1. Managed by UT-Battelle for the Department of Energy Overview of Beam Instrumentations for High-Power Operation of the Spallation Neutron Source Saeed Assadi for SNS B.I. Group Beam Instrumentation Group Leaser SNS/ORNL

2. 2Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 OUTLINE  Overview of Beam Instruments  SCL Laser Profile Monitor Project  Recent results  Challenge  Future plan

3. 3Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 The Spallation Neutron Source

4. 4Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Liquid Hg Target SNS Accelerator Complex Front-End: Produce a 1-msec long, chopped, H- beam 1 GeV LINAC Accumulator Ring: Compress 1 msec long pulse to 700 nsec Ion Source 2.5 MeV 1000 MeV 87 MeV CCL SRF,  = 0.61 SRF,  =0.81 186 MeV387 MeV DTL RFQ RTBT HEBT Injection Extraction RF 945 ns 1 ms macro-pulse Current mini-pulse Chopper system makes gaps Accumulation 700 nsec Pulse

5. 5Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Interceptive Beam Instrumentation Systems RING 2 Wire-deleted RING 2 Wire-deleted SCL RTBT 5 WireScanners 1 Harp 1 RTBT Video Target Video RTBT 5 WireScanners 1 Harp 1 RTBT Video Target Video HEBT 5 Wire Scanners 2 BSM HEBT 5 Wire Scanners 2 BSM IDump 2 Wire 2 IDump Video IDump 2 Wire 2 IDump Video Edump 1 Wire Edump 1 Wire LDump 1 Wire LDump 1 Wire CCL/SCL Transition 1 Wire CCL/SCL Transition 1 Wire CCL 8 Wire, 4BSM, 1 Faraday Cup CCL 8 Wire, 4BSM, 1 Faraday Cup Operational MEBT 5 Wires D-box emittance D-box beam stop D-box aperture 1 fast faraday cup 1 faraday/beam stop D-box video MEBT 5 Wires D-box emittance D-box beam stop D-box aperture 1 fast faraday cup 1 faraday/beam stop D-box video DTL 5 Wire 5 Faraday Cup DTL 5 Wire 5 Faraday Cup

6. 6Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Non-Interceptive Beam Instrumentation Systems RING 2 Electron Profile Scanner 5 Electron Det. 12 FBLM 1 Beam in Gap Monitor 1 Tune, 84 BLMs, 4 NDs 2 Transverse feedback system RING 2 Electron Profile Scanner 5 Electron Det. 12 FBLM 1 Beam in Gap Monitor 1 Tune, 84 BLMs, 4 NDs 2 Transverse feedback system SCL 32 Position 86 Loss 9 Laser Wire 1 Laser Wire 24 PMT Neutron SCL 32 Position 86 Loss 9 Laser Wire 1 Laser Wire 24 PMT Neutron RTBT 1 Movable Harp 3 FBLM 26 BPMs 26 BLMs RTBT 1 Movable Harp 3 FBLM 26 BPMs 26 BLMs HEBT 29 Position 1 Laser Beam in- gap 1 Laser emittance sys 48 BLMs, 4FBLM HEBT 29 Position 1 Laser Beam in- gap 1 Laser emittance sys 48 BLMs, 4FBLM IDump 1 Position 1 Current 2 BLM IDump 1 Position 1 Current 2 BLM EDump 4 BLM, 1 BCM EDump 4 BLM, 1 BCM LDump 2 Loss 1 Wire,1 BCM 5 position LDump 2 Loss 1 Wire,1 BCM 5 position CCL/SCL Transition 2 Position 1 Loss 1 Current CCL/SCL Transition 2 Position 1 Loss 1 Current CCL 8 Neutron, 2 Thermal 48 Loss CCL 8 Neutron, 2 Thermal 48 Loss Operational MEBT 2 Thermal Neutron 3 PMT Neutron D-box Mode-lock laser 2 Beam-Gap Monitor [ChuMPS] 6 BPMs 2 BCMs 1 Mode-lock laser MEBT 2 Thermal Neutron 3 PMT Neutron D-box Mode-lock laser 2 Beam-Gap Monitor [ChuMPS] 6 BPMs 2 BCMs 1 Mode-lock laser DTL 2 Beam-Gap Monitor [ChuMPS] 3 Diff BCM Monitor 6 Thermal and 12 PMT Neutron 6 Current, 12 BLMs DTL 2 Beam-Gap Monitor [ChuMPS] 3 Diff BCM Monitor 6 Thermal and 12 PMT Neutron 6 Current, 12 BLMs Not Operating

7. 7Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Quick History and Facts about SNS The SNS is a short-pulse neutron source, driven by a 1.4 MW proton accelerator [ presently at.54 MW]. SNS will be the world’s leading facility for neutron scattering research with peak neutron flux ~20–100x ILL, Grenoble SNS construction project, a collaboration of six US DOE labs, was funded through DOE-BES at a cost of 1.4 B$ SNS will have 8x beam power of ISIS, the world’s leading pulsed source user facility, Stepping stone to other high power facilities, expected to achieve 1.4 MW in two years.

8. 8Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Motivation to Add &/or Modify More Beam Instruments  Improve reliability  Improve user friendliness – i.e. automation, additional features –  Support, diagnose “unexpected” events – i.e. Spark detectors, LEBT and RFQ RGAs  Accelerator Physics requests – Laser emittance system.  Allow “parasitic” studies; IPM, electron profile monitor. Different types of BLMs.

