### Abstract:

In High-T<sub>c</sub> superconductors there are suggestions of a non-nzero density of quasi-particle states in the energy gap. Thermally activated normal excitations can be reconverted into ground state superfluid Cooper pairs for temperatures below the critical transition temperature (T<sub>c</sub>). The core excitations of a vortex and the quasi-particle density inherent in High-T<sub>c</sub> superconductors describe the localised and extended states, respectively, that contribute to the distinct dissipative processes. In the most frequently applied geometries, the behaviour of the two different processes cannot be separated as they both have similar linear dependencies on current and applied magnetic field. A disc shaped sample of sintered YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub>, high - T<sub>c</sub> superconductor, was used to investigate circular flux flow and inductive voltages due to a Lorentz force, (J x B). The dissipation due to a flow of quasi-particles is detected as a radial potential drop. The circulating vortices also produce a voltage drop for the disc geometry. The induced voltage observed, is assumed to be the sum of two terms, α<sub>q</sub>W<sub>n</sub> and W<sub>φ</sub>, where they represent the quasi-particle and flux motion induced parts, respectively. The portion of the quasi-particle contribution to the dissipation is represented by the dependence of α<sub>q</sub>≡α<sub>q</sub>(T,J,B). Alternatively, α<sub>q</sub> can be regarded as a normalization �f the dissipation through the critical temperature region when all contributions from circulating vortices have been accounted for. The second term, Wφ, is proposed to consist of a quadratic radial dependence and the induced part, T<sub>φ</sub>, due to the circulating vortices. The temperature dependence of T<sub>φ</sub> is plotted for each of the specific magnetic fields and current densities used. T<sub>φ</sub> is shown to consist of a T<sub>o</sub> term representing the rate at which circulating vortices cut a surface described by the above quadratic dependence. From the experimental observations it can be concluded that dissipation due to quasi-particle motion is the major factor contributing to transport properties of a "123" ceramic High-T<sub>c</sub>. T<sub>φ</sub> is analyzed in terms of the Thermally Activated Flux Flow model (TAFF), T<sub>φ</sub> = T<sub>o</sub>U(T,B)/T exp[-U(T,B)/T], to extract the activation energies for each current/magnetic field consideration. The values found for the term, U(T,B) are consistent for all the different current and magnetic field combinations. The sample design provides for a non-uniform current density in the radial direction, which causes an intrinsic proximity boundary as the centre of the disc is driven 'normal' (at fixed T and B) before the rest of the sample. These intrinsic weak links caused by the oxygen stoichiometry of the particular sample, impede the path of circular motion of the vortices. With regard to this proximity effect, the TAFF is influenced and the activation energies have a temperature and magnetic field dependence of the form, U(T,B) = U<sub>o</sub>exp(-B/B<sub>o</sub>) . (l-t<sup>2</sup>)<sup3/2</sup>. The values found for U<sub>o</sub>≈0.15 eV and B<sub>o</sub>≈4.2T are comparable to reported data for these parameters.