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PTC-ORBIT issues for PSB simulations V. Forte – E. Benedetto – M. Martini

PTC-ORBIT issues for PSB simulations V. Forte – E. Benedetto – M. Martini S.c. meeting (18/07/2013). OUTLINE We observed different “strange” behaviours in PTC-ORBIT simulations that should be fixed or, at least, explained by the code developers: Acceleration issues RF issues

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PTC-ORBIT issues for PSB simulations V. Forte – E. Benedetto – M. Martini

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  1. PTC-ORBIT issues for PSB simulations V. Forte – E. Benedetto – M. Martini S.c. meeting (18/07/2013)

  2. OUTLINE • We observed different “strange” behaviours in PTC-ORBIT simulations that should be fixed or, at least, explained by the code developers: • Acceleration issues • RF issues • Aperture related spikes • No-coincidence (and coincidence) of solutions PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  3. Acceleration issues: • Orbit seems to not recognize the acceleration imposed through PTC RF tables showaccelerate(fio) PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  4. The energy path described in the table is the following… PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  5. Acceleration issues: ORBIT diagnostics Statistical Twiss + dynamic energy (from RF table) Horizontal RMS emittance Fixed Twiss (from Twiss PTC table) + dynamic energy (from RF table) Fixed Twiss (from Twiss PTC table) + static energy (160 MeV) Vertical RMS emittance Orbit seems to not recognize the acceleration imposed through PTC RF tables The Orbit diagnostics confirm the hypothesis. In fact these are similar to post-processing calculations using fixed Twiss and a constant 160 MeV kinetic energy PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  6. Acceleration issues: • Orbit seems to not recognize the acceleration imposed through PTC RF tables • This can cause problems in: • Diagnostics (Dp/p calculation…) • Space charge computation MUST BE FIXED! PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  7. RF table definition: • In case of acceleration (Bdot ≠ 0), the longitudinal phase space is (artificially?!) shifted by PTC in order to use f=0 as a fixed point. While, without acceleration, this is a direct consequence of the equations (0 stable phase), it shouldn’t be in case with acceleration. PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  8. 8 kV (h=1) + 8 kV (h=2) in phase without acceleration The +time command must be used for space charge simulations and causes a shift of p in phase. PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  9. 8 kV (h=1) + 8 kV (h=2) in phase without acceleration (swapped sign in PTC-ORBIT) For this reason the sign of the voltages must be swapped. 8 (h=1) & 8 (h=2) in phase -> -8, -8 PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  10. 8 kV (h=1) + 8 kV (h=2) in phase with acceleration For this reason the sign of the voltages must be swapped 8 (h=1) & 8 (h=2) in antiphase -> -8, +8 8 (h=1) & 8 (h=2) in phase -> -8, -8 PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  11. 8 kV (h=1) + 6 kV (h=2) in phase with acceleration PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  12. 8 kV (h=1) + 8 kV (h=2) in antiphase without acceleration SFP @ 1.047 rad ~ 60 deg Synch. period ~ 712 turns Synch.period ~ 482 turns PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  13. 8 kV (h=1) + 8 kV (h=2) in antiphase with acceleration SFP @ 1.365 rad ~ 78 deg Synch. period ~ 780 turns Synch. period ~ 482 turns The sign of the voltages must be swapped 8 (h=1) & 8 (h=2) in antiphase -> -8, +8 PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  14. 8 kV (h=1) + 6 kV (h=2) in antiphase without acceleration SFP @ 0.8568 rad ~ 49 deg Synch. period ~ 745 turns Synch. period ~ 655 turns PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  15. 8 kV (h=1) + 6 kV (h=2) in antiphase with acceleration PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  16. RF table definition: • In case of acceleration (Bdot ≠ 0), the longitudinal phase space is (artificially?!) shifted by PTC in order to use f=0 as a fixed point. While, without acceleration, this is a direct consequence of the equations (0 stable phase), it shouldn’t be in case with acceleration -> (0,0) is not a solution of the equations anymore. • This can cause problems in: • Defining complex energy paths (i.e. acceleration->static energy) without transition (i.e. from acceleration to static energy) mismatch • Longitudinal matching is possible only after single particle tracking to be sure of the bucket position(trick) The way this shift is performed must be analytically clear! PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  17. Aperture-dependent spikes PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  18. No-coincidence of solutions PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  19. No-coincidence of solutions PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  20. coincidence of solutions • (without apertures) PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

  21. CONCLUSIONS • We observed different “strange” behaviours in PTC-ORBIT that should be fixed or, at least, explained by the code developers. • Solutions (or explanations) should be provided soon to avoid slacks in simulations. PTC-ORBIT issues for PSB simulations - V. Forte – E. Benedetto – M. Martini - S.c. meeting (18/07/2013)

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