Optical measurements in an exploding wire experiment

We present optical measurements (Shadow and Schlieren pictures) of a 12.5 J oule exploding wire experiment. After performing a large number of shots so me sort of time evolution can be reconstructed from the pictures. The pictu res were taken during the dark phase (zero current) and the plasma phase. A lthough the electrical signals are quite reproducible from shot to shot (al lowing a good time correlation and indicating that the global dynamics is r eproducible) we observed that the individual details are quite different, p robably due to the non-uniformity of the wire. We observed a uniform expans ion (the volume increases almost linearly with time) with the presence of s urface instabilities and there is no evident difference in the density dist ribution between the dark and the plasma phases. Finally, we derive a mean radius and velocity evolution with time and an approximate energy balance.