PETRA III Beam Dynamics Issues Dynamic Aperture Vertical Emittance Control Experiments at PETRA II 5th DESY MAC, 1.6.2005 Winni Decking, DESY-MPY 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Dynamic Aperture 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Dynamic Aperture • Loss-free injection requires horizontal aperture of 30 mm mrad • Touschek lifetime requires off-momentum aperture of 1.5 % 35 without all insertion devices with all insertion devices 30 25 20 (mm mrad) 15 y A 10 5 0 0 20 40 60 80 100 120 A (mm mrad) x 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Dynamic Aperture Large cross-term due to sextupoles limit horizontal DA Wigglers and Undulators enhance vertical detuning with vertical amplitude Present sextupole scheme: 2 families within 72deg lattice correct chromaticity first order perturbations cancelled after 5 cells d(Qx)/d(Ex) d(Qy)/(dEy) d(Qy)/d(Ex) -4.75E+02 -1.85E+02 -3.30E+03 More sextupole families to tackle cross term? 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY PETRA III ‘Symmetries’ Octant (-B) -B C 13 FBDB 2 FODB B D 10 regular FODO cells -B A A -A 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Sextupole Schemes symmetry point 5*(S1,S2) 5*(S1,S2) 5*(S1,S2) 5*(S3,S4) SH1,SH2 5*(S1, S2) 5*( S1,S2) SH3,SH4 5*(S1,S2,S3,S4) β [45m] D [1m] 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Results • Two family scheme further optimized (working point, …) • Non-interleaved four family scheme allows to reduce cross-term. on the expense off other detuning terms • Harmonic sextupoles get very strong (4 harmonic sextupoles/20 chromatic sextupoles), DA < 5 mm mrad • 4 interleaved families show slight improvement of DA Further Work: • fitting DA directly instead of single detuning/resonance terms (very CPU consuming) 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Influence of Errors on DA - I • Optic errors – Beta-beat of ≈ 10 % shows no effect on DA – Increased beta-beat reduces DA slightly => commissioning issue • Orbit errors – DA rather sensitive to orbit errors (RMS of < 1 mm reduces DA by 20 %) – Not fully understood – No issue for routine operation because of tight orbit control – Commissioning issue 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY PETRA III – New Octant Magnets long Quadrupole Dipole short Quadrupole wide Aperture Corrector 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Influence of Errors on DA – II • Multipole errors of new octant magnets – Originally specified relative octupole (5e-4 at nominal field) found to reduce DA by 30% – Requirement reduction to 1e-4 yields no DA toll – S. Petrov’s talk • Sextupole fields induced by back leg correction coils • Sextupole fields in wide aperture vertical correctors – Values of up to 1% of nominal sextupole field acceptable because of random distribution of error 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Further Activities • Wiggler treatment – Wiggler treatment discussed within ILC mini workshop on Damping wigglers – PETRA damping wiggler chosen as bench-mark example to compare field-fitting and tracking models • New wiggler in DORIS storage ring reduces lifetime/DA, study in progress using tools developed for PETRA damping wigglers • Compare measured DA of PETRA II with tracking calculations 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Vertical Emittance Control 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Emittance Control Emittance ratio (goal): 1% (10 pm vertical emittance) 25 Tolerances on dispersion: 20 ts Dx [mm] Dy [mm] n 15 Wiggler section 18 5 10 * No. of Eve Undulator section 20 3 5 0 FODO Arcs 58 2345678 RMRMSS VerticalVertical Dispersion(mm Dispersion ) DBA Arcs 22 31 after correction (600 seeds) * includes beam size contribution due to energy spread 70 Combined orbit & dispersion correction 60 using all BPM’s (206) and correctors (182/189) 50 40 30 20 No. of events 10 0 0.03 0.04 0.05 0.06 0.07 0.08 0.0 RMVeSrti Verticalcal rms orb Orbitit(m m) after correction (600 seeds) 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY ‘Localized’ Correction Methods I - Steerer Initial orbit correction Dispersion correction with limited number of BPM’s and correctors εy(RMS) ≈ 15 pm rad Vertical difference orbit after dispersion correction Vert. Corrector (21) BPM (26) Vertical dispersion after dispersion correction 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY ‘Localized’ Correction Methods II – Skew Quads Initial orbit correction Dispersion correction with limited number of BPM’s and skew quads εy(RMS) ≈ 15 pm rad Vertical difference orbit after dispersion correction Skew Quad (12) BPM (26) Vertical dispersion after dispersion correction 