STUDY OF THE EFFECT OF TRANSPORT CURRENT AND COMBINED TRANSVERSE AND LONGITUDINAL FIELDS ON THE AC LOSS IN NET PROTOTYPE CONDUCTORS

AC losses in cables carrying dc as well as ac transport currents at different dc background fields up to 2T have been measured on three types of Nb3Sn subcables in a new test facility. In this facility it is possible to apply sinusoidal transverse ac fields up to dB/dt=5T/s and longitudinal ac fields up to dB/dt=30T/s separately and simultaneously. The ac loss is measured with a calorimetric method. Simultaneously applied transverse and longitudinal fields can result in a loss which exceeds the added contributions of the separate applied ac fields. Within the measured range it is about correct (within 10 %) to add the loss components due to dc transport current up to 10 kA and both applied transverse and longitudinal ac fields. The measured total loss is always above the sum of the loss components.