Transport of Poloidal Magnetic Flux Along a Flux Rope in Stratified Solar Subphotospheric Regions

James Chen and Joseph Huba

Plasm Physics Division
Naval Research Laboratory
Washington, DC 20375

A three-dimensional (3D) MHD simulation model of vertical, cylindrical
magnetic flux rope embedded in a stratified background plasma has been
constructed.  The initial flux rope consists of a current channel of
finite radius and is in non-force-free equilibrium with pressure and
constant downward gravity.  The poloidal magnetic field is increased
in time at the base of the simulation region.  The focus of the study
is to understand the resulting plasma dynamics inside and outside the
current channel, corresponding to relatively low-beta and high-beta
regions, respectively.  The role of magnetic reconnection in the
evolution of the system is discussed.  Fluctuations in density are
imposed, and a horizontal flow from the side boundary is allowed.  The
poloidal flux injected from the base propagates outward and upward,
developing highly incoherent structures due to both gravitational
effects and the imposed noise.  For comparison, similar simulations
are carried out for the Gold-Hoyle flux rope.  Possible observable
manifestations of the transport of poloidal flux through the
photosphere are discussed.

Work supported by ONR