1. Characterization of Fast Orbit Feedback System Om Singh, APS, ANL NSLS-2 Beam Stability Workshop BNL, April 18-20, 2007

2. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 2 Outline Bpm & Magnet Layout – One SR Sector AC Beam Stability  Goals & Present Performance Orbit Feedback Sub-systems  Resolution & Responses  Digital Process Rate & Orbit Correction Configuration Summary & Upgrade Plans Photo

3. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 3 27.6 Meters Number of sectors = 40 Circumference = 1104 m Transverse Tunes ν x = 36.2, v y = 19.27 Energy = 7 GeV Beam Current = 102 mA RF Frequency = 352.194 MHz Revolution Frequency = 271.554 KHz Harmonic number = 1296 One Sector of the Advanced Photon Source Storage Ring

4. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 4 Beta Functions

5. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 5 X-Ray Beam Position Monitors  Photo -emission sensory blades  Excellent thermal insulation and vibration damping  Beam Position Measurement BW up to Tens of KHz One Sector - Cartoon Bending Magnet Slow Correction Magnet Fast Correction Magnet Monopulse BPM – turn by turn (AM/PM)  Up to 8000 turn-by-turn samples of beam history - @ ~ 271 KHz  Averages to 50 Hz, 2 Hz, 0.03 Hz BW Sector N Narrowband (Switching) BPM  Small Bunch Pattern & Intensity Dependence (vs Mp bpm)  High Reliability and easy maintainability  Beam Position Measurements BW up to ~ 5KHz Elliptical Chamber PUEs ID Chamber PUEs ID Device Beam Position Monitors and Dipole Magnets

6. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 6 AC Beam Stability Goals SR Emittance ε e = 3.1 nm; coupling = 0.8% 1.Presently σ x = 280 μm; σ y = 10 μm; σ’ x = 12 μrad; σ’ y = 3 μrad Beam stability goal and present performance 1.Stability goal* (AC)  5% of the APS beam size/ divergence Goal / Present Performance x, y (μm rms ) x’, y’ (μrad rms ) Goal (0.017 – 200 Hz)  14.0, 0.5 0.60, 0.22** Present (0.017 – 200 Hz)  6.0, 2.0 0.26, 0.34 Broadcast (0.017 – 30 Hz)  0.8, 0.6 *G. Decker presented to 2005 DOE-BES Review at APS ** Includes photon divergence contribution, 7 th harmonics, APS undulator A

7. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 7 AC Stability @ ID’s Sources 4 um 1.5 um Correction BW

8. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 8 AC Pointing Stability @ ID’s Sources * G. Decker – DOE-BES Review 2005 220 nrad Spec

9. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 9 Global 1.5 KHz Processing Architecture 20 Double Sector Processors 1 Master Processor 1 IOC Processor (Datapool) Reflective Memory Network

10. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 10 Orbit Feedback - Subsystems Subsystems & Performance Limiting Factors 1. BPM/ Corrector - Resolution 2. BPM/ Corrector - Responses 3. DSP Processing Power - Process Rate & Orbit Correction Configuration

11. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 11 Beam Motion @ ID Source vs Bpm Resolution (Noise) Cumul RMS 30 Hz band (H & V) Beam Motion = 0.8 & 0.6 micron RfBpm Noise = 0.3 & 0.35 micron  Faster digitization should lower noise floor XBpm Noise = 0.04 & 0.04 micron  Low noise level, but so far only in DC orbit feedback Digitizer Noise = 0.01 & 0.01 micron 30 Hz Band

12. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 12 BPM / Fast Corrector – Responses BPM Response One pole low pass filter @ 2KHz Fast Corrector Response One pole low pass filter @ 1.5 KHz Delay ζ = 0.2 ms BPM & Fast Corrector Combined Phase Contribution @ 100 Hz = 15 o @ 200 Hz = 27 @ 300 Hz = 45 @ 400 Hz = 57 @ 500 Hz = 70

13. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 13 Orbit Feedback - Limitations  Digital Signal Processor - Present hardware allows to process up to 1.5 KHz sample rate – limits orbit correction BW to 50-90 Hz Up to 4 Bpms per sector are included due to processing time constraint Study in progress to include Xbpms  Corrector Only one corrector (A3) available with fast response – limits orbit correction A second fast corrector is required for optimal orbit correction – simulation shows further noise reduction by ~ 2.5 RFBpms XBpms Fast  Corrector

14. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 14 Optimized Overall O. L. Responses (Vert) – 1.5 KHz vs 15 KHz Optimized parameters @ 1.5 KHz s.r. Digital Process Rate = 1.5 KHz  Digitization Phase = (f/fs) * (360deg) Regulator  1 HPF @ 0.07 Hz  1 LPF @ 25 Hz  Gain = 4 Orbit Correction Bandwidth  100 Hz Optimized Parameters @ 15 KHz s.r. Digital Process Rate = 15.0 KHz  Digitization Phase= (f/fs) * (360deg) Regulator  1 HPF @ 0.105 Hz  1 LPF @ 75 Hz  Gain = 6 Orbit Correction Bandwidth  400 Hz o Unit gain line

15. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 15 Summary – Stability Goals, Status & Plans Beam Size/ Divergence Stability Goals Stability Status Meet Goals (yes/no) x µm146.0yes y µm0.52.0no x’ µrad0.60.25yes y’ µrad0.220.35no Proposed Upgrade Plans Add 2nd fast corrector per sector - simulation shows noise reduction factor is 2.5 Increase process rate ten-fold > 15 KHz - AC obit correction BW to 400 Hz Improve RfBpm noise floor – increase digitization rate Include Xbpms in fast orbit feedback AC Beam Stability (0.017 – 200 Hz) - Horizontal beam stability goals are met - Vertical beam stability requires a factor of ~ 4 improvement

16. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 16 Bpm/ Corrector In-Use Status – Orbit Feedback RFBPMsRFBPMs Xbpms Fast Corr  Configuration Layout – L. Erwin HorizontalVertical

17. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 17 Photo

18. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 18 In Tunnel BPM Hardware (Rf Bpms) Elliptical Chamber Buttons & Matching Networks Filter & Comparator Small Gap Chamber Buttons Photo – M. Hahne

19. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 19 In Tunnel BPM Hardware (Xbpms) * Deming Shu -APS Xbpm Main Assembly X-Y Translation Stages Mounting Stand Xbpm Blades Assembly

20. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 20 BPM Front-End Electronics and Processors – Two Sectors  Patch Panel  Pre-Amps  Filters &Controls Narrowband RFbpms  AM/PM RFBpms  FDBK Processors  BPM IOC  16 Bits ADCs X-ray BPMs Interface RF Bpms & Processors Photos by M. Hahne Outside Tunnel Hardware

21. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 21 Acknowledgement To All APS members for contribution to support ongoing Beam Stability work

22. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 22 BPM Hardware Development Highlight RF Bpms 1.Mpbpm data acquisition* upgrade in progress, using fast 88 MHz A/D and FPGA technology; can provide bunch by bunch position data 2.Evaluation of yet another kind BPM in progress from Instrumentation Technology (Libera) – ALL digital bpm with direct sampling of each button RF signals. Two units are in hand & evaluation with beam to follow Photoemission type - Xbpm 1.BM Xbpm – extremely reliable; used in DC Orbit control routinely 2.ID Xbpm – “Decker distortion” has been completed redirecting unwanted stray radiations away from ID radiations. Provides beam measurement to sub-micron level at fix gap. When gap varies, photon beam measurement held to tens of microns with feedforward algorithm Xbpm – hard X-ray type Bpm under development; to resolve to sub-micron level even with ID gap change; has potential for beamline alignment gold standard

23. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 23 (G. Decker)

24. Characterization of Fast Orbit Feedback System – APS, ANL Om Singh NSLS-2 Beam Stability Workshop, April 18-20, 2007 24 * G. Rosenbaum & G. Decker *