Fabrication of Chemically Doped, High Upper Critical Field Magnesium Diboride Superconducting Wires

75187-Controlled chemical doping of magnesium diboride (MgB2) has been shown to substantially improve its superconducting properties to the levels required for high magnetic field applications, such as needed for fusion energy. However, the doping is difficult to accomplish through the usual route of solid state reaction and diffusion. Further, superconducting cables of MgB2 are difficult to fabricate because of the friable nature of the material. This project will develop technology for the co-deposition of boron and dopants using chemical vapor deposition, leading to the production of long continuous lengths (> 1 km) of optimally doped boron filament. Bundles of large numbers of these filaments will be pressure cast in a magnesium matrix and subsequently converted to MgB2 to form a continuous composite cable. In Phase I, established commercial processes for depositing continuous boron filament will be modified to produce 1-10% doping with titanium and carbon while maintaining the ability to handle the filaments. Multiple lengths of these doped filaments will be pressure cast in magnesium and converted to MgB2. The mechanical and superconducting properties of these composites will be characterized. Commercial Applications and Other Benefits as described by the awardee: Chemically doped, MgB2 superconducting magnets should perform at least as well as NbTi and NbSn3 in high magnetic fields while offering improvement in terms of operating temperature. These characteristics should make doped MgB2 an effective material for high magnetic field applications, such as magnetic confined fusion, medical MRI devices, and electric industry power devices.