Superconducting magnet for the PETRA electron- positron accelerator at the DESY particle physics laboratory, Hamburg. The magnet contains coils made of superconducting niobium wire. A superconductor is a material that allows an electric current to flow with almost no resistance, providing it is used at an extremely low temperature - typically a few degrees above absolute zero, -273 degrees Celsius. Advantages of superconducting magnets over conventional types include higher achievable magnetic fields with lower power consumption.