Graduate School in Nonlinear Science
Sponsored by the Danish Research Academy
MIDIT OFD CATS
Modelling, Nonlinear Dynamics Optics and Fluid Dynamics Chaos and Turbulence Studies
and Irreversible Thermodynamics Risø National Laboratory Niels Bohr Institute and
Technical University of Denmark Building 128 Department of Chemistry
Building 321 P.O. Box 49 University of Copenhagen
DK-2800 Lyngby DK-4000 Roskilde DK-2100 Copenhagen Ø
Denmark Denmark Denmark
ANOMALIES OF SPATIAL PERIODICITY IN MHD TURBULENCE WITH DC CURRENTS AND
MAGNETIC FLUXES
by David C. Montgomery
Dartmouth, USA
Friday October 15, 1999, 13:00 h
Meeting Room, OFD, Building 130
Risø National Laboratory, Roskilde
Abstract: Magnetohydrodynamic turbulence theory has been pursued for 20-25
years in a "homogeneous turbulence" framework that has become standard, one
of rectangular periodic boundary conditions, incompressible flow, and
(small) scalar transport coefficients. The principal applications have been
to astrophysical plasmas: the solar wind, the solar surface, and the
interstellar medium. However, rectangular periodic symmetry precludes net dc
currents through the plasma, which become incompatible with Ampere's law.
The presence of dc currents also sometimes seems incompatible with the
(almost universal) neglect of the displacement current. Since so many
laboratory plasmas carry not only net currents but also net
externally-imposed magnetic fluxes, new approaches, stressing computation of
flux-bearing MHD behavior with realistic boundary conditions and finite
geometry, seem important to pursue.
References: David Montgomery and Jason Bates, Phys. Plasmas 6, 2727 (1999);
also David Montgomery and Xiaowen Shan, "Magnetohydrodynamic Turbulence with
Net Currents," in "Small-Scae Structure in Three-Dimensional Hydrodynamic
and Magnetohydrodynamic Turbulence," ed. by M. Meneguzzi et al (Berlin:
Springer-Verlag 1995). pp. 241-254.