1. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 Radiation Damage Study at FLASH using the Diagnostic Undulator J. Pflüger, J. Skupin, B. Faatz, Y. Li, T. Vielitz DESY, Hamburg

2. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 Overview The FLASH Diagnostic or “Sacrificial” Undulator Dose Measurements Observed Demagnetization TTF1 Results Revisited FEL Damage Theory and Simulations Life expectancy Conclusions

3. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 The Diagnostic Sacrificial Undulator

4. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008

6. Radiation Dose Measurements

7. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008

8. 12 / 2004 - 4 / 2008

9. Measurement

10. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 Demagnetization Measurements

11. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008

14. TTF1 Results (1999-2002) Revisited J. Pflüger, B. Faatz, M. Tischer, T. Vielitz NIMA 507 (2003), 186,

15. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 TTF1 Undulator System 1999-2002 1999 On Axis Collimator System From: J. Pflüger, B. Faatz, M. Tischer, T. Vielitz NIMA 507 (2003), 186,

16. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 FLASH Collimator System Well separated Axes of Accelerator and Undulator (300mm) Provides Phase Space and Energy Collimation Apertures fully integrated into Dogleg Collimator does not shine into Undulators Very effective for radiation protection 0.3m

17. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 FLASH: Three representative weekly dose readings 12 / 2004 - 4 / 2008 Sacrificial Undulator

18. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 Field Difference Before-After Installation Positions of Focusing Magnets for the FODO Lattice (In Total 10) Conclusion: No detectable Radiation Damage up to 12000Gy

19. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 TTF1 Revisited Model for Dose Symmetric Parabola Observed Difference proportional to Dose Demagnetization Results: 2 x 10-4 / kGy Test Undulator at FLASH: 5 x 10-4 / kGy

20. XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Joachim Pflueger, DESY STI Presentation October 10, 2007 Undulator Errors and FEL Performance Yuhui Li, Bart Faatz Joachim Pflüger Reference: Y. Li, B. Faatz, J. Pflueger, Proceedings of the FEL07 Aug 26-31 Novosibirsk, Russia FEL Simulations

21. Joachim Pflueger, DESY STI Presentation October 10, 2007 XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Traditional: Tolerance Estimation using the Pierce Parameter Very stringent requirements on undulator precision and temperature stability 2ρ2ρ Resonance condition: Δ g < 1 μm ΔT < 0.08°C For XFEL SASE FEL bandwidth If this criterion is fulfilled no gain degradation is expected!

22. Joachim Pflueger, DESY STI Presentation October 10, 2007 XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Phase shake --- correlation to power degradation Field calculated for different periodic errors Power Loss calculated by GENESIS 1.3 RMS Phase shake calculated by formula SASE1  depends on K 0, u and error geometry  = 39.7 rad/m for u =35.6mm, K 0 = 3.3 and sinusoidal error function Periodic Field Error  : Error period length GENESIS 1.3

23. Joachim Pflueger, DESY STI Presentation October 10, 2007 XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Phase shake analytical calculation For all of the four errors analyzed, For the same phase shake (same power degradation), large error period means small error strength. Vice versa… if the error period is small, large error strength (larger than ρ) is permitted λδ1λδ1 …… = λ δn z K ΔK λδ1λδ1 λδ1λδ1 …… = λ δ z K ΔK λδ2λδ2 λδ1λδ1 λδ2λδ2…… = λ δ z K ΔK λδ1λδ1 …… = λ δn z K ΔK λδ2λδ2 λδ3λδ3

24. Joachim Pflueger, DESY STI Presentation October 10, 2007 XFEL The European X-Ray Laser Project X-Ray Free-Electron Laser Girder Deformation as a periodic sinusoidal error Girder support point K K0K0 λδλδ Z ΔK  1.2m Four Support Points used to minimize girder deformation Remaining deformation is nearly sinusoidal, the error period δ equals to the support length Deformation of 1.4429  2  m AlMg Alloy  6-7  m Result:  =1.2m  K/K=.0036  30  m   = 8.4° 10% Power Degr.

25. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 Parabolic Error Model I Periodic Function Periodic Modulation of Beam Profile. Leads to “Periodic” Damage Profile “Periodic” Damage Profile leads to… periodic Modulation of K

26. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 Parabolic Error Model II 10% Loss .2-.28rad or 11-16° Limits: 10% Loss  0.4- 0.7% loss of  K/K Damage Rate: 5x10 -4 /kGy 10% Level 0.4 / 0.7% 10% Dose 8 / 14 kGy Calculate Phase Shake and Power Loss

27. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 Lifetime Estimate for FLASH 2kGy/a Average Dose over Time 0.3kGy/a 1.2kGy/a Assumptions: Max.Tolerable  K/K (6nm, 10% Loss)  0.5% Resulting 10% Dose : 8 kGy Ave Dose. 2005-2007: 2.0 kGy/a,  40Gy/week Ave Dose. 2005-2008: 1.2 kGy/a  23Gy/week Future Dose: 0.3 kGy/a  6Gy/week Est. Lifetime [Years] 4 (pessimistic) 6,7 17.3 Future: 26.7

28. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 Summary Radiation induced Demagnetization observed at FLASH! With good will also visible at TTF1 in 2002 Damage rates range from 5 x 10 -4 / kGy FEL Simulation: Exercise for Li’s periodic Error Theory It is shown that this corresponds to 10% Power Loss levels of 8-14 kGy Life time is expected to be > 8 and < 26.7 years!

29. J. Pflüger / DESY - Radiation Damage Workshop Stanford June 19, 2008 The End