Interchange instability in finite conductivity accelerated plasma arcs

A first-order perturbation expansion of the magnetohydrodynamic equations is used to study the growth of Rayleigh-Taylor or interchange instability in accelerated plasma arcs. The mode equation is fourth order due to the inclusion of finite conductivity. It is solved numerically to yield results that are an improvement over previous work. The growth rates are less than in the infinite conductivity model. As in previous work the growth rates in typical rail launcher situations are large enough to permit full development of the instability