Normal zone propagation in a YBCO superconducting tape:measurement and analysis of quasi-adiabatic normal zone propagation in a YBCO coated conductor

In this report the measured normal zone propagation velocity and minimal quench energy of YBCO coated conductor tapes are presented throughout a wide range of temperature, of the percentage of the critical current and applied magnetic �eld. For these measurements a pre-existing set-up is reassembled and improved. Surprisingly the measured data show that the normal zone propagation velocity depends predominantly on the current and hardly on temperature or applied magnetic �eld. The minimal quench energy, on the other hand, depends on all three external parameters. The measured data are then compared to analytical and numerical descriptions for the normal zone propagation and the minimal quench energy. This leads to the introduction of a cooling term into the analytical and numerical models to �nd a better agreement between the data and the model predictions. This means that the experiment is only quasi-adiabatic, as opposed to fully adiabatic. For the minimal quench energy, signi�cant di�erences between the experiment and the models are found. These di�erences are explained by the relatively slow heat transfer between the heater and the tape, which causes only a fraction of the energy to be transferred, when the normal zone already develops.