 0 and v 3.2 keV = diffused Mspheric e-

ceNvk ////

01:30 01:32 01:34 01:36 01:38 01:40 01:42

1.2 < Ee- < 15 keV

at ~ 700 Hz

Ene

rgy

(eV

)e- (anti-//)

e- ()

ergs

/(m

².s.

sr.e

V)

Msheath

Msphere

outer inner

diffusion across inner & outer BL

direction

SUMMARY SKETCHSUMMARY SKETCH

diffusion across inner BL only

// & anti// directions

Msheath

Msphere

outer inner

BL

A. Teste 17th Cluster Workshop May 14, 2009

-10 -5 0 5 10Velocity (1.e4 km/s)

f (s3/m6)

iso. diff. msph. e-

-10 -5 0 5 10Velocity (1.e4 km/s)

diff. msph. e-

10-14

10-18

10-22

f (s3/m6) //, anti//MsheathMsphere

-10 -5 0 5 10Velocity (1.e4 km/s)

10-14

10-18

10-22

f (s3/m6)

-10 -5 0 5 10Velocity (1.e4 km/s)

10-14

10-18

10-22

f (s3/m6)

EM e- cycl. waves

Conclusion: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: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?

• …