1. Ramping faster? Mike Lamont Ralph Steinhagen

2. I’(t) = 0 to avoid a voltage discontinuity “it has been shown that if I’(t) is kept low at the end of the snapback, the bandwidth of the control system required to dynamically correct this error can be substantially reduced.” Parabolic 6-3-12 Faster ramp?

3. the magnetic field error produced by inter-strand coupling current (and by other types of eddy currents) is proportional to the ramp rate B’ (t). Therefore, at a constant ramp rate the relative field error i cpl b is highest at low fields. The magnitude of this error can be optimized to be constant if the magnetic field ramp function B(t) is an exponential while ramping in such a way that with Exponential (from PN172) 6-3-12 Faster ramp? In fact:.. negligible for all harmonics

4. Linear – dictated by MB maximum ramp rate of 10 A/s Plus parabolic round off Linear & parabolic round-off 6-3-12 Faster ramp?

5. Ramp parameterization Faster ramp? 6-3-12

6. Snuggly fit the bits together Faster ramp? 6-3-12

7. Faster? Faster ramp? 6-3-12 ΔI sb didt end snapback B@end exp alphaLength Ramp [s] design200.635.9e-61095 2011/2012a120.91.62.2e-5760 2012b61.20.97.9e-5653 2012c41.40.81.6e-4632 alphaI@20s [A]didt@20s [A/s] Design5.9e-67620.18 2011/2011a2.2e-57670.675 2012b7.9e-57842.4 2012c1.6e-48094.9

8. 2011 Faster ramp? 6-3-12 6.7 A

9. 2012b Faster ramp? 6-3-12 23.9 A

10. Snapback Faster ramp? 6-3-12 Bottura & Sammut – Cham XIV

11. 6-3-12 Faster ramp? Snapback – Q’ Fit snapback: I(t) – MB current at time t I injection – injection value of current  b 3 and  I are fitting constants  b 3 and  I are correlated Sextupole compensation during snap-back in collaboration with FNAL – Luca Bottura

12. 1545 – no corrections(t) Faster ramp? 6-3-12 Tune modulation up ramp

13. 1580: QPH correction 6-3-12 Faster ramp? Faster ramp, faster snapback - less well compensated by model

14. Naked versus correction 6-3-12 Faster ramp?

15. Could save a couple of minutes by aggressive parabolic start Might worry about:  b3(t) – effective correction Could measure and adjust model  Ability to accurately measure Q’  Bandwidth of tune feedback  Other systems – RF… Conclusions 6-3-12 Faster ramp?