AC SUSCEPTIBILITY RESPONSE OF BULK YBCO SUPERCONDUCTORS IN THE PRESENCE OF A TEMPERATURE-GRADIENT

Low-frequency ac susceptibility measurements on ceramic YBCO supercond uctors carried out at the presence of a quasi-one-dimensional temperat ure gradient are compared with those made without the temperature grad ient. The values of the different characteristic temperatures measured on samples without and with a temperature gradient are identical but in the second case itch characteristic temperature is a medium value. When the temperature gradient is constant on the sample the arithmetic medium value of the local temperatures is the effective characteristi c temperature different phenomena.