Stability of Second Generation HTS Pancake Coils at 4.2 K for High Heat Flux Applications

Abstract

We explored high magnetic field superconducting properties and stability at 4.2 K of Second Generation High Temperature Superconductors using both short conductors and small pancake coils. Short lengths of conductor were tested at 4.2 K and 0-25 T in parallel and perpendicular fields, demonstrating an overall critical current of 420 A/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> in a parallel field of 25 T. A 56 m length of wire was carefully characterized for performance along the length in self-field at 77 K, and in 10 m lengths at 75 K and a 0.52 T field oriented parallel and perpendicular to the face of the conductor. These characterized lengths were made into small pancake coils which were equipped with a central heater, voltage taps and taps for thermocouples. We report on the stability testing at 4.2 K of one of these coils.