NSLS-II Accelerator System Advisory Committee Review Diagnostics Design and R&D

1. NSLS-II Accelerator System Advisory Committee Review Diagnostics Design and R&D Om Singh – Group Leader July 17-18, 2008

2. Outline • SR Diagnostics Hardware -- Layout & Locations • RF BPM Resolution Requirements – Various time scale • Standard RF BPM • Insertion Device RF BPM • RF BPM Electronics Evaluation • Pin-hole Camera Resolution Simulation • Near Term Plan • Summary

3. SR Cell Diagnostics Systems – BPM & Beam Loss Monitors C) X-ray BPMs – up to 2 / FE D) Slow & Fast Correctors 3PW or BM B-Line ID Beamline SC FC FCFCFC SC BPM BPM BPM BPM BPM BPM BPM BPM B) Small Gap RF BPMs  2 or 3 per Cell; Button Assembly on a Stand or ID Chamber A) Standard Gap RF BPM  6 per cell E) Beam Loss monitor (Location TBD)  p-i-n diode detector ; 2 per cell  scintillation detectors; 10 total F) RF PUEs  2 total for top-off

4. SR Diagnostics Hardware Locations - Preliminary Odd Cells Even Cells

5. NSLS-II Lattice Functions & Electron Beam sizes / divergences Lattice Functions Electron Beam Sizes & Divergences Most challenging Beam stability Requirements = ~ 0.31 μm

6. NSLS-II SR RF BPM System – Performance Requirements* * Requirement values are preliminary - work in progress ** ID BPM system resolution values will be smaller ( factor of ~ 0.5) *** @ 5 mA – 50 mA stored beam, BPM receiver resolution values will be worse (factor of ~2) (Req. met - Test Data Later)

7. BPM Evaluation - Baseline Design • Baseline Design (one button/flange) • Consists of one 10 mm dia. button w 34 mm flanges • ~ 28 mm horizontal separation & ~ 25 mm vertical aperture • Matlab Simulation  input power level @ 500 mA= - 2 dBm (OK) • Sx =~ 0.12 / mm ; Sy =~ 0.04 / mm (low) • Electronic Resolution in frequency band 0.017 – 200 Hz •  H-Resolution=~ 100 nm ; V-Resolution =~ 300 nm Baseline Design (28x25) SY=~0.04 SX=~0.12

8. BPM Evaluation - Proposed Design • Proposed Design • (two button/flange) • Consists of two ~7 mm dia. buttons on a single 50 mm dia. Flange; with ~16 mm H-separation (vertical aperture remains same - 25mm) • Two buttons on a flange reduces total flange counts & makes survey/ alignment process easier • 7 mm button (over 10 mm) is also favored for beam heating issue A A 50 16 25 2

9. BPM Evaluation - Proposed Design (cntd) • Proposed Design (two button/flange) • Matlab Simulation shows •  input power level @ 500 mA = -8 dBm (OK) •  Sx =~ 0.09 / mm ; Sy =~ 0.09 / mm (OK) • Electronic Resolution in 0.017 – 200 Hz BW •  H-Resolution =~ 135 nm • V-Resolution =~ 135 nm (200 nm reqd) Resolution vs Input Power Resolution SY=~0.09 SX=~0.09 -8 dBm

10. Flange Layout – 7mm buttons

11. RF BPM Button • Button Heating NSLS-II Accelerator Technical Review Instrumentation and Diagnostics August 9-10, 2007 Report of the Review Committee submitted September 28, 2007 • Findings, recommendations and comments: • Button block cooling issues should be addressed, including block distortion and the possible compromise of Helicoflex flex gasket integrity due to beam heating from trapped modes (Diamond experience). • A smaller button diameter should be considered to reduce button heating and impedance (look at the ALBA paper submitted to the 2007 DIPAC).

