AC losses in the Feather baseline cable Bas van Nugteren, Peng Gao, Jeroen van Nugteren, Sander Wessel, Marc Dhallé Video Conference 12 May 2015

Can we measure the inter-tape contact resistance R c ? (i.e. can we resolve the coupling loss Q C out of the hysteresis loss background Q H ) Important parameter for AC loss prediction, stability & quench propagation, field quality, … Can we validate the EM cable model? valuable design tool Goals Dynamic E.M. cable model J. van Nugteren

Strategy Detailed loss measurements of Q as function of amplitude, frequency and field angle  First-principle rationale:  hysteresis loss expected to scale with angle as Q H  cos 3  coupling loss as Q C  cos 2   expected ratio limiting values i.e. the hysteresis loss should decrease faster (and lower?) than the coupling loss when the field angle approaches the in-plane orientation  Rotate sample in dipole field  Measure magnetic moment vector (m // and m  )

Rough analytical estimates Loss map: total loss as function of frequency & amplitude (A.M. Campbell, Cryogenics 1982) H //, R c =  m 2 H //, R c =  m 2 Yellow = instrumental limit Black = resolution limit Blue = hysteresis-domintated; Red = coupling- dom. ; Green = saturation  Measure in high-frequency, low-amplitude limit  Challenging but not a-priori impossible (at least lower limit info)

Hardware  Combined classical magnetometer + calorimetric  Crossed set of pick-up (and compensation) coils

Hardware Dedicated sample holder First cool-down yesterday Experim. campaign next 2 weeks Sample (under cover, not visible) Dummy m // pick-up & compensation coils m  pick-up & compensation coils (under cover, not visible) Calorimeter l He inlet