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NSLS II Injection

NSLS II Injection. R. Heese, I. Pinayev, D. Raparia, J. Rose, T. Shaftan. Injector Options. Full energy linac – normal or SC Compact booster Booster in same tunnel as main ring With these factors in mind Top-off mode for main ring Reliability Presence of 600 MeV IR ring

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NSLS II Injection

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  1. NSLS II Injection R. Heese, I. Pinayev, D. Raparia, J. Rose, T. Shaftan

  2. Injector Options • Full energy linac – normal or SC • Compact booster • Booster in same tunnel as main ring With these factors in mind • Top-off mode for main ring • Reliability • Presence of 600 MeV IR ring • Cost of construction and operation

  3. Injector Considerations at this time • Injector is not a state-of-the-art system • The ring is still a moving target – length of injection straights not settled, increase to 3.6 GeV ring energy possibility was recently asked for • Ring fill requirements sets charge transfer capability – initial fill time, max. allowable current fluctuations in top-off mode • Emittance requirements • Compact booster vs. booster in same tunnel • Injector linac energy requirement – remember IR ring requires 600 MeV

  4. NSLS-II injection Outline • NSLS-2 Injection specifications • Single-bunch and Multi-bunch modes • Top-off • Choice of injector: Linac  Booster • Injection bump geometry, specs and performance • E-gun and low energy linac baseline design

  5. t NSLS-II Injection Specs • Lifetime ~ 2 - 3 hours (no Harmonic Cavity) • Filling pattern uniformity = 20 % bunch-bunch can be tolerated (remember gap in bunch pattern) • Average current stability = ~ 0.5% • Time between top-off cycles = 60 s • 3.6 GeV, 500 mA, ~ 1560 buckets, 5/6 of them filled  1.0 nC/bucket + IR ring at 600 MeV Ī t Ib bunch # Ī t QI \\Nslsnt1\AccPhy\NSLS2_Injection\

  6. X-ray ring IR ringX-ray ring Energy (GeV) 0.6 3.0 Circulating Current (A) 1.5 0.5 (.24 at 3.6) Circumference (m) 72 936 Revolution period (μs) 0.24 3.12 RF frequency (MHz) 500 500 Circulating charge (μC) 0.36 1.56 Number of buckets (Buckets filled) 120 (~80) 1560 (~1300) Charge per bucket (nC) 4.5 1.2 Current per bucket (mA) 18.7 0.38 Lifetime (min) 90 180 max. Interval of t/o cycle (min) 10 1 Current variation over t/o cycle 10% 0.5% Current variation over t/o cycle (mA) 150 2.5 Charge variation over t/o cycle (nC) 36 8.5 Damping time (ms) 45 75 Charge Transfer Requirements

  7. Single-bunch injection mode Injector Rate (Hz) Time to fill ring Time to top-off Overall time spent on top-off injection, % 1 (Booster) 36 minutes! 33 20 s 10 (Linac) 210 s 2.0 5 50 (Linac) 43 s <1 0.4 • Booster in single-bunch mode is too slow for top-off injection and initial fill  multi-bunch injection mode of 20 – 50 bunches at a time is necessary • For single bunch transfer, linac at 50 Hz is required for first fill and top-off • No need to consider anything faster than 50 Hz due to ring damping time

  8. Multi-bunch injection Bunch train mode injector Storage Ring • Short lifetime  multi-bunch transfer mode is necessary • SLS experience: feedback for enhancement of the bunch pattern purity • “Hunt&Peck” mode: is it necessary for NSLS-II ? • Works for linac-injector • “Flat-top ramp” mode in the booster to store beam while timing system selects bunches • Short pulse kickers – may be difficult at this frequency • Solution is to modulate linac e-gun trigger with inverse of targeted ring pulse train, or – laser-driven photo cathode? Ib SR bunch pattern #bunch “Hunt&Peck” mode injector Storage Ring Ib SR bunch pattern #bunch

  9. “Stay Clear” of injected horizontal beam

  10. “Stay Clear” of injected vertical beam

  11. Choice of NSLS II Injection System • Full energy linac was rejected due to cost, especially since 3.6 GeV was expected and since no driving need to expand to FEL in the future was forthcoming • Compact booster with 600 MeV linac was our second choice solely due to cost of building • The system of choice is a booster in the same tunnel as the storage ring with a 600 MeV injector linac, also serving as injector into IR ring • Cost of in tunnel booster is less than compact booster by building cost - although ring is longer and needs a few more PUE’s, steering magnets and pumps, it’s mostly empty pipe, RF system is cheaper, power supplies for low-field magnets cost less

