Measurement of the temperature and flow fields of the magnetically stabilized cross-flow N2 arc

Abstract

A straight, steady-state cross-flow arc is burning in an N2 wind tunnel. The arc is held in position by the balance of the Lorentz forces produced by an external magnetic field perpendicular to the arc axis and by the viscous forces of the gas flow acting on the arc column. The temperature field in the discharge is determined spectroscopically using the radiation of N I lines. Because of the lack of rotational symmetry an inversion method developed by Maldonado was used to determine the local emission coefficient from the measured integrated spectral intensity distributions across the arc in various directions. For known local temperature the mass flow field inside the arc may be evaluated from the convective term of the energy equation and the continuity equation. This is done by expanding the terms of these two equations around the point of the temperature maximum into Fourier-Taylor series and determining coefficients of the same order and power. The solution of the resulting set of algebraic equations yields the unknown coefficients of the mass flow. The flow field obtained by these calculations shows a relatively strong counterflow through the arc core. In the region for which the series expansion holds a partial structure pertaining to a closed double vortex can be recognized.