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Code versus Experiment Benchmarking of the PSB Half Integer Resonance with SC

Code versus Experiment Benchmarking of the PSB Half Integer Resonance with SC Space charge meeting – CERN - 08/05/2014. Layout The half-integer resonance measurements Simulations with PTC-Orbit. Vincenzo Forte Thanks to: E. Benedetto, M. McAteer, F. Schmidt.

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Code versus Experiment Benchmarking of the PSB Half Integer Resonance with SC

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  1. Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewithSC Space charge meeting – CERN - 08/05/2014 Layout The half-integer resonance measurements Simulations with PTC-Orbit Vincenzo Forte Thanks to: E. Benedetto, M. McAteer, F. Schmidt

  2. Measurements and achievements Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  3. Measurements: half integer resonance crossing… (static w. point above 2Qy=9) QNO816L3 ON QNO816L3 OFF 2Qy=9 crossing @ C450 (switching off QNO correctors) QNO816L3 ON QNO816L3 OFF Qy = 4.53 Qx = 4.28 Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  4. Measurements: half integer resonance crossing… (static w. point above 2Qy=9) Almost constant transverse sigmas! Horizontal Vertical Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  5. Horizontal PSB space charge studies update Vincenzo Forte – BE-ABP/LIS meeting – CERN - 04/11/2013 PSB Experiments, 6D Tune evolution with SC Vincenzo Forte – Space charge meeting – CERN - 20/05/2014

  6. Vertical PSB space charge studies update Vincenzo Forte – BE-ABP/LIS meeting – CERN - 04/11/2013 PSB Experiments, 6D Tune evolution with SC Vincenzo Forte – Space charge meeting – CERN - 20/05/2014

  7. Measurements: half integer resonance crossing… (static w. point above 2Qy=9) 8kV/4kV in antiphase (long) 8kV/8kV in phase (short) DOUBLE HARMONIC RF SYSTEM 8kV/8kV in antiphase (long) Cases in analysis Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  8. Measurements: quadrupolar field and misalignment errors • To drive the 2Qy=9 resonance a set of quadrupolar errors is necessary. Without these, it would be impossible to appreciate the effect of the resonance on the beam. • The misalignment errors are also provided. • A realistic errors model is used for the simulations. Courtesy M. McAteer Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  9. Simulations: losses behavior for long bunch No errors – With s.c.(4.285, 4.517) Quad field errors - No s.c.(4.285, 4.517) Quad field errors - With s.c.(4.285, 4.517) Quad field errors – Misalign. errors – With s.c.(4.284 4.513) Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  10. Simulations: losses behavior for long bunch and short bunch Short bunches lose more slowly and with different losses profiles. Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  11. Simulations (with quad fields and misalign. errors): 200 mstransverse evolution Tails from ~c600 The beam size (1sgaussian interpolation) is preserved along the cycle, as in the measurements Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  12. Simulations (with quad fields and misalign. errors): 200 mslosses vs y position profiles Long bunch Initially the losses are mainly for bigger transverse vertical particles… …then the spread reduces and also particles in the core start getting lost. Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  13. Simulations (with quad fields and misalign. errors): 200 mswaterfall evolution Long bunch Short bunch Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  14. Simulations (with quad fields and misalign. Errors): 5-200 ms long. profiles remained particle Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  15. Simulations (with quad fields and misalign. Errors): 5-200 ms long. profiles lost particles After c550 the losses start to concern the basins of attraction (islands) around ~+/− 1 rad Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  16. Simulations: losses behavior for long bunch Change of losses regime The losses rate seems to be connected to the synch period. After c550 the losses regime becomes faster and the losses regard mainly the islands around the outer fixed point (@~+/− 1 rad). These particle, which rotate at smaller synch. period, are lost more quickly! Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  17. Simulations: losses distribution (long bunch) • In case of only quad field errors (blue) the losses distribution is mainly concentrated in the beamscope window, as expected is the closed orbit is zero. • In case of quad field errors + misalignment errors (red) the losses distribution in the machine changes. Beamscope window Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  18. Tunes Simulations (with quad field errors): after ~35ms and ~115ms C485 on the magenta curve C565 on the magenta curve (Single turn) tunes computation Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  19. Tunes Simulations (with quad fields): after ~35ms and ~115ms C485 on the magenta curve C565 on the magenta curve Avg. tunes (over 1500 turns) Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  20. Tunes Simulations (with quad fields C485 on the magenta curve C565 on the magenta curve Selecting particles inside Qy=4.5 +/− 0.001… Particles with smaller spread sit on vertical transverse islands! Red because it gets lost Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  21. Simulations (with quad field and s.c.) Vertical plane (Qycolorbar) After 5000 turns After 115000 turns Big diffusion (and tailing) after 115 ms Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  22. Conclusions • Benchmark results between measurements and PTC-Orbit have been shown for a case around the half-integer 2Qy=9 resonance in the PSB ring 2. • The (very long) simulations show very good agreement with the phenomena observed in control room. • Non-linear dynamics phenomena are directly connected to the machine errors and can be analysed through the software (transverse islands, different losses regimes for non-linear buckets…). • These results can be useful for other machines at CERN (Leir?), for which a capture with a shorter bunch could improve the performance (in the PSB one save up to 50 % of the beam over long term – see first slides). Can the tune spread be a friend sometimes? It seems so… Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  23. APPENDIX Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  24. Tunes Simulations (with quad fields): after ~5ms for long and short bunch Long bunch Short bunch Single turn tunes computation Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  25. Tunes Simulations (with quad fields): after ~5ms and ~75ms Single turn tunes computation Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  26. PTC-ORBIT VERSIONS ISSUE No errors – with s.c. quad field + misalign. Errors (last PTC-Orbit) – 2nd shot With quad field errors but without s.c. quad field + misalign. Errors (last PTC-Orbit) Almost identical results (green-yellow) two shots with the latest version (but they should be identical after fix!) Only quad field errors – with s.c. quad field + misalign. Errors (old PTC-Orbit) Differences between the old PTC-Orbit and the latest one Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  27. Simulations (with quad fields and misalign. errors): 200 mslosses vs y position profiles Short bunch Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

  28. Simulations (with quad fields and misalign. errors): 200 mslosses longitudinal Long bunch Code versus ExperimentBenchmarking of the PSB HalfIntegerResonancewith SC Vincenzo Forte – Space charge meeting – CERN - 08/05/2014

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