SBIR-STTR Award

Improved superconducting wire technologies are needed for the magnets that support high-energy-physics research accelerators. Controlled chemical doping of magnesium diboride (MgB2) has been shown to substantially improve superconducting properties to the levels required for high field magnets, but consistent dopant concentrations and homogeneity are difficult to accomplish through the usual route of solid state reaction and diffusion. Furthermore, a high quality source of doped boron must be established before the commercialization of MgB2 superconductors becomes viable. This project will investigate the gas-phase plasma synthesis of boron powder, in which dopants and boron are atomically mixed in the plasma, to produce nano-sized batches of doped boron powder. In Phase I, boron powder doped with carbon, titanium, and silicon carbide will be converted to MgB2 superconducting pellets and powder-in-tube wires, and the superconducting properties will be measured. The effect of powder particle size, purity, dopant concentration, and chemical homogeneity on the superconducting properties of MgB2 will be systemmatically investigated.

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 field magnetic fields and still offer an improvement over the latter in terms of operating temperature. These characteristics would make doped MgB2 an effective material for high-magnetic-field applications, such as particle accelerators, confined fusion, electric industry devices, and medical MRI devices. Cheaper and more efficient medical MRI devices could lower examination costs, find potential health problems earlier, and thus benefit society as a whole

Controlled chemical doping of magnesium diboride (MgB2) has been shown to substantially improve superconducting properties to the levels required for high field magnets. However, consistent dopant concentrations and homogeneity are difficult to accomplish through the usual route of solid state reaction and diffusion. Furthermore, a high quality source of doped boron needs to be established to advance the state of the art and to ultimately commercialize MgB2 superconductors. This project will prepare carbon-doped boron powders suitable for the fabrication of high performance MgB2 conductors. In Phase I, a gas-phase plasma synthesis method was investigated for producing doped-boron nanopowders suitable for use in commercially viable MgB2 superconductor wire. Boron powder, doped with carbon and titanium, was converted to MgB2 superconducting pellets and multifilament powder-in-tube (PIT) wires, and superconducting properties were measured. The effect of certain parameters (such as dopant level, powder particle size, and wire processing temperature) on the superconducting properties was determined. The carbon-doped MgB2 was fabricated into 19-filament wires and yielded an upper critical magnetic field of 37T, equal to the highest values yet attained for bulk MgB2 materials. In Phase II, carbon, titanium, and silicon carbide will be investigated as dopants and optimum compositions will be defined. The effect of powder particle size, purity, dopant concentration, and chemical homogeneity on the superconducting properties of MgB2 will be determined. Fundamental plasma processing parameters for the optimal synthesis of the boron nanopowders will be developed.

Commercial Applications and Other Benefits as described by the awardee:
Chemically doped MgB2 superconducting magnets should perform at least as well as NbTi and Nb3Sn in high field magnetic fields, with an improvement in terms of operating temperature. MgB2 should thus become an effective material for high magnetic field applications, such as for particle accelerators, confined fusion, and medical MRI devices. Cheaper and more efficient medical MRI devices could lower examination costs and detect potential health problems earlier