Actas de congresos
Equilibrium topology for plasmas with reversed current density.
Fecha
2013-07-01Registro en:
EPS Conference on Plasma Physics, 40th, 2013, Finlândia.
Autor
Taborda, David Ciro
Caldas, Ibere Luiz
Institución
Resumen
Actually, transition from positive to negative plasma current and quasi-steady-state alternated
current (AC) operation have been achieved experimentally without loss of ionization. The
large transition times suggest the use of MHD equilibrium to model the intermediate magnetic
field configurations for corresponding current density reversals. In the present work we
show, by means of Maxwell equations, that the most robust equilibrium for any axisymmetric
configuration with reversed current density requires the existence of several nonested families
of magnetic surfaces inside the plasma. We also show that the currents inside the nonested
families satisfy additive rules restricting the geometry and sizes of the axisymmetric magnetic
islands; this is done without restricting the equilibrium through arbitrary functions. Finally,
we introduce a local successive approximations method to describe the equilibrium about an
arbitrary reversed current density minimum and, consequently, the transition between different
nonested topologies is understood in terms of the eccentricity of the toroidal current density
level sets.