4MF09 1 Abstract—The direct observation of the field at the surface of SC samples when the field is applied or in the remanent state, allows the observation of the current distribution along the magnetization loop by using inverse problem solvers. Furthermore, the mean value of the field reflects well the magnetization of the sample obtaining the magnetization loop taken in account both possibilities, the In Field Hall Mapping technique, thus, has revealed as a powerful characterization technique. This technique can be improved by including the critical state simulation, giving so a very complete way to characterize artificially welded superconducting samples, thus allowing the identification of the critical current flowing through the surface between domains as is the case of the effect of welded bulks. Some examples of the characterization procedures are reported. Index Terms—superconductors characterization, magnetic remanence currents, superconducting welding. I. INTRODUCTION HE great effort devoted to the realization of superconducting welding between ceramic pellets of YBCO has impulsed the development of fast, easy, non destructive and efficient techniques to determine the quality of them. Several techniques have been proposed to watch the quality, but the non destructive requirement restricts them to magnetic testing. Essentially, there are two ways to obtain information about the currents induced in the superconducting sample after a magnetic field is applied, determining so which current is trespassing the superconducting joint, the intergrain Manuscript received October 5, 2004. This work was supported in part by the TMR U.E Contract HPRN-CT-2000-0036 ERBFMRXCT “Supermachines”.. X. Granados is with the ICMAB-CSIC, Campus UAB, 08193 Bellaterra, Spain (e-mail: granados@icmab.es). B. Bozzo is with the ICMAB-CSIC, Campus UAB, 08193 Bellaterra, Spain (e-mail: bozzo@icmab.es). S. Iliescu is with the ICMAB-CSIC, Campus UAB, 08193 Bellaterra, Spain (e-mail: iliescu@icmab.es ). T. Puig is with the ICMAB-CSIC, Campus UAB, 08193 Bellaterra, Spain (e-mail: teresa.puig@icmab.es ). X. Obradors is with the ICMAB-CSIC, Campus UAB, 08193 Bellaterra, Spain (e-mail: obradors@icmab.es ). J. Amorós is with the Department of Applied Mathematics of the UPC, Diagonal.647, 08028 Barcelona, Spain (e-mail: jaume.amoros@upc.es ). M. Carrera is with the Department of Medi Ambient I Ciències del sòl of the U de L, Jaume II 69, 25001 Lleida, Spain (e-mail: mcarrera@udl.es). current, and the current which is flowing inside the grain, the intragrain current. One way is just to determine the magnetization from integral magnetic measurements done, habitually, in magnetometers. The other way is to observe the local value of the magnetic contribution of the sample during or after the application of an external magnetic field. This last proposal has been strongly developed along the last years by using magneto-optic microscopy or by obtaining the values of the normal field point by point by rastering a Hall probe. In any case, both techniques require the support of an Inverse Problem Solver to obtain the map of currents corresponding to the measured magnetic field map. Although magneto-optic techniques are more powerful and faster than Hall Scanning Magnetometry, the fact of its non linear behavior reduces the field of application to middle field situation just in the range from some Gauss up to hundreds of Gauss, after a calibration of the system. On the other hand, Hall magnetomery shows very good linearity from tenths of Gauss up to several Tesla. The most relevant counterpart of the Hall Scanning Magnetometry could be the speed of the measurements. Both local techniques have appeared powerful tools to understand the current distribution generated in a magnetization process and to qualify the effect of local inhomogeneties over the superconducting critical current along magnetization processes. In this work we study the quality of the welds that we have performed between YBCO blocks by using silver to induce the local fusion [1]. Our characterization method has been developed from the simulation of the current distribution, which can be deduced from the direct application of the Bean model for critical state, in the case of the non homogeneity generated for a weld, and we contrast these results from those obtained the “Caragol” Inverse Problem Solver [2], [3] to the magnetization map, measured by In Field Hall Mapping technique [4], [5] at the remanence state. II. EXPERIMENTAL A. Samples Standard single domain pellets of YBCO have been cut out in order to perform 10x10x5 cm 3 parallelepipedic blocks. Each one has been also cut in order to obtain two 10x5x5 cm 3 Critical current determination of artificially welded HTS samples by In field Hall Mapping Technique X. Granados, B. Bozzo, S. Iliescu, E. Bartolomé, T. Puig, X. Obradors, J. Amorós and M.Carrera. T