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Prediction of hysteresis with different squeeze scenarios

Prediction of hysteresis with different squeeze scenarios. P. Hagen November 2010. Hysteresis during squeeze. There are 3 components in the FiDeL model which contribute to hysteresis: PEN - current penetration in the cable filaments ( low currents )

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Prediction of hysteresis with different squeeze scenarios

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  1. Prediction of hysteresis with different squeeze scenarios P. Hagen November 2010

  2. Hysteresis during squeeze • There are 3 components in the FiDeL model which contribute to hysteresis: • PEN - current penetration in the cable filaments (low currents) • DCMAG - persistent currents in SC magnets • RESMAG – residual magnetisation of materials • DCMAG depends upon the sign of the dI/dt (ramp up or down)We do not know the exact conditions (Δt, ΔI) causing a switch of branch • During the squeeze many magnets around the collision IPs change ramp direction • We assume DCMAG is the dominant source of hysteresis, and for RESMAG, FiDeL gives us in any case only 1 branch; ramp-up (see next slide) • We assume the de-composition of the transfer function is correct (the split between DCMAG and RESMAG is physical and not just a fit!)

  3. Example of TF with hysteresis h not given by FiDeL • Example MQWA, warm magnet with full operational cycle • In FiDeL we model TF only for the ramp-up • The different path for ramp-down is not present in FiDeL • The size of the hysteresis depends upon Imin and Imax

  4. Data sources for following tables • Optics from /afs/cern.ch/eng/lhc/optics/V6.503/IPn • FiDeL TF by circuit • WISE with 3.5 TeV ramp

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