The erosive efficiency of cavitating vortices is well known, although its exact mechanism has not been clarified. In order to bring fundamental information to the subject, a new device called “Cavermod” was designed in which axial collapse of a cavitating vortex is produced. We consider in this paper the design principles of the apparatus, the measurement equipment necessary for observing the phenomenon (collapse time of the order of a few milliseconds, axial collapse velocity varying between 70 and 700 m/s), and the main features of the flow. We also study the damage produced on erosion targets in order to correlate the vortex collapse with the erosion indentation features.