  12. 0.6 m 0.85 m 0.6 m 1.9 m 0.6 m 0.85 m 0.6 m Δ=15 mm 0.1 m 0.3 m 6.4 m Stylized NSLS-II Injection Geometry

  13. Injection Septum B 0.89 T Lengtheff 2000 mm Θ 148 mrad L 4.8 μH Ipeak 10 kA V 2100 V H x V 20x10 mm² Ferrite EBG V270-035A Pulse 60 μsec ½sine wave Injection Kicker B 0.148 T Lengtheff 650 mm Θ 10 mrad L 1.8 μH Ipeak 6550 A V 7.5 kV H x V 70x40 mm² Ferrite CMD 5005 Pulse 5 μsec ½sine wave Possible NSLS II Septum and Injection Kickers

  14. Injection System Hardware Thoughts • All kickers may be run in series and tuned to reduce the integrated field through the injection straight to zero – nullifies effects of timing errors and mismatch • Kickers can then be on longer than 5 μsec, reducing voltage requirements (Revolution period >3 μsec!) • Since booster is above ring in the tunnel, a Lambertson septum can be of advantage, giving DC field cancellation capability resulting in a totally closed injection orbit bump

  15. 0.5 mm 0.5 mm 6 3 mm 3 2 7.6 mm 6.6 mm X’ (mrad) 4 5 3·i COE=2mm 1 X (mm) Phase space for 6 turns

  16. Injector Linac Requirements • Minimum energy 600 MeV to serve as full energy injector for IR ring • Capable of 50 bunch train at 500 MHz of at least 500 pC each • (30 m or 100 nsec long) • Requires sub-harmonic (1/6) buncher at ring/booster frequency • At least 1Hz rep rate, 3 – 5 Hz better for IR ring fill • High reliability requires redundancy 9 accelerating sections giving >700 MeV capability • 10 45 MW Klystrons/Modulators (Hot stand-by for section #1) • Possibly 2 e-guns with switched low energy beam transport

  17. TURN-KEY Solid State MODULATOR SYSTEM KLYSTRON Solenoid PULSE TRANSFORMER SOLENOID DCPS SOLID STATE SWITCH MODULE SOLENOID PS & IPPS RF-SOURCE & AMPLIFIER • Benefits: • Greatly Improves Reliability, Maintainability • Smaller footprint • Variable pulse width can be used to increase rep rate within average • power limits: 5 μs at 50 Hz, .75 μs at 300 Hz. SLED vs. FEL performance Slide courtesy of Mikael Lindholm, ScandiNova

  18. S-Band Structures • Parameter: • mode 2p/3 • frequency 2.9983 GHz • length 5.2 m • no. of cells including absorber 150 + 6 • shunt imp. 51 MW/m • Q 14000 • filling time 0.74 ms • Slide courtesy of ACCEL 130k EU each

  19. ASP booster (Danfysik) 4.5m • Energy: 0.13 GeV • Rep. Rate: 1 Hz • Circumference: 130 m • RF frequency: 500 MHz • Emittance: 30 nm rad • Radiation loss: 743 keV/turn • Beam current: >5 mA • Magnet power: 240 kW • Booster cost = 100 MeV linac+3 GeV booster+2 transport lines+installation and commissioning=21 M$ 20m 4.5m y x 0.5m 32.7m  -0.5m

  20. Booster map SR injection Booster 600MeV linac Electron gun

  21. Compact injector with IR ring(Stylized)

  22. Compact Booster Lattice designNote: “Compact” booster is larger than NSLS X-ray ring Regular cell • 24 TME cells (NSLS-I booster) • Two 8 m long straight sections • 24 combined function magnets (L=2m, =13.85, n=17) • 4 Dispersion suppressors • 38 quadrupoles (5 families) • Sextupoles (2 families) are integrated into dipoles and quads  DA>30 mm • Chromaticity: -28.6; -8.6 • Tunes 12.16; 4.36 • Momentum compaction 0.035 Dispersion suppressor

