We have studied the effect of Zr addition on the field dependence of transport J c for filamentary (Nd Eu Gd)Ba 2 Cu 3 O x superconductors to enhance the flux pinning. We prepared the filamentary (Nd 0 33 Eu 0 38 Gd 0 28 )Ba 2 Cu 3 O x Zr y (y = 0, 0.001, 0.002) precursors by a solution spinning method. The precursor was partially melted in flowing 0 1%O 2 + Ar under various heating conditions to obtain high J c value. The optimum heating condition was dependent on sample diameter. A maximum J c value of 3 10 4 A cm 2 at 77 K and self-field was attained for the sample with 0.001 at% Zr. The samples had well aligned texture along the filament diameter as well as the length. The J c was measured at 77 K in applied magnetic fields up to 14 T by rotating the sample along the direction perpendicular to the filament length. Anisotropic behavior of the field dependence of J c was detected. Although the J c values measured at the optimum angle for the samples with 0.001 at% Zr decreased with increasing the applied fields above 10 T, the J c values for the Zr addition samples were higher than that for the non addition sample by applying the fields up to 11 T.

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A visualization and a quantification technique of a latent electric charge image on a dielectric material have been developed by using Pockels effect and a computer image processing technique. The Pockels cell of a BSO (Bi,2SiO20) single crystal was used as a transducer to transfer the surface charge density to retardation of transmitted light beam. In order to reduce a spatial noise of light beam, an optical phase modulation technique and a computer image lock-in amplifier processing were used. The measurement system has several improved performances ; the sensitivity of surface charge of 1 nC/cm2, the spatial resolution of 200 um and discrimination of the charge polarity. The basic principle of advanced electrooptic surface charge measurement is described and the typical surface charge distribution of positive discharge streamer produced by an impulse high voltage (5 kVpeak) is demonstrated. The measured surface charge images are shown on a color computer monitor as pseudo color in three-dimensional beautiful figures.

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