Abstract
This thesis is an investigation of the internal dynamics of accelerated arc plasmas including instabilities of the Kruskal-Schwarzchild type. The accelerated arc plasmas are in the regime of plasma armatures typical in electromagnetic rail launchers with current densities of the order of 10$\sp8$ amps/meter$\sp2$, accelerations of the order of 10$\sp7$ meters/sec$\sp2$ and temperatures of the order of 10$\sp4$Kelvin. A numerical 2 dimensional MHD model is used to study the plasma armature in contact with a near vacuum magnetic field. The nonlinear bubble, spike and other surface deformations are followed using a hybrid flux corrected transport (FCT) code. A description of the resulting disruption of the main plasma arc is sought. This disruption together with rail ablation can lead to secondary arcs and other loss mechanisms.