[en] Bulk and tape specimens of Nb₃Al have been fabricated by the powder metallurgy method between Nb₂Al and Nb. The microstructure and superconducting properties on the starting materials and the temperature of a heat treatment have been studied. X-ray diffraction analysis was carried out in order to identify the phases formed by the heat treatment. The A15 single phase, Nb₃Al, were formed at 1100degC for the bulk specimen prepared from the Nb₂Al/Nb mixed powders. The temperature of a heat treatment formed the A15 single phase prepared from the Nb₂Al/Nb was down 100-200degC in comparison to that prepared from the Nb/Al mixed powders. The highest critical temperature, Tc, obtained in the bulk specimens prepared from the Nb₂Al/Nb mixed powders is 16.0 K. (author)

[en] Two dimensional electrostatic particle simulation is implemented to study potential formation in the system including the magnetic filter and the plasma grid. In the case of uniform density and temperature profile, the plasma grid can not locally control the plasma potential. In the case of nonuniform profile in which the magnetic filter separates the plasma into high density and high temperature (source plasma) and low density and low temperature (diffused plasma) regions, plasma potential is high in the source plasma region and low in the diffused plasma region. It is possible that plasma potential in the diffused plasma is locally controlled by changing plasma grid potential. (author)