Publication date: Apr 2014
Abstract:
The problem of the transition from gas to plasma in gravitating
axisymmetric structures is addressed under the assumption of having
initial and final states realized by kinetic Maxwellian-like equilibria.
In astrophysics, the theory applies to accretion-disc scenarios around
compact objects. A formulation based on non-relativistic kinetic theory
for collisionless systems is adopted. Equilibrium solutions for the
kinetic distribution functions describing the initial neutral matter and
the resulting plasma state are constructed in terms of single-particle
invariants and expressed by generalized Maxwellian distributions. The
final plasma configuration is related to the initial gas distribution by
the introduction of appropriate functional constraints. Qualitative
aspects of the solution are investigated and physical properties of the
system are pointed out. In particular, the admitted functional
dependences of the fluid fields carried by the corresponding equilibrium
distributions are determined. Then, the plasma is proved to violate the
condition of quasi-neutrality, implying a net charge separation between
ions and electrons. This result is shown to be independent of the
precise realization of the plasma distribution function, while a
physical mechanism able to support a non-neutral equilibrium state is
proposed.
Authors:
Cremaschini, Claudio; Stuchlík, Zdeněk;