G. Z. Li, M. D. Sumption, M. A. Susner, Y. Yang, M. Kongara, M. A. Rindfleisch, M. J. Tomsic, C. J. Thong, E. W. Collings
Recent advances in MgB2 conductors are leading to a new level of performance. Based on the use of proper powders, proper chemistry, and an architecture which incorporates internal Mg diffusion (IMD), a dense MgB2 structure with not only a high critical current density Jc, but also a high engineering critical current density, Je, can be obtained. Such a conductor could be described as a second generation MgB2 conductor. In this paper, a series of these new second generation (2G) conductors has been prepared. Scanning electron microscopy and associated energy dispersive X-ray spectroscopy were applied to characterize the microstructure and composition of the wires, and a dense MgB2 layer structure was observed. The best layer Jc for our sample is 1.07x10^5 A/cm^2 at 10 T, 4.2 K, and our best Je is seen to be 1.67x10^4 A/cm^2 at 10 T, 4.2 K. Optimization of the transport properties of these 2G wires is discussed in terms of B-powder choice, area fraction, and the MgB2 layer growth mechanism.
View original:
http://arxiv.org/abs/1206.3550
No comments:
Post a Comment