BROOKHAVEN SCIENCE ASSOCIATES NSLS-II Injection System T. Shaftan NSLS-II Accelerator Systems Advisory Committee October 11, 2006

BROOKHAVEN SCIENCE ASSOCIATES Contributors I. Pinayev, J. Rose, J. Skaritka, R. Heese, C. Stelmach, S. Pjerov S. Sharma, L.H. Yu T. Shaftan G. Ganetis, D. Hseuh, N. Tsoupas, W. Meng, J. Beebe-Wang, A. Luccio, D. Raparia D. Wang J. Safranek, L. Emery, W. Joho

BROOKHAVEN SCIENCE ASSOCIATES Outline NSLS-II injection requirements Considerations for injection system Injection straight arrangement and simulations Low energy accelerator Booster Transport lines Concluding remarks

BROOKHAVEN SCIENCE ASSOCIATES Requirements for NSLS-II Injection High reliability Reasonable fill speed Low losses Low power consumption Lifetime 3 hours (with 3 rd HC) Top-up  Stability of current <1 %  Time between top-up injections >1 min  Bunch-to-bunch variations of charge <20% Ī t Ī t QIQI t IbIb bunch #

BROOKHAVEN SCIENCE ASSOCIATES Ring parameters related to injection ParameterValue Energy, GeV3 Circulating current, A0.5 Circumference, m780 Revolution period,  s 2.6 RF frequency, MHz (wavelength, m)500(0.6) Circulating charge,  C 1.3 Total number of buckets1300 Number of filled buckets 1300  4/5  1040 Charge per bucket, nC1.25 Lifetime, hours3 Interval between top-up cycles, min1 Current variation between top-up cycles, %0.55% Charge variation between top-up cycles, nC7.15

BROOKHAVEN SCIENCE ASSOCIATES Injection Scenario N M = Injected bunch train # Ring bunch pattern t t 1 st turn2 nd turn3 rd turn IbIb  kicker Many (~1000) bunches in the ring  multi-bunch injection  N M bunches in injected train  Filling N M consecutive buckets in the ring  Sequentially shift injection timing 1 Hz repetition rate suffices with pulse train injection 1 minute between top-up cycles Kickers duration can be 2 turns long (5  sec) or even longer Considered in ALS top-up (10 bunches)

BROOKHAVEN SCIENCE ASSOCIATES Injection straight design Ring Injection Kickers (4) Field, T0.193 Length, m0.75 Angle, mrad14.4 Current Amplitude, kA5.34 Voltage, V4500 Temporal shape5 μsec ½ sine wave Pre-septum magnet Field, T1.1 Length / Angle, m / mrad0.75 / 83 Peak current/voltage, kA/kV12/0.6 Pulse shape100 μsec ½ sine wave Final Injection Septum Field, T0.9 Length / Angle, m / mrad0.5 / 45 Peak current/voltage, kA/kV10/0.6 Pulse shape60 μsec full sine wave I. Pinayev and R. Heese

BROOKHAVEN SCIENCE ASSOCIATES Requirements on Ring Stay-Clear Tracking is done with TRACY-2 Tracking a set of particles corresponding to injected beam Tracking for 500 turns Beam envelope is recorded at every ring turn on every element Tracking for 10, 50, 100 nm Black envelope: scaled septum aperture for horizontal Scaled undulator gap for vertical Conclusion: stay-clear required for injection can be easily met J. Rose, I. Pinayev and J. Bengtsson

BROOKHAVEN SCIENCE ASSOCIATES NSLS-II injector Linac 200 MeV Th. Gun 100 keV 3 GeV

BROOKHAVEN SCIENCE ASSOCIATES Low-energy accelerator Specifications for NSLS-II linac: Energy 200 MeV, energy spread <0.5% RMS, emittance ~100 nm at 200 MeV Defined by small vacuum chamber in the booster Soleil linac:  10 nC in 300 ns at 100 MeV  Energy spread <0.5% RMS  Emittance ~40 mm mrad  Beam loading compensation Fits NSLS-II requirements Turn-key system Soleil linac Measured bunch train along the linac from: A. Setty et al., Commissioning of the 100 MEV …

BROOKHAVEN SCIENCE ASSOCIATES Layout of 200 MeV linac 5 linac sections 3 klystrons With loss of one klystron: 177 MeV J. Rose

