 
Summary: The linear spectrum of twisted magnetic flux tubes
in viscous MHD
B. Pint'er, R. Erd'elyi and M. Goossesns
Centre for Plasma Astrophysics, K.U.Leuven,
Celestijnenlaan 200B, B3001 Heverlee, Belgium
(Received )
In the present paper we investigate the influence of tensorial viscosity on the linear MHD
spectrum for isolated twisted magnetic flux tubes surrounded by vacuum. The magnetic flux tubes
are modelled as 1D cylindrical plasma columns. Viscosity is described by its classical tensorial form
with compressive and shear viscosity. The equilibrium parameters of the flux tube are choosen to
model coronal loops.
Numerical simulations show that in ideal MHD a poloidal magnetic field can destabilize the mag
netic structure. They also show that viscosity can strongly destabilize the magnetic structure.
This destabilization depends on the poloidal component of the magnetic field.
I. INTRODUCTION
In the solar atmosphere we can observe very stable magnetic configurations, like
coronal loops, arcades, sunspots. Although magnetic confinement is possible in na
ture, it still remains impossible to achieve a stable plasma on a long timescale in
tokamaks. Recently a lot of effort has been invested in the study of the stability of
plasmas (see reviews e.g. Lifschitz 1988 , Freidberg 1987). Kerner (1989) reviewed