9. 9Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Continue: Motivation to Add &/or Modify More Beam Instruments  60 Hz Beam Accounting [Never was in the plan]  Low Energy Beam Loss Measurements, WGF4- A. Zhukov’s talk  Differential Current Measurements in DTL/CCL  High Power Operations.– e/p Instabilities, use of digital active transverse feedback system for the Ring. WG F- (wed) – Craig Deibele’s talk  Ring Electron Profile Monitor, BINP collaboration with SNS, initial results by W. Blokland in this talk.  Computation of Space-Charge Effects in Allison Scanner and Its Application to the Measurement of Emittance by Timofey Gorlov

10. 10Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Laser Striping Experiment SCL Laser Profile Monitors, 9-stations MEBT 3-D Laser Profile Monitor 1)MEBT Mode-lock laser initially in 1-D – 9/2004 2)SCL Nd:YAG 1064 nm Laser, 9-station – 9/2005 3)Laser Stripping test Nd:YAG, 3ed harmonic -- 8/2005 4)Working on making SCL Laser system turn-key -- to present ORNL-SNS Laser Diagnostic Activities 4M 4H 1D Laser Emittance

11. 11Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 What does the Laser do? Photo-neutralization Requirements High peak power Small spot size Transverse scan Temporal stability Detection h H-H- H 0 + e Cross-section is well known therefore stripping efficiency calculation is a matter of algebraic manipulation -H - time 12ns I beam

12. 12Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Principle of Laser Wire, direct electron current measurement at SNS. h H-H- N S Faraday Cup H0H0 e H0H0 Photodetachment Detected electron number is proportional to the ion density

13. 13Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Redundant Lasers are available for the SCL.  Q-switched Nd:YAG laser   = 1.06  m  f rep = 30 Hz, T w = 7 ns  E p = 50 – 200 mJ  Injection seeded  Timing synchronized to SCL Laser Room High pulse energy Small spot size Single wavelength Pointing stability Temporal stability Requirements:

14. 14Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 SCL 12345321712131415 250 m 227 m25 m160 m LR Laser room Laser wire station Cryomodule number Camera Mirror Power meter 32 LR Ring Layout of the SCL Laser Wire System CCLDTL Target MEBT 4 LW from 200 MeV 4 LW from 450 MeV 1 LW at 1 GeV

15. 15Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Q-switched Nd:YAG laser 1064 nm 30 Hz 7 ns Up to 1.5 J Injection seeded SCL Laser Transport Line

16. 16Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Schematic of Laser Wire Station Optics Mirror Lens Photodiode Beam Dump Flip-Mirror From LTL V-scan H-scan Ion Beam

17. 17Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Top-Level Software Controls all Stations and collects Data. Profile Measurement LW Station Diagnostics User specifies station, axis, scanning range/step/ave. number, controls timing, and data acquisition User monitors laser beam position, lens focus, electron collector output raw signal

18. 18Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 01234567891011121314 Magnet Current (A) LW Station 02 LW Station 15 LW Station 32 Falling edge cut Rising edge cut Normal profile Effects of LW Magnet Current

19. 19Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Vertical Beam Profile Measurement at LW32 12.9 12.4 11.9 11.4 10.9 10.4 9.9 9.4 8.9 8.4 7.9 7.4 Magnet Current (A) One challenge that is solved Effects of LW Magnet Current

20. 20Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Mini-pulse #1 #100 #200 #300 Advantage of Laser is to be able to scan the entire Macro-pulse.

21. 21Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Beam Profile Measurements LW1 LW5 LW9

22. 22Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Ion beam Laser beam f S Ion beam Yd Laser beam f S Laser beam shifts on the lens surface Laser beam shifts + Ion beam shifts from waist Realistic Laser Beam with respect to H-

23. 23Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Ion beam Yd Laser beam f S Challenge! Experimental Measurements Why do we get poor profiles in this case

24. 24Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Current Laser Wire Box 14 11.5 12 11.5 12 13.5 4.5 4  2.75  2-3/8  2.5  2-3/8 5.75 3.5 3.25 3.55 6.5 2.75 1 1 rearfront 6.75 7.25

25. 25Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Revised Laser Wire Box Design to Bring Larger Travel Range 14 11.5 12 11.5 12 13.5 4.5 4  2.75  2-3/8  2.5  2-3/8 3.25 3.55 6.5 2.75 1 1 6.75 7.25

26. 26Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 SUMMARY of Laser Profile Monitor  Profiles have been measured at all 9 stations  Operational parameters have been investigated and optimized  Software platform has been improved  Issues of radiation and stability are looked into and solutions are provided  Future plan –Secure system reliability –Optimize/document operational procedure –Identify technical problems and work on solutions

27. 27Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 600750 MCP Phosphor screen Photo camera Layout of the proposed EBP for SNS Accumulator Ring by BINP Electron Gun Deflector Quadrupole lens Proton beam Electron beam Transverse Profile Monitor

28. 28Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 28 Collaboration on Design and Construction of Electron Beam Profile Monitor Between SNS-ORNL and BINP, Novosibirsk, Russia has started Probe beam: Energy=75keV, Scan.-parallel, 3 rd,4 th quads - ON Proton beam: Energy=1GeV Np=1*10 13 Transverse size r=1.5cm Round uniform transverse distribution Simulation Blue line – theoretical profile, Magenta + square – reconstructed profile Alexander Starostenko

29. 29Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Horizontal Profile after 500 turn, 8 Micro-Coulomb of charge in the Ring.

30. 30Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Vertical Profile after 500 turn, 8 Micro-Coulomb of charge in the Ring ---- Another useful tool!

31. 31Managed by UT-Battelle for the Department of Energy WGF01- HB2008 8/26/2008 Thanks