BROOKHAVEN SCIENCE ASSOCIATES Linac-to-booster Transport Line Length: 19 meters 2 dipoles, 8 quadrupoles, 4 correctors Energy spectrometer Safety shutter Flags, BPMs Loss monitors Diagnostics set-up sufficient for commissioning of the linac I. Pinayev

BROOKHAVEN SCIENCE ASSOCIATES Booster: design considerations “Compact” booster“Same tunnel” booster Building and shielding are very expensive Higher cost for vacuum, diagnostics Ability to commission booster in advance OK, based on the SLS experience Ability to service and troubleshoot without beam interruption Lifetime is 3 hours  Average hardware failure leads to stop anyway “Conventional” designHigher beam quality, relaxed tolerances

BROOKHAVEN SCIENCE ASSOCIATES Booster location Mounting on the ceiling  No expanding tunnel  No transport lines blocking tunnel pathway  No magnets above ring straights  No water-cooling for magnets  Cross-talks?

BROOKHAVEN SCIENCE ASSOCIATES Booster parameters ParameterNSLS-IISLS Energy range [GeV]0.2 – – 2.4 Circumference,[ m] Emittance [nm]11.59 Repetition rate [Hz]13 Radiation loss per turn [keV] RF frequency [MHz]500 Magnet power [kW] RF voltage [MV] RF acceptance [%] 11  0.43 Beam current [mA]31 Momentum compaction5.7· ·10 -3 Tunes [x / y]19.19 / / 8.38 Chromaticity [x/y]–21.7 / –21.7–15 / –12 Damping times [ms] (x / y / E)22 / 31 / 1911 / 19 / 14

BROOKHAVEN SCIENCE ASSOCIATES Booster lattice Dynamic Aperture Modified NSLS booster lattice 60 combined function dipoles 90+6 quadrupoles sextupoles 60 X-Y correctors 75 BMPs for orbit correction, rms orbit < 1mm Dipole field 0.7 T at 3 GeV Large dynamic aperture Negligible eddy current effect at 1Hz

BROOKHAVEN SCIENCE ASSOCIATES Booster magnets Magnets are located above storage ring Use of air-cooled coils Small size of vacuum chamber  small magnet size and weight Small power consumption Relaxed tolerances on magnet alignment and field errors Simple design of support hangers Quadrupoles and sextupoles: standard and compact design

BROOKHAVEN SCIENCE ASSOCIATES Booster Magnet Power Supplies and RF In series circuits:  B-PS – 60 dipoles  Q1-PS – 60 quadrupoles  Q2-PS – 30 quadrupoles  SF-PS – 15 sextupoles  SD-PS – 15 sextupoles Separate circuits:  60 horizontal trims  60 vertical trims  3 x 2 quadrupole trims All power supplies can operate at 1 Hz Programmable ramping profiles Synchronization from line voltage G. Ganetis J. Rose RF voltage ramps to 1 MV Energy acceptance 1% at 3 GeV Total RF power 37 kW Single 5-cell PETRA cavity Capable of delivering 1.5 MV IOT transmitter 80 kW at 500 MHz

BROOKHAVEN SCIENCE ASSOCIATES Booster vacuum Target average value 1E-7 Gas-scattering losses throughout energy ramp  0.5% Vacuum chamber provides with > 10xRMS beam sizes in both planes 2 sizes of vacuum chamber:  20x30mm 2 in dipoles  25x40mm 2 in dispersive straights 5 pumps per superperiod = 150 pumps total Pumps in RF and injection/extraction straights D. Hseuh

BROOKHAVEN SCIENCE ASSOCIATES Booster-to-Storage ring Transport Line Consists of 3 parts –Horizontal achromat –Vertical dogleg –Horizontal achromat Doublets for optimizing  -functions without disturbing  -functions Maintain small beam size along the transport line Magnets / diagnostics:  4 dipoles,  17 quadrupoles,  6 trims,  6 BPMs, 6 flags, 2 ICTs C. Stelmach, S. Pjerov

BROOKHAVEN SCIENCE ASSOCIATES Concluding Remarks We designed reliable and robust NSLS-II injection system Conceptual design of NSLS-II injector  Linac will be purchased, turn-key + some R&D?  “Same tunnel” booster  Transport lines: sufficient diagnostics for step-by step commissioning Storage ring:  Sufficient dynamic aperture for injection  Sufficient stay-clear for injection  Injection kicker system will be purchased, turn-key Future work:  Optimization of injector design/cost  tracking in realistic scenario,  injection tolerances  Consider Lambertson septum