The concept of how magnetosheath plasma can cross the magnetopause is one of the key elements for a global view of the magnetosphere. According to this view, viscous interaction is the main process to produce convection of plasma in the magnetotail, resulting in auroral phenomena, and other related processes. The mechanism is illustrated herein. The key element is that the electric field is not constant, as assumed in reconnection theories, but reverse within the magnetopause current sheet. Particles, representing magnetosheath ions were traced as they impinge upon the magnetopause

Heikkila, W. J.

English

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	 -
-CH-174300) RESEARCH FELATIVE TO
TRANSPORT ACEOSS TEE CAGNETOFAUSE
Report (TPxas Univ. at Dallas,
4soa.)	 lU F HC A02/MF A01
	 CSCL 201
FINAL REPORT
to
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
f rom
Dr. Walter J. Heikkila
Center for Space Sciences
The University of Texas at Dallas
P. 0. Box 830688
Richardson, Texas 75083--0688
ARCH RELATIVE. TO PLASMA TRANSPORT ACROSS THE MAGNETOPAUSE
H85-16636
UnclaE
G3/75 13439
to the reconnection assumptions by assuming a constant electric field in our
magnetospht, ric model. In Figure 4 we have traced a 1 keV proton; the view in
the equatorial plane shows the behavior expected for an eastward current, while
the other view in the magnetic meridian shows a poleward motion, in conformity
with reconnection theories. This shows that our tracing routine does in fact
work correctly. We have also cal.-ulated the energy of the proton, and it does
indeed gain energy (to 2.5 keV).
3. Tracing particles with electric field reversal at the magnetopause.
Next, we assumed an electric field profile which reverses sign of the
E  component at the magnetopause. Now we fine chat the particle does cross the
magnetopause current sheet, as in Figure 5a; there is very little displacement
in the meridian plane, Figure 5b. Because both fields are reversed in the
boundary layer, V F. = E X B/B 2 remains earthward. The particle gains energy,
because nuw it is similar to earthward convection in the plasma sheet on the
nights ide.
The work is still in progress, since it is a very difficult topic, and goes
against the prevailing traffic. An invited paper will be delivered at the
Chapman Conference on Solar Wind-Magnetospheric Coupling to be held at JPL, Feb.
12-15, 1985. We had hoped that we could have included a copy of this paper in
this report. It will point out several features of this work.
a) The electric field must have a curl locally, so that stored
magnetic energy can be tapped; our model does have this curl.
b) As the plasma particles cross the current layer, they first gain
some energy, but they quickly lose all, or most, of it; this agrees with the
finding by Eastman and Hones (1979) that the energy spectrum of the plasma
particles shows hardly any difference on the two sides of the magnetopause.
3
c) The energization of the particles as they convect inward in the
magnetospheric boundary layer may explain the observed spectral 6,anges as
reported by Reiff et al. (1977).
d) Because the net energy (or loss) gain will be small, the total
dissipation by the magnetopause current will not be as high as predicted by
reconnection theories, agreeing with the obs-arvations.
e) This model does agree with the ISEE-1 /2 observations on momentum
changes, as reported by Sonnerup et al. (1981), and so their conclusion (that
the reconnection model is the correct one) is not valid. We must look at energy
changes as well to differentiate between the two models.
f) The frozen-in theorem does not hold, nor should it. The theorem
does hold away from the magnetopause, but within the current layer both the
necessary length and time scales are not satisfied. The magnetopause can be
regarded as a sink of magnetic flux on one side, and a source on the other.
g) This model, with an inductive electric field with a finite electro-
motive force, can be incorporated in a theory of Flux Transfer Events (FTE).
Magnetotail
We have important new ideas on the magnetotail, and especially, on the
Interpretation of ISEE-3 data in the distant tail. However, we have had no
opportunity to do the work on this grant, partly due to slow access to the data.
Thcse new ideas are explained in our newest proposal for a Guest Investigator
on ISEE, submitted in October, 1984 (UTD #850025) and will be presented in
another invited paper at the Chapman Conference on the Magnetotail, to be held
at JPL, October 28-31, 1985.
REFERENCES
W. J. Heikkila, Is There an Electrostatic Field Tangential to the Dayside Mag-
netopause and Neutral Line?, Geophys. Res. Le'ters 2, 154, 1975.
W. J. Heikkila, Impulsive Plasma Transport; Through the Magnetopause, Geophys.
Res. Letters 9, 159, 1982.
W. J. Heikkila, Magnetospheric Topology of Fields and Currents, Magnetospheric
Currents Geophys. Monograph 28, 208, 1983.
W. J. Heikkila, The Electromagnetic Field for an Open Magnetosphere, Magnetic
Reconnection in Space and Laboratory Plasmas Geophys. Monograph 30, 39, 1984.
P. H. Reiff, T. W. Hill, J. L. Burch, Solar Wind Plasma Injection at the Dayside
Magnetospheric Cusp, J. Geophys. Res. 82, 479, 1977.
B. U. 0. Sonnerup, G. Paschmann, I. Papamastorakis, N. Sckopke, G. Haerendel,
S. J. Bame, J. R. Asbridge, J. T. Gosling, and C. T. Russell, Evidence
for Magnetic Field Reconnection at the Earth's Magnetopause, J. Geophys.
Res. 86, 10,049, 1981
Vi
E,0
— TO SUN
Si
sl
1
ISE1 ORB,
MP 6l
(a)
sl	
^^SZ
^^i	 W BOU AAr
rSEE ORg T c
	
