1. Damage Levels V. Kain AB/Co
Contents …
Introduction
Assumed damage levels – TT40 accident
Controlled damage test
FLUKA results
Comparison with experiment
Conclusion
Scope …
Comparison of predicted damage limits with experiment
Damage limits for the LHC will not be defined
11/29/2018
Verena Kain, AB-CO

2. simulation vs. experiment!
Introduction
The damage limit of equipment is important input…
design of operational procedures
design of machine protection procedures
design of protection elements (robustness,…)
thresholds of monitoring systems (BLMs,…)
“safe” beam condition …
Knowledge on damage levels based on simulations…
especially for LHC energies and intensities
mostly static energy deposition calculated (FLUKA,…)
dynamic effects (shock waves,…)?
simulation vs. experiment?
simulation vs. experiment!
~25cm long hole in chamber
of QTRF in TT40. Both
Chamber and magnet had to
be exchanged.
10 cm
Inside, damage visible over ~1m (melted steel)
11/29/2018
Verena Kain, AB-CO

3. Assumed damage levels 450 GeV 7 TeV Damage limit at 450 GeV:
~ 2x1012 protons = 5% of full ultimate batch
7 TeV
~1010 protons
Damage limit at 450 GeV:
Check with reality: 1 full nominal batch > damage limit
25th of October: MSE trip during high intensity extraction. Damage of QTRF pipe and magnet.
~25cm long hole in chamber
10 cm
Inside, damage visible over ~1m (melted steel)
11/29/2018
Verena Kain, AB-CO

4. Reconstitution of Scenario and Comparison with Simulation
Analysis of post mortem data:
MSE tripped due to EMC of LHC beam 11ms before extraction
in 11ms field changes by 5%
number of extracted protons:
Reconstructed trajectory according to screen
shots.
Input for FLUKA simulation (x, x’).
The energy deposition result is very
sensitive to accurate input parameters.
The melting point of 314L: 1400°C.
Slit due to heat + stress, rather than
melting?
max. Temp. 1350°C
Meaningful comparison with
simulation:
CONTROLLED EXPERIMENT
stainless steel: 314L
11/29/2018
Verena Kain, AB-CO

5. Controlled Damage Test
Low-tech target, no extra instrumentation (no temperature sensors,…)
Simple target geometry:
Stack of high-Z metal plates
4 predefined beam intensities (A, B, C, D)
Intensities chosen to see certain effect on plate: melting/not melting
30 cm
108 plates
6 cm
Double Confinement
Screen
Motor
11/29/2018
Verena Kain, AB-CO

6. Target Description Every plate has unique longitudinal position:
Materials:
Zn, Cu, Stainless Steel (316L, INCONEL)
Special order of materials:
packages of 3 materials
Zn, Cu, 316L (INCONEL), Zn, Cu, 316L (INCONEL),…
plates 6cm x 6cm x 2mm
place-holders between plates (0.5mm) → avoiding molten plates sticking together
FLUKA model of target
Every plate has unique longitudinal position:
→ number on each plate
→ 3D experiment: longitudinal position + damaged area on plate
11/29/2018
Verena Kain, AB-CO

7. Melting starting in plate (nr.)
FLUKA
Results…
plate 11
plate 15 Cu
Heat of fusion
not taken into account…
Intensity
#bunches
Melting starting in plate (nr.) Zn Cu
316L
INCONEL A 12 - B 24 17 C 48 9 18 D 72 6 23
Results taking heat of
fusion into account…
¼ of a nominal batch
11/29/2018
Verena Kain, AB-CO

8. Damage test in TT40
Target was installed in TT40 in front of TED in air.
Target irradiation:
8th of November.
4 shots: intensities A, B, C, D
TED – TT40
Screen
Ti entrance window
Opened box: 5th of January → no full analysis yet
Took pictures of some plates (will take pictures of ALL plates)
11/29/2018
Verena Kain, AB-CO

9. Results … Observations when we opened the box…
outer confinement: no damage
first plates no damage as expected
after 6 packages more and more damage
no stress related damage, mostly very clean results…
11/29/2018
Verena Kain, AB-CO

10. Results… beam direction Only in this part shows melting … 11/29/2018
Verena Kain, AB-CO

11. Results… A B D C ☼ ☼ ☼ ☼ Plate 1, Zn Impact locations
for the different
intensities…
A B D C
☼ ☼ ☼ ☼
11/29/2018
Verena Kain, AB-CO

12. Results… Plate 7, Zn Marks of melting for intensity D…
Prediction: Nr. 6
11/29/2018
Verena Kain, AB-CO

13. Results… Plate 8, Zn Marks of melting for intensity D only…
Prediction for
intensity C: Nr. 9
11/29/2018
Verena Kain, AB-CO

14. Results… Plate 9, Zn Marks of melting for intensity D & C
Prediction: Nr. 9
11/29/2018
Verena Kain, AB-CO

15. Results… Plate 20, Zn Marks of melting for intensity D & C & B
11/29/2018
Verena Kain, AB-CO

16. Results… Plate 10, Cu Marks of heating for intensity D Prediction of
melting point: Nr. 11
11/29/2018
Verena Kain, AB-CO

17. Results… Plate 12, Cu Marks of melting for intensity D
Prediction: Nr. 12
11/29/2018
Verena Kain, AB-CO

18. Results… Plate 17, Cu Marks of melting for intensity D & C
Prediction: Nr. 18
11/29/2018
Verena Kain, AB-CO

19. Results… Plate 36, Cu Marks of melting for intensity D & C
Marks of heating
For intensity B
11/29/2018
Verena Kain, AB-CO

20. Results… None of the stainless steel plates shows holes.
INCONEL: as predicted
316L: predicted melting from plate 23
Needs further investigation…
11/29/2018
Verena Kain, AB-CO

21. Conclusions First examinations show good agreement with simulations
Zn, Cu, INCONEL as predicted
316L still unclear
Melting as predicted by FLUKA ± ~ 20%
uncertainties on beam size
Gives confidence that damage limits could be adequately simulated…
geometry has large effect
sensitive to details of beam impact
full modelling on case-by-case basis is essential
no simple scaling
11/29/2018
Verena Kain, AB-CO

22. Thanks to …
K. Vorderwinkler, J. Ramillon, F. Loprete, B.Goddard, J. Lettry, F. Decorvet, J. Vo Duy, R. Harrison, W. Wetterings, S. Sgobba, S. Calatroni, A. Dorsival, R. Schmidt, H. Vincke, M. Mueller, D. Forkel-Wirth, A. Desirelli
11/29/2018
Verena Kain, AB-CO