METHOD AND APPARATUS FOR DETERMINING THE NATURE OF A MATERIAL IN A CAVITY BETWEEN ONE INNER METAL WALL AND ONE OUTER METAL WALL

摘要

The invention relates to a method and apparatus for determining the nature of a material in a cavity between one inner metal wall and one outer metal wall provided outside the inner metal wall. First a tool is located on the inside of the inner metal wall, where the tool comprises a pulse generator and a signal recorder. An electromagnetic short duration pulse is generated by means of the pulse generator, the pulse inducing mechanical vibrations in the walls. Data representing the reflections of the mechanical vibrations from said cavity is recorded by means of the signal recorder. The recorded data is analyzed to determine the nature of the material in the cavity.