We report on the spark plasma synthesis, sintering and characterization of bulk MgB2 superconductors prepared according to three processing routes using non conventional Spark Plasma Sintering (SPS):     i) sintering of a commercially available MgB2 powder,    ii) in-situ synthesis followed by sintering of a mixture of magnesium and nano-boron powder (Mg+2B),   iii) sintering of a mixture of Mg and MgB4 powder. The density of the obtained bulks was up to 98 % of the theoretical density of the material. The highest critical current densities at 20K in self-field and 1 T were equal to 549 kA/cm2 and 360 kA/cm2, respectively, and were obtained with the MgB2 sample processed according to the Mg+2B route. The structural characterization and chemical analysis were carried out as well as the superconducting properties. In addition, we investigated the magnetic levitation force and the magnetic flux mapping for the homogeneous current distribution in the whole sample.

Keywords: MgB2, Spark Plasma Sintering, Density, Critical current density, Jc