Upload
patricia-sparks
View
215
Download
1
Embed Size (px)
Citation preview
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
Measuring the electric potential at the bow shock
Group A: Tutor: S. Bale Crew: L. Xie L. Yang B. Engavale W.-L. Teh
W.-L. Shi X.-G. Zhang
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
Outlines
Introduction Data and Analysis Techniques Present result Work to be done
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
Bow shock transition region from supersonic
upstream flow to subsonic downstream flow.
Density, temperature and fields changes rapidly
Shocks can be found everywhere, near the planets, stars, etc.
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
Bow shock of Earth magnetosphere
return
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
ukE
Solar wind Bow shock Magnetosheath
ukE
dkE
iKT
eKT
KT
e
Purpose of our project is to estimate potential energy in the bow shock region.
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
Energy distribution is earlier studied by J.D. Scudder(1986,1995), but it is not yet understood very clearly.
Very few measurements of potential at the bow shock are available.
Investigate the role of potential in the energy distribution and its dependence on solar wind properties(M, ,)
dei
dsw
uB
usw B
EKTemvEmv ),(
22
2
1
2
1
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
Sharp changing of Variables
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
Data And Analysis TechniquesData Description
FGM1. Magnetic Fields (FGM)
2. Electric Fields (EFW)
3. Plasma density (CIS)
4. Plasma velocity (CIS)
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
Analysis Methods
1. Shock identification
Some physical quantities, namely, B fields, plasma density, plasma velocity, will change rapidly when traversing the shock.
Cluster measures electric fields only in two directions, we want to computethe third component of E field by using this equation.
0 BE
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
One crossing of the shock
2001 Mar 31
Assumptions:
1. Quasi-perpendicular
shock
2. One-dimensional
structure of shock
3. Steady state
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
2. Shock Normal Estimate
Use crossing times approach to estimate the shock normal in our study.
2
1 1
])(ˆ[
N N
vtrrns
Method description:
n
v
rij
2
1 1
])([
N N
kkk trrms
0
km
s12 )]([1
nknnk RrrtNm
N
knnk rrNR1
/1
where
vnm /ˆ
||/1 mv
mvn
ˆ
n=[0.94,-0.2,0.28]
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
3. Coordinates transformation
Normal Incidence Frame
)ˆ(ˆ nVnV uNIF
In this frame, the flow will be directed along the shock normal.
Maximum variance analysis of electric field (MVAE)
3,2,1, 3
1
nnM E
EEEEM E
< > denotes the average
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
4. Electric potential calculation
After transforming the electric fields into the variance space, we integrate the maximum variance of the electric field, which is the normal electric component of the shock, to obtain the electric potential across the shock layer.
The estimate of the start time and end time becomes very important in this calculations of electric potential.
eV 1860Vup=670km/s, Vdn=263km/s, E=1974eV
Min
Int
Max
86BNU
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
Present result
Analyzed 8 shocks (21 Mar 2001)
as a function of Mach number.
2/2u
swmv
e
In order to study this further, we need to study more cases.
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
Work to be done
Cluster data available ⇒ 3 years(2000-2003)
∼100 orbits
200 to 2000 shocks
By assuming each event analysis take 30 min
6 person (8 hrs/day) ⇒ 1 months
back
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
PROJECT
GROUP_ A
GROUP_ B
GROUP_ C
Data analysis + programming
New interesting results,Need detailed analysis
Meeting for the discussion
Few months
Group A: S. Bale(Tutor), B. Engavale, W.L. Shi, W.L. Teh, L. Xie, L. Yang, and X.G. Zhang 13,May 2004
3rd COSPAR Capacity Building Workshop3rd COSPAR Capacity Building Workshop, Beijing, China
LOOKING FORWARD FOR THIS PROJECT
THANKS FOR YOUR ATTENTIONS !