  23. 32-cell FODO @ 3.5 GeV BMPM output ------------------------------------------------------------- Synchrotron integrals: I1 I2 I3 (C)I4 I5 I6X I6Y I8 5.1099E+01 8.2247E-01 5.3830E-02 1.8495E+00 5.0055E-02 7.1938E+00 4.8981E+00 4.3217E+00 Global machine parameters (two beams), and local parameters at interaction point: Q_x = 9.4781 beta_x* = 39.820 [m] etax* = 5.2596 [m] Q_y = 5.8679 beta_y* = 14.966 [m] etay* = 0.0000 [m] alpha = 5.5064E-02 circumf. = 928.00 [m] t_0 = 3.0955E-06 [sec/turn] (C)J_x = -1.2488 J_y = 1.0000 (C)J_e = 4.2488 dJ_x/(dE/E) = -10.509 dE/E = 0.21398 df_RF = -5.9380E+06 [Hz] Beam parameters and luminosities: (D)energy = 3.5000 [GeV] (C)coupling = 0.0000 (C)delta_Q = NaN U0 = 1.7377 [MeV/turn] sig_E = 5.2623E-04 dE/E B*rho = 11.675 [Tm] tau_x = -9.9855E-03 [sec] tau_y = 1.2470E-02 [sec] tau_E = 2.9349E-03 [sec] E_x_0 = -.87610 pi [micro-m] (C)E_x_c = 0.87610 pi [micro-m] sig_x_0 = 5.9064 [mm] sig_x_c = 5.9064 [mm] sig_x_T = 5.2178 [mm] sig_y_0 = 0.0000 [mm] sig_y_c = 0.0000 [mm] sig_y_T = 0.0000 [mm] L_x = Infinity [1/cm**2 sec] n_x = 6.2650E+11 per beam (C)I_x = 3.2427E-02 [A] / bunch L_y = NaN [1/cm**2 sec] n_y = 0.0000 per beam I_y = 0.0000 [A] / bunch k_bunch = 1 tau_pol = 53.972 [min] tau_brems = 0.0000 [min] n_int = 2 pol_infinit. = 92.376 percent RF related parameters (for a total of 1 cavities): f_RF/f_0 = 1560 (D)volt._RF = 2.0000 [MV] f_RF = 503.96 [MHz] phi = 119.68 [degrees] Q_s = 6.2191E-02 f_synchr. = 20.091 [kHz] (C)sig_buck. = 4.3695E-04 sig_s = 68.815 [mm] (C) tau_Q = 1.0015E-04 [min] shunt imp. = 0.0000 [MOhm/m] L_cavity = 1.0000E-03 [m] t_fill = 25.000 [microsec] (C)power = Infinity [MW] K_hm = 0.0000 [V/pC] (C)beta_RF = 1.0000 (C)psi = 0.0000 [degrees] (C)bucket = 0.83033 32-cell FODO @ 3.5 GeV "MAD" Version: 8.51/15 Run: 19/04/06 22.58.20 32-fold FODO

  24. 64-cell FODO @ 3.5 GeV BMPM output page 1 ------------------------------------------------------------------------------------ Synchrotron integrals: I1 I2 I3 (C)I4 I5 I6X I6Y I8 1.2174E+01 8.2247E-01 5.3830E-02 1.6936E+00 5.8403E-03 6.6427E+01 5.3111E+01 4.8825E+00 Global machine parameters (two beams), and local parameters at interaction point: Q_x = 19.976 beta_x* = 22.297 [m] etax* = 1.2832 [m] Q_y = 13.441 beta_y* = 5.9350 [m] etay* = 0.0000 [m] alpha = 1.3210E-02 circumf. = 921.60 [m] t_0 = 3.0741E-06 [sec/turn] (C)J_x = -1.0592 J_y = 1.0000 (C)J_e = 4.0592 dJ_x/(dE/E) = -11.873 dE/E = 0.17344 df_RF = -1.1626E+06 [Hz] Beam parameters and luminosities: (D)energy = 3.5000 [GeV] (C)coupling = 0.0000 (C)delta_Q = NaN U0 = 1.7377 [MeV/turn] sig_E = 5.3839E-04 dE/E B*rho = 11.675 [Tm] tau_x = -1.1692E-02 [sec] tau_y = 1.2384E-02 [sec] tau_E = 3.0508E-03 [sec] E_x_0 = -.12052 pi [micro-m] (C)E_x_c = 0.12052 pi [micro-m] E_y_c = 0.0000 pi [micro-m] sig_x_0 = 1.6393 [mm] sig_x_c = 1.6393 [mm] sig_x_T = 1.4866 [mm] sig_y_0 = 0.0000 [mm] sig_y_c = 0.0000 [mm] sig_y_T = 0.0000 [mm] L_x = Infinity [1/cm**2 sec] n_x = 9.0824E+10 per beam (C)I_x = 4.7336E-03 [A] / bunch L_y = NaN [1/cm**2 sec] n_y = 0.0000 per beam I_y = 0.0000 [A] / bunch k_bunch = 1 tau_pol = 53.600 [min] tau_brems = 0.0000 [min] n_int = 2 pol_infinit. = 92.376 percent RF related parameters (for a total of 1 cavities): f_RF/f_0 = 1560 (D)volt._RF = 2.0000 [MV] f_RF = 507.46 [MHz] phi = 119.68 [degrees] Q_s = 3.0461E-02 f_synchr. = 9.9088 [kHz] (C)sig_buck. = 8.9211E-04 sig_s = 34.246 [mm] (C) tau_Q = 7.3085E-05 [min] shunt imp. = 0.0000 [MOhm/m] L_cavity = 1.0000E-03 [m] t_fill = 25.000 [microsec] (C)power = Infinity [MW] K_hm = 0.0000 [V/pC] (C)beta_RF = 1.0000 (C)psi = 0.0000 [degrees] (C)bucket = 1.6570 164-cell FODO @ 3.5 GeV "MAD" Version: 8.51/15 Run: 19/04/06 23.11.46 64-fold FODO

