Wires made of materials having high boiling points were exploded in an evacuated vessel of coaxial design. It was found that the influence of the radial electric field on the x‐ray emission as well as on the initiation of the shunting discharge was small. In addition, the shunting discharge and the vaporization of the wires were studied by a Kerr‐cell camera. Tungsten and molybdenum wires were found to vaporize in a nonuniform way. A model to explain this behavior is suggested.