CRITICAL-CURRENT MEASUREMENTS AT ELECTRIC-FIELDS IN THE PV M(-1) REGIME

We describe a technique for characterising sample lengths of commercia l superconducting wire in closed loop configuration. This enables the measurement of critical current, as a function of applied magnetic fie ld, at electric field criteria in the range 10(6) to 1 pV m(-1) by det ecting the decay of current in the closed loop. How these measurements relate to the more traditional 4 terminal measurements made on short sample coils is discussed and representative data from both NbTi and N b3Sn samples are presented and analysed.