Processing of Bi-2212 high temperature superconducting wires

Bi-2212 high temperature superconductors can be used for producing very high magnetic fields. They are studied at CERN for potential use in accelerator magnets. The powder-in-tube wires are produced by inserting Bi 2212 particles into a Ag matrix. In order to transport high supercurrents the Bi 2212 needs to be melted during a processing heat treatment in a process gas containing oxygen. For the processing of Bi-2212 wires a 100 bar overpressure furnace has been designed at CERN. The first part of this thesis describes the setting up of a high pressure gas supply system and its installation. To ensure the safe operation of the overpressure furnace the high pressure reaction cell has been pressure tested up to 250 bar. A LabVIEW program was developed in order to control the pressure during the heat treatment and to record the furnace temperature. The oxygen partial pressure in the process gas influences the phase sequence and the Bi-2212 melting temperature. The phase changes during the processing of Bi-2212 wires at different oxygen partial pressures have been studied by means of in situ synchrotron X-ray diffraction experiments, performed at the high energy scattering beamline ID15B at the European Synchrotron.