ENHANCEMENT OF THE CRITICAL CURRENT AND TRAPPED MAGNETIC FIELD PROPERTIES OF THE PARTIAL DOPED AND SINTERED MgTi0.06B2 BULK SUPERCONDUCTOR USING NUMERICAL AND EXPERIMENTAL METHODS

Between the intermetallic superconductors, MgB2 superconductor has superior properties, as the high critical temperature (Tc), critical current density (Jc), stable levitation force. The magnetic field trapping property of this superconductor makes these materials very promising candidates for technological applications, such as the next generation of medical MRI devices and super-magnets for Maglev systems. The trapped magnetic field Btrap on the sample axis of a MgB2 superconductor, due to an induced persistent supercurrent, depends on the critical current density Jc, the sample diameter R and geometrical constant (or Levitation force FL depends the shielding current density Jc, the critical current loop radius r, the sample geometry, sample volume and external magnetic field gradient) [1,2]. The studies, on the increasing of the trapped field value in literature, reported that the critical current density value decreases while going to the outer sample region [3] and the trapped magnetic field increases initially with increasing sample diameter but it gets saturation for the larger diameters [1]. In our previous study, on electromagnetic modelling of regional critical current and bulk trapped field, we determined that the tendency to saturation in the peak trapped field pointed out that the increasing of the bulk diameter alone does not have a significant effect on the value of the trapped magnetic field, unless the bulk superconducting current density was improved uniformly throughout the whole MgB2 bulk [4]. Addition to the trapped magnetic modelling and the nanoparticle Ag doping (using the regional doping method) [2], in this study, we performed the Infrared (IR) line laser process on sample surface acted as a second sintering to further enhance the supercurrent density distribution uniformly of the bulk MgTi0.06B2 superconductor and so to increase the maximum trapped magnetic field value. After the laser treatment at 28 K it is seen that, the Jc improved both inner and outer sections for undoped Ag0 and doped Ag3 sample. Also the maximum Jc value increasing approximately two times for the inner region Ag3 (1) specimen and 1.2 times for the outer region Ag3 (2) specimen explains that the fast laser sintering process is much more effective at the non Ag added surface regions.