MgB2 wires with Ti and NbTi barrier made by IMD process

Abstract

MgB2 wires with Ti and NbTi barriers have been made by internal magnesium diffusion (IMD) into boron process. Critical currents, strain tolerances and AC loss of wires with Ti and NbTi barriers have been compared. It was shown that worse uniformity of NbTi barrier affects the creation of regular MgB2 layer and consequently influences (reduces) also the current densities. Positive effects of NbTi barrier are in improved strain tolerance and reduced coupling losses. The maximum AC loss of not twisted wire with Ti barrier is measured at frequency 9Hz, but it is shifted up to 60Hz for NbTi due to considerably increased barrier resistance at 20K.