12. RF Button Heating Mini-Workshop at EPAC (June,2008) • Organized by Soleil/NSLS-II - attended by experts from NSLS- II, KEK, Soleil, Diamond, PEP-II, ESRF, PETRA-III, SLS, SPEAR3, Bergoz & Others. • Presentations from NSLS-II, Soleil, Diamond, ESRF • Measured temperatures of connector pin on ambient side • in the range of 60oC @ ESRF • in the range of 100oC @Diamond • suggesting buttons themselves may be considerably hotter (~ several hundred oC) • Estimated power at Diamond (from both GdfidL and temperature measurements) is ~5W/button, distortions/ position drifts are large ~10 microns • Scaling to NSLS-II parameters suggests to do initial Ansys analysis with ~3W/button

13. RF Button Heating mini-Workshop at EPAC (June,2008) (cntd) • Agreement on mechanism of heating – hi Q trapped mode in transmission line formed by outer circumference of button and inner surface of housing. • Diamond results suggest - do initial Ansys analysis with 3W/button to get thermal distribution/distortion – this is in progress • Soleil simulations suggest - adjust button thickness and gap to wall to change transmission line impedance • Gdfidlsimulation - Kloss factor as thickness • 0.012 V/pc @ 2 mm; 0.007 V/pc @ 5mm • Repeat the analysis with “Microwave Studio” simulation • Ongoing communication/collaboration with other labs

14. ID BPM Button - Baseline Design Established Design – used at APS & Elettra Flanges mounted on top & bottom of Small gap Chamber ~10 mm ~70 mm Two 4 mm Dia buttons HS = 10 mm • Baseline design provides adequate sensitivity – SX=0.26; SY=0.14 • Detail button heating analysis needs to be done with NSLS-II beam • Two configurations of ID BPMs are proposed • Normal configuration - uses a low thermal expansion stand for stability • Alternate configuration – buttons mounted on ID chamber, when • adequate space is not available for bellows, transitions and stand.

15. Sensitivity Optimization – Rotated Flange Sensitivity vs H-separation • Vertical sensitivity will be further optimized by rotating the 2-button flange, if needed • Effects of longitudinal displacement of buttons needs to be analyzed Rotated Un-Rotated

16. Calibrator Set-up • Confirm transfer function calculations • Use single wire to simulate beam current; mounted on two motor controlled assemblies. • Use two 34 mm dia. flanges; mount on a large flange to adjust H-separation by rotation • Explore interaction between beampipe modes and button resonance • Evaluate BPM electronics • Develop beam simulator – Possible Collaboration with SLAC • Evaluate position and fill pattern dependencies – critical for top off operation

17. ID-BPM Stable Support Specification  Total Thermal expansion < 100 nm R. Alforque • BPM assembly – • has 3 invar rods for alignment • small gap vertical aperture & 4 mm • dia buttons for optimizing sensitivity • Standard size flange at each end 10” Dia Carbon fiber composite stand limits thermal expansion to 20 nm/m/0.1oC

18. ID BPM Support Thermal Stability • Position Stability Requirement for User BPMs is 100nm vertical • Temperature stability spec for the tunnel is +/- 0.1C • Need to verify that support post meets spec • Build a fiducial structure using additional low TEC posts (next slide) • Thermally isolate the fiducial, and give it lots of mass (t ~ 1 week) • Thermally isolate the test post, use heaters to vary temperature (t ~ 1 hour) • Use capacitive and DVRT sensors to measure length variations • Status • DAQ, some position sensors, and some temperature sensors in house • POs for remaining position and temperature sensors have been written • Shop fabrication of the test stand is underway

19. ID-BPM Support Test Set-up • Notes: • All components to be wrapped with insulating blankets wherever possible • 2. 3/16” sstl rods in tension will support the central tube • 3. All materials sstl other than the carbon fiber tubes • Indicates Pt temp sensor • Indicates TC temp sensor ~48” ~48” at both endsmeasure relative displacement due to temperature variation

