  Three-dimensional, time-dependent numerical simulations of the dynamics of
magnetic flux ropes are presented. The simulations are targeted towards an
experiment previously conducted at CalTech (Bellan, P. M. and J. F. Hansen,
Phys. Plasmas, 5, 1991 (1998)) which aimed at simulating Solar prominence
eruptions in the laboratory. The plasma dynamics is described by ideal MHD
using different models for the evolution of the mass density. Key features of
the reported experimental observations like pinching of the current loop, its
expansion and distortion into helical shape are reproduced in the numerical
simulations. Details of the final structure depend on the choice of a specific
model for the mass density.
