Workshop Issues Heinz-Dieter Nuhn, SLAC / SSRL January 19, 2004

1. Workshop IssuesHeinz-Dieter Nuhn, SLAC / SSRLJanuary 19, 2004 • Workshop Overview • Discussion of the Commissioning Document Heinz-Dieter Nuhn, SLAC / SSRL

2. Introduction • Undulator commissioning has been discussed over the last several years • Many unsolved questions remain • Main challenges are • Radiation protection of magnetic material during commissioning and operation • Development of detectors that can withstand the heat load • Compilation of descriptions of detector types available for commissioning (both existing and under development) • Electron detectors upstream of the undulators • Electron and x-ray detectors along the undulator • Electron and x-ray detectors after the undulator • Decision on how to measure the FEL gain curve • Simulation support: Enhancement of existing codes to Include simulation of X-ray diagnostics Heinz-Dieter Nuhn, SLAC / SSRL

3. Workshop Focus • Commissioning of the Undulator Line of the LCLS with Beam • Prerequisites • Injector and Linac Commissioning Complete • Undulator, Diagnostics, Shielding, Beam Dump etc. in Place • Commissioning Without Beam for all Components Complete • Main Commissioning Tasks • Characterization of Electron Beam Up-Stream of Undulator • Establishment of a Good Beam Trajectory Through Undulator to Beam-Dump • Characterization of Spontaneous Radiation • Establishment of SASE Gain • Characterization of FEL Radiation Heinz-Dieter Nuhn, SLAC / SSRL

4. Goals • End-Of-Construction Goal • Required by DOE to close-off construction project (CD-4) • Needs to be simple to avoid project time and cost overrun • Commissioning Goal • Make LCLS ready for operation Heinz-Dieter Nuhn, SLAC / SSRL

5. Workshop Presentations • Charge – J. Galayda • Welcome – C. Pellegrini • Workshop Issues – H.-D. Nuhn • Status of Electron Beam Diagnostics – P. Krejcik • Status of X-Ray Beam Diagnostics along the Undulator – S. Milton • X-Ray Diagnostics after the Undulator – R. Bionta • Electron Beam Control and Alignment – P. Emma • Planning of FEL Simulations in Support of Commissioning • Commissioning Simulations using GENESIS 1.3 – S. Reiche • Commissioning Simulations using GINGER – W.M. Fawley • Summary and Final Discussion – J. Galayda Heinz-Dieter Nuhn, SLAC / SSRL

6. Expected Workshop Outcome • Resulting Document:“Beam Commissioning of the LCLS Undulator System”LCLS Tech Note • Target Date: Mid February 2004 • Purpose • Document Required for next DOE Review • Basis for Starting R&D for Commissioning Diagnostics Heinz-Dieter Nuhn, SLAC / SSRL

7. Draft Workshop Document • Title: Beam Commissioning the LCLS Undulator Systems • Acting Editor: James Welch • Authors: R. Bionta, P. Emma, W. Fawley, Z. Huang, P. Krejcik, S. Milton, H.-D. Nuhn, C. Pellegrini, S. Reiche, J. Welch, ??? • Available at Workshop WEB page.http://www-ssrl.slac.stanford.edu/lcls/undulator/meetings/2004-01-19_diagnostics_comissioning/ Many Thanks !!! Heinz-Dieter Nuhn, SLAC / SSRL

8. Draft Document: Table of Contents • 1. Introduction • 2. Goal of Commissioning • 3. Commissioning Procedure • 4. Radiation Characteristics • 5. Diagnostics • 6. Troubleshooting • A. Details: Electron Beam to Dump Heinz-Dieter Nuhn, SLAC / SSRL

9. Draft Document: 3. Commissioning Procedure • 3.1 Pre-Commissioning Status • 3.2 Electron Beam to Dump • 3.3 Beam-Based Alignment (BBA) • 3.3.1 BBA Procedure • 3.3.2 BBA Verification • 3.4 Commission FEE Diagnostics • 3.5 FEE Diagnostics Configuration • 3.6 Commission Undulator Diagnostics • 3.7 FEL Commissioning at Long Wavelength • 3.7.1 Trajectory Distortion Method • 3.7.2 Using Undulator x-ray Diagnostics • 3.7.3 Independently Removable Segments • 3.7.4 Variable Gap Undulator Heinz-Dieter Nuhn, SLAC / SSRL

10. Draft Document: 4. Radiation Characteristics • 4.1 Along the Undulator • 4.2 Downstream of the Undulator • 4.2.1 FEL • 4.2.2 Spontaneous Heinz-Dieter Nuhn, SLAC / SSRL