rLA r E R
VMS 3
Vet
r
Ep O -	 ® m
	
O
0
n
TO EARTM--*--o	 \ \
Si	 S2
(b)
Fig. 1(a) Dungey's model of the dayside magnetopause. The J x B force produces
a jet of plasma on open field lines, and a positive J . E implies power dissipa-
tion of about 5 x 10 11 watts over the entire frontside magnetopause.
Fig. 1(b) Heikkila's model with the same mnvnetic field topology, but with the
tangential electric field reversing direction. The J x B force also produces
a jet of plasma, but this time toward closed field lines. Here J x E is positive
on one side, but negative on the other; the current perturbation can be regarded
as a dynamo followed by a load.
.I
_Ms.	 ii
PLASMA Y CLOUD
Fig. 1(c) Impulsive penetration is produced by an electrostatic field due to
a charge distribution created by an induction electric field. Charged particles
from the old plasma cloud go through the current sheet along Bn and form a new
plasma cloud on closed magnetic field lines.

Icon" fTART
I
pen a ► w
11
arm v•
O/1v 2 •
s0 vOY 1
(dwTM (111
LIK/
nr
OAO IV
Fig. 3. A model of the total magnetic field near the subsolar magnetopause,
including a dipole geomagnetic field, a constant representing the interplane-
tary magnetic field, and a component due to the magnetopause current. An x-line
is formed at the equator.
rL
1.00
10.20
-0.20
0.05
90.00
90.00
0.00
0.00
9.00
1.00
T
10.00
47.14
.2E-06
0.001
P.O. M
PROTON
KEV	 1.00
X	 - 10.20
Y	 -0.211
Z - 0.OS
VCOL- 90.00
VLM- 90.00
XROT - 0.00
YROT- 0.00
ZROT- -90.00
EOFF-	 1.00
ECON- T
BCON- 10.00
BMAX- 47.14
IPM-0.2E-06
TINC- 6.061
TTIM- 20.00
Fig. 4. Tracing of proton motion, with an initial energy of 1 keV. The upper
curve shows poleward movement, in agreement with two-dimensional reconnection
theories shown in Fig. 1(a); the lower curve shows that the main movement is,
in fact. along the magnetopause contributing to the eastward current, and is
associated with energization (indicated by th,e larger gyrations).
siYa---	 anumb	- . ,. , _ 11	 ...	 _._ _ ._	 _._	 ..........
,V
The concept of how magnetosheath plasma can cross the magnetopause
(Heikkila, 1982) has been one of the key elements for a truly global view of the
magnetosphere (Heikkila, 1983). According to this view, viscous interaction is
the main process to produce convection of plasma in the magnetotail, resulting
in auroral phenomena, and other related processes. The mechanism is illustrated
in Figure 1. The key element here is that the electric field is not constant,
as assumed in reconnection theories, but reverse within the magnetopause current
sheet. A paper was read at the Chapman conference on Magnetic Reconnection
(Heikkila, 1984), included with report, showing the implications of this model.
The main accomplishment of the work done under this grant has been to trace
particles, representing magnetosheath ions, as they impinge upon the
magnetopause.
1. Model of the magnetosphere.
Three kinds of magnetic fields are incorporated, these being a dipole
geomagnetic field, an external interplanetary field, and fields due to current
sheets carried by the plasma.	 The latter can include a cross —tail current, as
well as a magnetopause current. For the work described below, a magnetopause
current was included, as shown in Figure 2. The combined magnetic field lines
are shown in Figure 3; the topology does include an X— line in the sub—solar
region.
2. Tracing particles with the reconnection model.
Reconnection theories are based upon an electric field that is assumed to
be constant near the X—line, pointing toward dusk. 	 Since the magnetopause
current also points in the same direction, E.J is positive, implying an energy
dissipation of 10 11 to 10 12 watts (Heikkila, 1975). So far, there is still no
conclusive evidence that this dissipation is ooserved, which is why we are
seeking alternative models. However, we can trace particles (ions) appropriate
.— - x,:


Research relative to plasma transport across the magnetopause

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