Determination of the MHD channel parameters for improving the homogeneity of electric current

Abstract

The problem of electric current flow in a conductor enclosed in a channel of arbitrary conductivity is solved numerically to estimate the conditions for obtaining a homogeneous electric field. The length of the section at which the value of the radial component of the electric current density does not exceed 1% of the maximum along the channel axis was chosen as a numerical criterion for the homogeneity of the flow. We detected the nonlinear character of the dependence of the length of the section of homogeneous current flow on the aspect ratio of the channel and on the wall thickness. By increasing the channel length at a fixed diameter, it is possible to achieve uniform current flow along more than 80% of the channel length with an aspect ratio greater than 10. The dependence of the length of the homogeneous spreading section on wall thick-ness has a local extremum at wall thickness less than 0.4 of the pipe radius. Depending on the ratio of conductivities of the wall and the medium, the extreme point can be either a local minimum (a well conducting wall) or a local maximum (a poorly conducting wall). The dependence of the length of the section of homogeneous current flow on the length of current conduits is linear, but the slope is determined by the ratio of conductivities of the medium and the wall.