11. Draft Document: 5. Diagnostics • 5.1 Undulator Diagnostics Instrumentation • 5.2 Downstream X-Ray Diagnostics Intrumentation • 5.2.1 Diagnostics in the FEE • 5.2.2 Diagnostics in the Commissioning Diagnostics Tank • 5.2.3 Total Energy • 5.2.4 Pulse Length • 5.2.5 Photon Spectrum • 5.2.6 Transverse Coherence • 5.2.7 Spatial Shape and Centroid Location • 5.2.8 Divergence Heinz-Dieter Nuhn, SLAC / SSRL

12. Related Document in Preparation • Title: Undulator Protection Study • Authors: E. Bong, P. Emma, P. Krejcik, H.-D. Nuhn, J. Welch • Expected Completion: Early March 2004 Heinz-Dieter Nuhn, SLAC / SSRL

13. FEL Gain Measurement • Desirable measurement s as function of position along undulator : • Intensity (LG, Saturation) • Spectral Distribution • Bunching • Alternative measurements of saturation at undulator end: • Intensity vs. Peak Current • Intensity vs. Emittance Saturation Exponential Gain Regime Undulator Regime 1 % of X-Ray Pulse Electron BunchMicro-Bunching Heinz-Dieter Nuhn, SLAC / SSRL

14. Measurement of SASE Gain along the undulator • Direct: Put Detectors in the Breaks between Undulator Segments. No good solution for x-ray detector in existence, yet. • Alternative: Characterize x-ray beam at single station down stream of undulator after gain is turned off at a selectable point along undulator by • introduction of orbit distortion. (Initial studies by Z. Huang) • removal of undulator segments (Changed Design) • opening of gap if undulator is variable gap device. (Changed Design) Heinz-Dieter Nuhn, SLAC / SSRL

15. Gain Measurement Scenarios (Reichanadter) • Full Diagnostics Between Undulators • Plusses: Allows Commissioning with all undulators in place • Minuses: Does not Address Radiation Damage Issues. Most Expensive Option in Terms of $ and Resources • Variable Gap Undulators • Plusses: Addresses Radiation Damage Issue. Allows Commissioning with Single Suite of Diagnostics Downstream of the Undulator. Cost Neutral with respect to Full Diagnostics • Minuses: Redesign of Undulator to Incorporate Variable Gap Function. Might Decouple Quads from Undulator. • Translatable Undulators • Plusses: Addresses Radiation Damage Issues. Allows Commissioning with Single Suite of Diagnostics Downstream of the Undulator. Much Cheaper. • Minuses: Decouples Quads from Undulator. Movers more complicated but doable. • Trajectory Distortion • Plusses: Allows Commissioning with All Undulators in Place • Minuses: Does not Address Radiation Damage Issues. Much Cheaper. Subject to Feasibility Study. Heinz-Dieter Nuhn, SLAC / SSRL

16. Commissioning Phases • Phase 0: Beam Through Undulator (at 0.2 nC, sngl shot) • Phase I: Spontaneous Radiation (at 0.2 nC, 10 Hz) • Parameters: Energy 4.45-14.1 GeV, Emittance: not critical • Goals: Establish straight and stable trajectory, measure spontaneous radiation • Phase II: Low Energy FEL Radiation (at 0.2-1 nC, 10 Hz) • Parameters: Energy: 4.45 GeV, Emittance: < 4 microns Peak Current : < 1 kA • Goals: Characterize FEL radiation. Achieve saturation. • Phase III: High Energy FEL Radiation (at 0.2-1 nC, 10 Hz) • Parameters: Energy: >4.45 -14.1 GeV, Emittance: 1.2- 4 microns Peak Current : 1-3.4 kA • Goals: Characterize FEL radiation, gain. Achieve saturation. Heinz-Dieter Nuhn, SLAC / SSRL

17. Conclusions • Workshop Goal is to provide input to prepare a document describing the commissioning of the LCLS undulator with beam. • Main Issues are: • Definition of a Commissioning Procedure that provides Undulator Radiation Protection • Selection of a Method for Measuring Radiation Properties along Undulator • Multiple Detectors Positioned Along Undulator • Gain Termination through Trajectory Distortion • Removable Undulator Segments • Variable Undulator Gaps • Definition of R&D Program for Diagnostics Components • Code Development to Support Commissioning • Time is short – Quite a number of questions remains unanswered Heinz-Dieter Nuhn, SLAC / SSRL

18. End of Presentation Heinz-Dieter Nuhn, SLAC / SSRL