Power Tracking Test Results

1. Power Tracking Test Results N. Sammut With several inputs from M. Lamont, M. Strzelczyk And inputs from W. Venturini, L. Bottura, S.Sanfilippo, L. Walckiers, S.Bouchenoua, G.Deferne, J. Miles, R. Mompo AB-OP

2. Test Program Postponed due to cryo limitation Not performed due to problems in 3) Power Tracking Test Results

3. 1st Result Ap2 Power Tracking Test Results

4. 2nd Result – after parameter readout error detected Ap1 Power Tracking Test Results

5. Hmm – indication that problem lies with static model b3 compensation of a cycle without decay and snapback Power Tracking Test Results

6. Hmm – pre-cycle ramp rate effects the loadline? Power Tracking Test Results

7. Ramp rate effect compensation Power Tracking Test Results

8. 3rd Result – after loadline compensation for ramp rate dependence Ap2 Power Tracking Test Results

9. Hmm – the residual magnetisation model needs to be improved? Power Tracking Test Results

10. 4th Result – after loadline compensation for ramp rate dependence and change of residual magnetisation model Ap2 Power Tracking Test Results

11. Hmm – are we suffering from lack of granularity in standard loadline measurement? Power Tracking Test Results

12. Hmm – are we suffering from lack of granularity in standard loadline measurement? Measurements without pre-cycle ramp rate compensation Power Tracking Test Results

13. Long injection residual magnetization artifact Power Tracking Test Results

14. 5th Result – after loadline compensation for ramp rate dependence and change of residual magnetisation model and increased points for loadline Power Tracking Test Results

15. Hmm – Lets compare model error to b3 compensation b3 compensation Model error Snapback error? Hysteresis error? Power Tracking Test Results

16. What if we model the static on the LHC cycle that we get when correctors are switched off? This indicates that it is probably snapback and/or corrector hysteresis Power Tracking Test Results

17. Open issue 1 – Is loadline reproducible? For long cycle maybe there is an effect of powering history (though decay compensation is proportional to difference in two loadline points) Power Tracking Test Results

18. Open Issue 2 - Does the Fixed Gain effect ? Sector 00-01 Gain = 0.1 (20comp) Gain = 2 (200comp) Should points be inverted? Dipole on at injection current, corrector on at ~ 50A Warning: might not be a reliable measurement Power Tracking Test Results

19. Open Issue 3 – Variation of measured sextupole with Shaft position Feed down error maybe? Power Tracking Test Results

20. Open Issue 4 – What is the effect of the corrector hysteresis? Power Tracking Test Results

21. Other considerations • Is timing wrong? 1s = 0.015units of b3 change in dipole • Snapback correlation might be different for this magnet • Snapback correlation might be affected by the loadline not being reproducible. (Also loadline was not compensated for ramp rate) Power Tracking Test Results

22. Proposal • Fix Shafts that have problems with sectors • Perform detailed loadline on each magnet (including SSS) (debug cycle) • Investigate well the difference in loadline measurements • Investigate effect of fixed gains and preferably have system with variable gains • Investigate variation of sextupole with shaft position • Perform detailed hysteresis measurements of all corrector types and investigate importance of this effect • Investigate timing • Find better fit for Residual Magnetisation • Maybe also investigate decay as a function of injection current • System such that current is saved in measurement entries (ease analysis considerably) • Use FAME for next measurement after a detailed characterisation and cross calibration of the instrument • Perform snapback measurement using Hall probe too Power Tracking Test Results