Environmental Engineering Reference
In-Depth Information
Figure 6.9 The rings of Saturn contain dust particles from its satellites and are supported by the
action of its magnetic field and the solar wind [87].
project provided evidence for the dust parameters [92, 93] and plasma parame-
ters [26, 94] from Saturn's E ring. The solar wind also influences transport of dust
particles from Enceladus [24, 90, 95]. The number density of the plasma that re-
sults from the interaction of the magnetic field of Saturn and the solar wind is
N 0
100 cm 3 , the electron temperature is 10-100 eV [96], and the magnetic
field influences significantly the properties of this plasma. Ions of various types ex-
ist in a ring plasma, and basic types of ions are OH C and H 2 O C with temperatures
of the order of 10 3 K.
Let us analyze the parameters of a cosmic dusty plasma on the basis of the above
analysis. Taking for definiteness r 0
D
30
D
1
μ
mand T e
D
T i
D
30 eV, we obtain
10 4 .Next,
from (6.22) x
D
2.5, which corresponds to the particle charge
j
Z
jD
5
30 cm 3 [88], we obtain N p R 0
10 5 cm 1 , which is small compared with N 1/ p , that is, scattering of electrons and
ions of the solar wind by each particle proceeds independently. Note that we ob-
tain an overestimated value for the particle charge because the total number den-
sity of particle charge N p
taking the number density of particles N p
D
10 6 cm 3 exceeds significantly the observed value
j
Z
j
10 2 cm 3 [96]. Moreover, from the observed number density of electrons
and ions it follows that
N 0
3, and the negative charge of this plasma is con-
nected to particles, whereas ions are located in the space between particles and
N i
j
Z
j
10 2 cm 3 . But this is large compared with the number density of fast elec-
trons and protons in the solar wind on the Saturn level, which is approximately
0.1 cm 3 .
Let us consider the problem regarding this plasma from another standpoint. For-
mation of a dusty plasma of the solar system results from interaction of the solar
wind with an interplanetary dust. As a result of mixing, a dusty plasma is formed,
and the number density of charged particles in this plasma exceeds that in the solar
wind by several orders of magnitude. Above, we verified this for the dusty plasma
of the rings of Saturn, and the same can be done for other types of dusty plasma
occurring in the solar system. In particular, in the case of comets [27, 28], comet
tails result from the interaction of the solar wind with comet dust and comet ions
(see Figure 6.10 [97]). Although the magnetic properties of comets are important
for the properties of this plasma [29], processes in the field of charged particles
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