Deviation of Magnetic Annular Shock-Tube Operation from One-Dimensional Model

In a magnetic annular shock tube the gas is pushed axially by an azimuthal magnetic field. Since this field varies inversely as the radius, there are radial nonuniformities in the resulting flow which are analyzed for small values of the ratio ε of annulus spacing to radius. The pressure variation across the annulus at the interface between plasma and driving field results in a tilting of the interface. This flow is analogous to the flow resulting from a dam break in shallow-water theory; it is characterized by a wave of speed (εp/ρ)½. The maximum value of ε for which the interface and shock wave remain separated is calculated. Nonuniformities are also produced at the shock front when an azimuthal magnetic field is present ahead of the shock; the shock becomes nonplanar and radial variations in the flow persist far behind the shock. For some cases these nonuniformities are appreciable even for values of ε so small that the interface and shock wave remain separated.