Field dependence of the critical current density of MgB2 conductors between 4.2 K and 30 K up to 20 T

Abstract

The critical current density (J(c)) of the monofilament Monel/Fe/MgB2 wire was measured between 4.2 K and 30 K with a Variable Temperature Insert (VTI) in a 20 T superconducting magnet using the analog DC pulse four-wire method with 1 mu v/cm criterion. The critical current density, J(c) was measured to be 0.16 x 10(5) A/cm(2) at 4 T at 21 K for a MgB2 sample which was annealed at 700 degrees C for 5 min and at 900 degrees C for 5 min under Ar gas flow. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) analysis were used to characterize the microstructure of the samples.