Minimum quench energy measurement for superconducting wires

We have developed a new method of measuring minimum quench energy (MQE) of superconducting wire. There have been conventional methods using heating wires, whose diameters are /spl sim/0.1 mm and are glued by epoxy resin. When we induce a pulse heat to superconducting wires, a duration of the pulse must be several hundreds micro seconds to demonstrate actual disturbances (for instance wire motion) in a superconducting magnet. In spite of this fact, thermal diffusion time constants of the conventional heaters are larger than the duration of the actual disturbance, because of these electrical insulator of the heating wire and the epoxy bind. Therefore, this kind of heater is not able to demonstrate the actual disturbance. To solve this problem, we have proposed a new constitution of a heater. In our method, heat generation is introduced in high resistive layer on a surface of a superconducting wire. The high resistive layer is consist of carbon paste. The thickness of the carbon paste layer is /spl sim/20 /spl mu/m, thus a time constant of this heater is expected to be small enough to demonstrate the actual disturbance. Adopting our new method to our MQE measurement, we successfully evaluate MQE of superconducting wires with high precision. Several results are introduced in this paper.