Messungen der radialen Verteilungen von elektrischer Stromdichte und Temperatur im Wasserstofflichtbogen mit axialem Magnetfeld

Abstract

Abstract The radial distribution of the axial electric current density in a stationary hydrogen arc with axial magnetic field was measured. This was done by shooting small induction coil probes across the arc. The experiments confirmed that the arc current is almost completely restricted to the magnetic flux tube defined by the cathode radius, as discussed in a previous paper. In the case of a hollow anode a distinctly tube-like current density distribution was found. With the aid of the axial electric field measurements already presented temperature profiles in good agreement with other experimental methods were derived. In addition, the ohmic heat input into the arc could be determined. This is much larger than the energy that can be lost radially as a result of thermal conduction according to the measured temperature profile and the thermal conductivity known from the theory. The cause may be the Rayleigh-Taylor instabilities which were observed or radial mass flows directed outwards. Allowing for even relatively slow flows (υr ˂ 104 cm/sec) in the calculations one obtains good agreement with the measured distributions.