The management of data access is facilitated. During the cool-down period, the beam successively scans two rows separated by about half the wafer diameter, and travels back and then forth across the distance between the two rows, while the radiation beam source continuously generates the beam. A shielding gas mixture prepared this way is outstandingly suited, especially because of the helium content, for arc welding of aluminum and aluminum alloys. The flexible portion may include an inner portion that includes an electrical conductor and an outer portion that includes a transparent or translucent material.