High speed plasma flow about probes

A method for evaluation of the interaction between a uniform magnetic field and a compressible inviscid, electrically conducting ideal gas flow past a blunt body is presented. An experiment using a double diaphragm shock tube to produce a slug of gas with high electrical conductivity is performed to confirm the theoretical results. The theoretical problem is considered in two parts. Firstly, the flow field around a hemispherical cap in a supersonic flow is evaluated using the method of integral relations. The difficulty associated with the mathematical saddle point singularity in this scheme is seen to be the instability of the integral solution curves to small perturbations. This sensitivity is used to advantage by applying small parameter perturbations to extend the integral curves near the singularity, an innovation due to South [1969] . In this way, the extrapolation error across the sonic line is decreased while at the same time the computational effort expended in determining the integral curve is reduced. Secondly, the solution for the perturbed magnetic field is obtained using the Biot-Savart relation and solution of the resulting integral equations. The advantage of this approach, for problems in which the boundary conditions are asymptotic to the undisturbed values at infinity, lies in the simple way in which these conditions are satisfied. The problem is reduced to the solution of a Fredholm integral equation and this is solved numerically. The large magnetic Reynolds number limit to the application of this method is determined. The analysis is applied to the determination of the induced magnetic field near the nose of a magnetic probe in a supersonic stream with an applied uniform magnetic field. The magnetic flux density measured by the probe is significantly reduced when the magnetic Reynolds number is greater than unity. The experimental results show reasonable agreement with the predicted values and differences are explained in terms of the short test gas duration and the assumption of ideal gas behaviour for the theoretical computations.

Author dc:creator

• Allen, Gregory Hamilton

Language dc:language.iso

en

Dc Identifier Other

b1016354

OAI identifier oai:identifier

oai:openresearch-repository.anu.edu.au:1885/137197