Abstract
We have fabricated a small test coil with an AlN former by employing Cu-Ni sheathed Ta barrier MgB2 multifilamentary wire made in a wind-and-react process. An overcurrent was applied to the coil conduction-cooled in an initial temperature range between 10 K and 30 K to investigate its thermal stability by measuring the temperature distribution in the winding and the terminal voltage after application of the overcurrent. The experimental results show that the permissive temperature rise without thermal runaway decreases with the initial temperature, while total heat generation at the time of thermal runaway is at a maximum when the initial temperature is approximately 14 K. We also numerically calculated the responses of the test coil to the overcurrent by simulating the electrical and thermal processes using the finite element method and V-I characteristics of the coil. The comparisons with the experimental results show that the electrical and thermal responses are reproduced well using the numerical model.
