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This article examines how major types of scientific facilities, namely synchrotrons, and the research they enable, are diffused through a dialectic between the international and national levels. This circulation is particularly marked by the transition from one generation of facility to another. Synchrotrons illustrate an internationalization model that is neither that of the concentration of research in one single device in the world, nor that of a device that adapts to multiple uses due to the activities of communities at the interstices of science, technology, industry and politics, but that of facilities that multiply through the gradual attraction of new user communities. Scientists encourage this development by working between the national and international levels, to the point where the difficulties of international cooperation, such as communication problems, isolation, and conflicts between representatives of different nationalities, are erased.