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Results • Localized methods miss emittance goal by factor of 1.5-2 • Further Studies: – Refine schemes (more monitors/correctors) – Improve truly localized orthogonal bumps (skew quadrupole dispersion bumps disturb linear optics) – Correct on coupling resonance(s) instead of dispersion 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Measurements at PETRA II 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Measurements at PETRA II •Tools: – Implementation of interface to allow usage of MATLAB toolbox developed for HERA (took longer than anticipated) – Single turn kicker – Single turn BPMs – Diagnostic scrapers •Goals – Characterization of diagnostics – Characterization of optics – Advanced orbit/dispersion correction – Dynamic aperture studies – Injection efficiency studies 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Orbit Response Matrix (ORM) Measurements • Measurement of BPM/steerer response • 118/111 × 113 matrix per plane allows fitting of – BPM gains (113 – Steerer gains (118/111) – Quadrupole gradients (28 families, xx individual quadrupoles) –….. • Methods used – direct error fit (LOCO (J.Safranek), CALIF (V. Ziemann)) method – beta-/phase fit (G. Hoffstaetter, J. Keil) 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY ORM - Results •BPMs – gain factors corrected –Gainrms≈3%, still to large for the measured 10-20 µm BPM resolution • Correctors 1.4 1.4 i 1.2 i 1.2 or c or c t t c c a 1 a 1 ale F ale F Sc 0.8 Sc 0.8 0.6 0.6 0 20 40 60 80 100 120 0 20 40 60 80 100 120 Horizontal Corrector # Vertical Corrector # Horizontal: Vertical: large spread due to back leg systematic scaling factor variation windings and neglecting due to influence of adjacent hysteresis effects magnets 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Vertical Correctors 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Gradient Errors Quadrupole Gradient Errors (ORM 11.05.05) RMS(∆K/K) ≈ 1 % in 2004 Q6B Q6A Q5B Q5A Improved cycling procedure Q4B Q3B Q1B Q0K2 RMS: 0.2 % Q1K RMS(∆K/K) ≈ 0.2 % in 2005 Q2K Q4K Q5K Q0A Q2A Q4A QD QF Q4B Q2B Q0B Q9N Q7N Q6N Q5N Q4N Q3N Q2N Q1N Q0N2 -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 ∆ K/K 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Calculated Beta-Beat Beta-beating due to quadrupole errors (ORM 11.05.05) 1 ] [% x β 0 / x β ∆ -1 0 500 1000 1500 2000 2500 2 ] [% y β 0 / y β ∆ -2 0 500 1000 1500 2000 2500 s [m] to good to be true ? 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Orbit/Dispersion Correction • Orbit at PETRA II corrected to below 1 mm RMS • Vertical dispersion below 2 cm RMS (goal 5 mm RMS) • Work in progress 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Dynamic Aperture Studies • Study of dynamic aperture for 2 different PETRA lattices: – Booster injection lattice (PEM04) • Tunes 25.2/23.3 • Calculated DA ≈ 25 mm mrad – Synchrotron radiation lattice (PESYN) • Tunes 33.26/26.31 (similar to PETRAIII) • Calculated DA ≈ 12 mm mrad • Numerical investigations performed, experiments to be started 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY The Team • Yongjun Li – Dynamic Aperture Calculations • Gajendra Kumar Sahoo – Orbit Correction • Joachim Keil – Orbit Response Matrix •WinfriedDecking • Klaus Balewski 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Summary • Beam dynamics activities focus on improvements of the baseline layout – Dynamic aperture – Emittance control • Rich measurement program at PETRA II developed – Most of the diagnostics and tools ready – Supportive numerical investigations performed – First results obtained 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Appendix 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY PETRA III Parameters Without ID Wiggler Wiggler & Undulator Tune 37.25 / 33.20 Nat. Chromaticities -47 / -50 I2 6.3e-2 2.6e-1 3.3e-1 Energy Loss/turn 1.15 MeV 4.66 MeV 6.03 MeV Hor. Emittance 4.65 nm rad 1.2 nm rad 0.9 nm rad Energy Spread 0.083 % 0.0126% 0.0123% Bunch length 8.3 mm 12.7 mm 13.5 mm Damping times 80/40 ms 20/10 ms 15/7.5 ms 10400 turns 2600 turns 1950 turns Rev. Frequency 130.118 kHz Acceptance 30 µm / 2.2 µm / 1.5 % http://adweb.desy.de/p3/01-Accelerator/GP-02_General_Parameters/p3-parameter.xls 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY Search for Optimal Working Point Tune scan 04−Dec−2004 06:56:27 0 0.3 0.28 −1 0.26 0.24 −2 0.22 y ν −3 0.2 0.18 −4 0.16 0.14 −5 0.12 −6 0.2 0.25ν 0.3 0.35 x tune scan with initial conditions: tune scan with initial conditions: Ax=1 mm mrad Ax=20 mm mrad Ay=0.1 mm mrad Ay=0.5 mm mrad δ=0.1% δ=0.0% 5th DESY MAC PETRA III Beam Dynamics Issues Winni Decking - DESY.