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This study investigates the limits, multipoles, and symmetries of a simulation framework for magnetic units. It also examines the dipolar response to pulsed field windings and the hysteresis and dynamic effects of magnetic fields.
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PS main magnetic units F. Sperati, D. Schoerling, A. Beaumont, M. Serluca, G. Sterbini
Outlook • 2015 • Simulation framework – Limits (1) • New tune investigation • 2016 • Simulation framework – Limits (2) • Simulation framework – Multipoles and symmetries • Dipolar response to PFW • Hysteresis and dynamic effect of B • 23/03/2017
Outlook • 2015 • Simulation framework – Limits (1) • New tune investigation • 2016 • Simulation framework – Limits (2) • Simulation framework – Multipoles and symmetries • Dipolar response to PFW • Hysteresis and dynamic effect of B • 23/03/2017
Simulation framework – Limits2015 • FEM model to represent real magnets • Validity check: comparing with measurements (bare machine) • Simulation: magneto-static • Conclusions: • Good prediction on dipoles and quadrupoles (= 1%) • Good guideline for B3 • 23/03/2017 Straight model!
Outlook • 2015 • Simulation framework – Limits (1) • New tune investigation • 2016 • Simulation framework – Limits (2) • Simulation framework – Multipoles and symmetries • Dipolar response to PFW • Hysteresis and dynamic effect of B • 23/03/2017
New tune investigation2015 • Bare machine, injection point • Tune increase to avoid resonances • Current tune: • New tune: • 23/03/2017 Image courtesy of R. Wasef
New tune investigation2015 • MADX: • Simulations: Find Impose conditions on multipoles (MADX values) Solve system (Obtain currents) Cross check in CCC Current situation: previous presentation (“7/7 optics”, M. Serluca) 23/03/2017
Outlook • 2015 • Simulation framework – Limits (1) • New tune investigation • 2016 • Simulation framework – Limits (2) • Simulation framework – Multipoles and symmetries • Dipolar response to PFW • Hysteresis and dynamic effect of B • 23/03/2017
Simulation framework – Limits2016 • POPS Magnetic model (Opera 3D) MADX • POPS PS CCC • : 1% relative error (B2) • : no match (B3) • Multipoles calculated with reference radius, but not in MADX! • 23/03/2017 multipolar representation: under discussion! 9
Outlook • 2015 • Simulation framework – Limits (1) • New tune investigation • 2016 • Simulation framework – Limits (2) • Simulation framework – Multipoles and symmetries • Dipolar response to PFW • Hysteresis and dynamic effect of B • 23/03/2017
Multipoles symmetries2016 • 23/03/2017 • Study of multipoles symmetries for each circuit • Implementation in MADX of the four different blocks resonance studies
Multipoles symmetries – POPS (injection)2016 • 23/03/2017
Multipoles symmetries – POPS (injection)2016 • 23/03/2017
Outlook • 2015 • Simulation framework – Limits (1) • New tune investigation • 2016 • Simulation framework – Limits (2) • Simulation framework – Multipoles and symmetries • Dipolar response to PFW • Hysteresis and dynamic effect of B • 23/03/2017
Dipolar response to PFW2016 • Cycle 0: 1500 Gs field, POPS controlled (602 A) • Auxiliary windings powered one by one, 50/100/150 A • 23/03/2017 • Observe field variation (BTRAIN) • Compare with 3D model
Dipolar response to PFW2016 • PFW influence: Δaux= • Relative errors ~10% • 23/03/2017
Outlook • 2015 • Simulation framework – Limits (1) • New tune investigation • 2016 • Simulation framework – Limits (2) • Simulation framework – Multipoles and symmetries • Dipolar response to PFW • Hysteresis and dynamic effect of B • 23/03/2017
Hysteresis and dynamic effect of B2016 • LHCINDIV cycle (1.4 GeV to 26 GeV) • No auxiliary circuits • No beam • Observable: BTRAIN dipolar component of B • Preceded by five different types of cycle: • ZERO (low energy) • SFTPRO2 (14 GeV) • TOF (20 GeV) • EAST2 (24 GeV) • LHC4 (26 GeV) • 23/03/2017
Hysteresis and dynamic effect of B2016 • 23/03/2017 dB/dt=0
Hysteresis and dynamic effect of B2016 • 23/03/2017 20 Gs/ms 8Gs/ms
Temporary conclusions • Simulation framework – Limits: • Sextupole unreliable chromaticity not yet predictable • Simulation framework – Multipoles symmetries: Implementation in MADX • Response to PFW: • Errors too big • Hysteresis and dynamic effect of B: Verified influence of dynamic effects • 23/03/2017
PS resistor cards • Eddy currents created during ramping of the PS magnetic field decreased and distorted • Idea: use PFW to compensate • Current situation: • Resistor cards installed on magnets • No knowledge of these cards • Two new vacuum chambers • Need of new resistor schemes • 23/03/2017 Field ramping Induced voltage in PFW loops Close loops with resistors Loop currents Compensation
Simulation framework – Limits2015 = 1% = 1% = 20%
Simulation frameworkMultipoles in 3D • 23/03/2017
Simulation framework – LimitsMultipoles at different reference radii • 23/03/2017