20. RF BPM Electronics -Proposed Studies • Long term stability (for centered and off-centered beams) • Measure dynamic range • Dependence on ambient temperature • Fill pattern dependence (including different envelopes) • Dependence on RF frequency • Effects of cable length mismatch • Noise spectrum • Explore for “dangerous” frequencies • Signal pre-processing • Establish acceptance test requirements

21. Stand for Stability Test for Libera Brilliance • RF frequency can be modified by external clock • Chosen configuration provides phase locking between carrier and beam envelope • Arbitrary waveform generator - provides amplitude or phase modulation/ trigger pulse modulation • Temperature is monitored with platinum PT-100 probe using Digital Multi-meter External Clock Reference 10 MHz Repeater system clock Libera Brilliance Func. Generator Gated Oscillator machine clock A B C D 4-way Splitter Attenuator 500 MHz Attenuator Attenuator Attenuator

22. First Results from the Libera Tests – Meet Drift Spec. TEMP ~ 1 oC TEMP HOR ~ 200 nm HOR 7 Hrs VERT ~ 100 nm VERT • Power level 6 dBm (0 dBm at each input) • 80% fill (2 μs pulse duration with 2.62 μs pulse repetition rate) • Temperature Drift 200 nm /°C

23. Pinhole Camera with 3PW Source Three-pole wiggler Tungsten Pinhole Attenuator Mirror CdWO4 scintillator Al window Bending magnet Camera L1=3 m L2=15 m 3PW has higher magnetic field (1.14 T) than dipole. Shorter critical wavelength provides better spatial resolution. Large vertical β-function (21 m) gives large beam size (12.4 μ). Horizontal beam size is defined predominantly by energy spread (σE/E·η=170μ) rather than emittance (1nm·4.1m)½=64μ. Attenuator reduces heat load on elements and serves as high pass filter for synchrotron radiation. Estimation of resolution is done using MATLAB script. • Achievable resolution of 5.2 microns is sufficient for reliable measurement of vertical beam size (12.5 microns for 8 pm emittance) • Image of the beam is magnified by factor 5 and loss of resolution due to phosphor is of less importance)

24. Near Term Plan • Complete detail RF button heating analysis • Prototype two-button/flange BPM & test • ID-BPM support procurement in process • Design & build test set-up to measure support • thermal stability • Integrate & test BPM calibrator set-up with computer control • Develop program to evaluate/ compare BPM electronics

25. Summary • Location of bpms and diagnostics hardware have been identified • SR BPM resolution requirement table vs time scale in progress • New button design in progress for standard RF BPM • Heat issues are being addressed for standard & ID BPMs (RF) • ID-BPM support design is complete; Procurement is progress • ID-BPM support thermal test set-up designs in progress • ID-BPM calibration test set-up complete; Integration to follow • Pin-hole diagnostic beamline design analysis in progress • Near term plan has been identified

26. Acknowledgements R. Alforque, A. Blednykh, A. Broadbent, P. Cameron, B. Dalesio, L. Doom, R. Heese, G. Ganetis, D. Hseuh, E. Johnson, S. Kramer, F. Lincoln, R. Meier, I. Pinayev, J. Rose. S. Ozaki, S. Krinsky, B. Mullany, V. Ravindranath, S. Sharma, J. Skaritika, T. Tanabe, T. Shaftan, W. Wildes, F. Willeke, L.Y. Yu.

27. Backup Slides

28. Diagnostics System Hardware Layout Short straight section – 11-ID e- ~1 m DCCTStriplineSCW Dipole (BM-A) QL3 SL3 QL2 SL2 QL1 Dipole (BM-B) e- 4 diagnostics hardware slots at 3 PW locations Cell # 26-29

29. courtesy Alexei Blednykh

30. courtesy Alexei Blednykh

31. Loss factor and Power Loss Iav=500mA, T0=2.6e-6m

32. Partial Compilation of Relevant Parameters color code: yellow – NSLS-II options red – danger of physical damage purple – thermal distortion due to heating