1. Felix Dietrich | AWLC14 | 14.05.2014 | Stress simulation in the ILC positron target with ANSYS Felix Dietrich (TH-Wildau), Sabine Riemann, Friedrich Staufenbiel (DESY)

2. Felix Dietrich | AWLC14 | 14.05.2014 | page 2 Outline > Alternative source > Goal of the studies > Model > Implementation into ANSYS > Temperature calculation > Results > Summary > Next steps

3. Felix Dietrich | AWLC14 | 14.05.2014 | page 3 Alternative source

4. Felix Dietrich | AWLC14 | 14.05.2014 | page 4 Goal of the studies > Beam parameters are given (  ~29J/g peak energy deposition @SLC) > How is the dynamic stress evolving in the target with 300Hz scheme in the tungsten target > Target lifetime depend on static and dynamic stress Energy deposition within fraction of a nanosecond  instantaneous temperature rise Reaction of material within milliseconds  Stress dynamics > Benchmark: SLC target  But SLC number of positrons per second was about 50 times lower than at ILC

5. Felix Dietrich | AWLC14 | 14.05.2014 | page 5 Model

6. Felix Dietrich | AWLC14 | 14.05.2014 | page 6 Implementation into ANSYS

7. Felix Dietrich | AWLC14 | 14.05.2014 | page 7 Temperature calculation > With good mesh, the temperature change resulting from energy deposition by each bunch shows regular behavior with negligible numerical errors

8. Felix Dietrich | AWLC14 | 14.05.2014 | page 8 Temperature rise: 1st attempt > The temperature increases per bunch by 1.6K > The graph shows the temperature rise for the first triplet

9. Felix Dietrich | AWLC14 | 14.05.2014 | page 9 Results: Stress evolution – Model 2 > The Picture shows the equivalent stress (von- Mises) at diferent positions in the Material > The Picture was taken at: 1.0205 µs  (t=5ns  first bunch of mini train) > Deformation is scaled by 730 for visualization; max. surface displacement is about 8µm

10. Felix Dietrich | AWLC14 | 14.05.2014 | page 10 Result: Short time – Model 2 > Results are calculated for 1µs > Red line shows max. stress at any given point at one time > The other lines are calculated an the center of the disc at different depth (1.4cm equals the surface; 0.9cm equals a depth of 0.5cm)

11. Felix Dietrich | AWLC14 | 14.05.2014 | page 11 Result: Conclusion short time > Max. temperature rise by one triplet is T=210°C within ~1  s > Heat dispersion into the target body within microseconds is negligible  temperature of the target body is 22°C > Max. stress after one triplet 377MPa > Every mini train adds a different stress load  First mini train +225MPa  Second mini train +110MPa  Third mini train +37MPa > Max. stress by one triplet is below fatigue stress limit 377MPa<520MPa

12. Felix Dietrich | AWLC14 | 14.05.2014 | page 12 Results: Long time > First attempt  2 µs pause > Same configuration like the first graph > Results are preliminary

13. Felix Dietrich | AWLC14 | 14.05.2014 | page 13 Temperature rise: 2nd attempt > The temperature rises linearly over the whole mini train > That saves computing time

14. Felix Dietrich | AWLC14 | 14.05.2014 | page 14 Results for 2nd attemept: Model 1 > Results are calculated for 3µs > Max. stress is about 400MPa > Results are preliminary

15. Felix Dietrich | AWLC14 | 14.05.2014 | page 15 Results for 2nd attempt: Model 2 > Results are calculated for 3µs > Max. sress is about 420MPa > Results are preliminary

16. Felix Dietrich | AWLC14 | 14.05.2014 | page 16 Summary

17. Felix Dietrich | AWLC14 | 14.05.2014 | page 17 Next steps > Simulations of a longer period:  Few triplets  Include target rotation  Check whether interferences of stress waves are possible > Degradation of material is expected due to irradiation  evaluation of dynamic load has to be repeated with modified parameters

18. Felix Dietrich | AWLC14 | 14.05.2014 | page 18 Addition

19. Felix Dietrich | AWLC14 | 14.05.2014 | page 19 Addition

20. Felix Dietrich | AWLC14 | 14.05.2014 | page 20 Addition