TABLE OF CONTENTS Bruce L. Freeman and Andreas A. Neuber
The environment within the cavity of a flux compression generator is hostile to insulators and insulating gases. In particular, the shock driven through the armature and into this gas is sufficient to provide significant heating. However, the reflected shocks between the armature and the stator as the armature approaches contact with the stator can severely heat the gas or simply ionize it. With this in mind, a set of experiments was designed to simulate the environment within an FCG and to measure the electrical conductivity of various gases in this environment. Improved electrical conductivity data for gases, particularly sulfur hexafluoride and air, under conditions found within FCG's, may facilitate better FCG modeling and design. These tests provide data toward quantifying the considerations of using SF 6 versus air as the fill gas within an FCG.
A cylindrical FCG with the dimensions listed in Fig. 5.1 was used as the model for the shock tube design. The Gurney method was used to determine the armature expansion velocity and angle. This result was translated to a relative velocity at which the armature approached the stator. The armature angle was calculated to approach the stator at a relative velocity of 3.1 km/s at an angle of 22.6 using the Gurney equations for a cylinder [Ken97]. We note that this value is of the same magnitude as a typical armature...
