Page 25 - swp0000.dvi

13
where  =(34 0 ) ,  0 is initial density of the dust,   is the dust
charge,     is dust thermal energy. For Γ  À 1 plasma is strongly coupled

[60, 61] while weakly coupled dusty plasma occurs for Γ  ¿ 1 [62, 63].

1.8 Dusty Plasmas in Space and Laboratory

1.8.1 In Space

In space environments [64], dust grains are found in cometary tails,

noctilucent clouds and planetary rings etc.

Interplanetary Space: space between planets contains electromagnetic ra-

diation, hot plasmas, solar wind, cosmic rays, dust particles and magnetic
fields from the Sun. Dust grains are very small (0.0005 cm in radius) grains

and become the effective materials in our solar system. Dusty grains in

earth’s surface are about 200  [65]. These grains are obtained from aster-

oidal material collisions with comets [66]. The typical dust-laden plasma
−3
−4
parameters in interstellar-clouds are   ' 10 −3 − 10    ' 12   '
−3
4
−7
10   =02    ' 0  −3 and   ≤ 03 [49].
Comets: comet is a ball of ice-dust grain looks like a star with a tail
and have three parts:

1- nucleus, 2- head (coma) and 3- tail see Fig.(1.2).

14