Plasma Torch Synthesis of Homogeneous C-alloyed MgB2 for High-Field Applications

MgB2 is proving to be a very promising superconductor. Until recently, the low critical field of pure MgB2 had inhibited its use for higher-field applications, such as for high energy physics experiments. Yet, recent advances have demonstrated a dramatic enhancement of the upper critical field (Hc2) when MgB2 is doped with C or SiC. However, in all cases, the resulting material typically has demonstrated poor control of stoichiometry, homogeneity, and porosity. This project will develop a plasma reactor for preparing micron-scale particles of C-doped MgB2 on seed cores of B4C. Plume conditions will be controlled, so that C-doped MgB2 is formed with uniform stoichiometry and small grain size. Phase I will build an aerosol dispersion system and modify a commercial radio frequency (RF) plasma gun to support the aerosol powder flow and extended exit plume. In Phase II, the system will be used to synthesize C-doped MgB2, and a systematic optimization of process parameters will be conducted. Commercial Applications and other Benefits as described by the awardee: A C-alloyed MgB2, with less porosity and better homogeneity, should result in a superconductor with dramatically better performance. It should be possible to manufacture wire with a cost that is less than NbTi, improving the cost-effectiveness of superconductivity for a wide variety of applications.