  25. NSLS-Booster-like lattice with 64 cells BMPM output ------------------------------------------------------------------ Synchrotron integrals: I1 I2 I3 (C)I4 I5 I6X I6Y I8 1.6574E+00 4.1123E-01 2.6915E-02 -3.6669E-01 4.5753E-04 1.4459E+02 6.8270E+01 3.3585E+00 Global machine parameters (two beams), and local parameters at interaction point: Q_x = 15.879 beta_x* = 22.811 [m] etax* = 0.73259 [m] Q_y = 12.188 beta_y* = 6.2665 [m] etay* = 0.0000 [m] alpha = 1.8109E-03 circumf. = 915.20 [m] t_0 = 3.0528E-06 [sec/turn] (C)J_x = 1.8917 J_y = 1.0000 (C)J_e = 1.1083 dJ_x/(dE/E) = -16.334 dE/E = -5.4592E-02 df_RF = 40804. [Hz] Beam parameters and luminosities: (D)energy = 3.5000 [GeV] (C)coupling = 0.86212 (C)delta_Q = 6.0000E-02 U0 = 0.86884 [MeV/turn] sig_E = 1.0303E-03 dE/E B*rho = 11.675 [Tm] tau_x = 1.3002E-02 [sec] tau_y = 2.4595E-02 [sec] tau_E = 2.2192E-02 [sec] E_x_0 = 1.0573E-02 pi [micro-m] (C)E_x_c = 6.0651E-03 pi [micro-m] E_y_c = 8.5275E-03 pi [micro-m] sig_x_0 = 0.49110 [mm] sig_x_c = 0.37196 [mm] sig_x_T = 0.84149 [mm] sig_y_0 = 0.0000 [mm] sig_y_c = 0.23117 [mm] sig_y_T = 0.23117 [mm] L_x = 1.7617E+28 [1/cm**2 sec] n_x = 3.6258E+10 per beam (C)I_x = 1.9029E-03 [A] / bunch L_y = 1.7617E+28 [1/cm**2 sec] n_y = 3.6258E+10 per beam I_y = 1.9029E-03 [A] / bunch k_bunch = 1 tau_pol = 106.46 [min] tau_brems = 60666. [min] n_int = 2 pol_infinit. = 92.376 percent RF related parameters (for a total of 1 cavities): f_RF/f_0 = 1260 (D)volt._RF = 2.0000 [MV] f_RF = 412.74 [MHz] phi = 154.25 [degrees] Q_s = 1.3672E-02 f_synchr. = 4.4784 [kHz] (C)sig_buck. = 8.1199E-03 sig_s = 19.879 [mm] (C) tau_Q = 1.8245E+08 [min] shunt imp. = 0.0000 [MOhm/m] L_cavity = 1.0000E-03 [m] t_fill = 25.000 [microsec] (C)power = Infinity [MW] K_hm = 0.0000 [V/pC] (C)beta_RF = 1.0000 (C)psi = 0.0000 [degrees] (C)bucket = 7.8808 1NSLS-Booster-like lattice with 64 cells "MAD" Version: 8.51/15 Run: 19/04/06 23.03.48 NSLS-booster-like with 64 cells

  26. Some features of modified NSLS booster • Addition of defocusing quadrupoles to be able to cover an area in tune space • H-magnets with fields below 0.8 T • Magnets powered in many small groups • 1 Hz repetition rate suffices with pulse train injection • Extraction kicker 100 nsec flat-top (not a problem) • Extraction orbit bumps again can be in series

  27. NSLS II Tunnel

  28. NSLS II Tunnel

  29. NSLS II Tunnel

  30. Work for immediate future • Optimize booster (tracking, RF system, magnet power supply configurations, orbit control, ramping trims, etc.) for costing and engineering • Address the fear over booster fringing fields effects on main ring • Flesh out transport lines and get more definite spec’s for injection/extraction hardware • Showstoppers!!!! Are there any?

  31. Conclusion • Injection of NSLS-II can be done in several ways, we chose in-tunnel booster with full energy injector for IR ring for reasons of cost, reliability and efficiency of operation.

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