Ali-Reza Khesali*, Mohmmad-Ali Bagherian
Department of Physics, Faculty of Basic Sciences,
University of Mazandaran,
P.O. Box 47416-1467, Babolsar, Iran
Abstract.
The nonlinear evolution of thermally unstable
disturbances in
plasma are investigated within the framework of one-dimensional fluid
equations. The processes of heating and radiative cooling (cooling function)
of the
optically thin plasma are taken into account. A new statistical approach
is
presented to study the thermal instability to the interstellar medium
ISM of an
optically thin unmagnetized plasma. This approach makes possible to
simplify
the set of equations describing the instability, and using Lagrangian
coordinates,
to investigate the nonlinear dynamics of the instability analytically.
The equations are solved both analytically and numerically by successive
approximations
assuming a thermal conduction coefficient T and cooling function
coefficient of
type
T a - T b . We discuss the nonlinear development of the isobaric mode of thermal instability in the atomic molecular clouds of ISM.
Keywords: Instability: general - ISM