1. Federico Carra – EN-MME
Expected damage on TCTA collimator during HRMT09-LCOL experiment in HiRadMat facility Collimation Working Group F. Carra A. Bertarelli, A. Dallocchio, L. Lari, N. Mariani
Federico Carra – EN-MME

2. Federico Carra – EN-MME
Outlook
Scope of the study performed
FEA 3D model
Damage classification
Accident simulation results
Test 1
Test 2
Test 3
Conclusions
Federico Carra – EN-MME

3. Scope of the study presented
Three different tests on the TCTA will be performed in HiRadMat facility :
Test 1: to reproduce LHC asynchronous dump (single bunch setup, 1 bunch at 7 TeV energy impacting tungsten jaw)
Test 2: to assess the threshold damage on the collimator, in terms of beam energy and intensity (damage not imposing collimator replacement)
Test 3: to reproduce a destructive scenario and benchmark simulations (“Limits for Beam-Induced Damage: Reckless or too Cautious?“, A. Bertarelli et al. , Chamonix 2011)
How many SPS bunches (and at which intensity) are necessary to reproduce the 3 different scenarios, identified for the LHC?
FLUKA simulations – L. Lari: Equivalence of the energy peak +
Autodyn FEA – F. Carra: Equivalence of the damage produced on the jaw
Federico Carra – EN-MME

4. Equivalent damage: LHC vs. SPS
Preliminary analyses – FLUKA (L. Lari)
Equivalence of the energy peak
Equivalence of the maximum temperature (considering adiabatic conditions, constant specific heat)
Input for successive Autodyn FEA
Autodyn FEA
Equivalence of the damage produced on the jaw
Shockwave is propagating during the time between two successive bunches → pressure waves are not linearly superposing!
Federico Carra – EN-MME

5. FEA: 3D Model +/-10 mm through 5th axis Material EOS Strength model
Stiffener
(Glidcop modeled as OFE-Cu)
Water
Screw (x40)
(Stainless Steel)
Block Support
(OFE-Copper)
Cooling Pipes
(Cu(89%)-Ni(10%)-Fe(1%) modeled as OFE-Cu)
Jaw block (x5)
(W(95%)-Ni(3.5%)-Cu(1.5%) partly modelled as pure W)
Material
EOS
Strength model
Failure model
Tungsten
Tabular (SESAME)
Johnson-Cook
Plastic strain/ Hydro (Pmin)
Copper OFE
Polynomial
Stainless steel AISI 316
Shock
Plastic strain
Water -
Hydro (Pmin)
Federico Carra – EN-MME

6. Damage classification Level 1 : H ≤ 8 mm Level 2: H > 8 mm
Three different damage scenarios, with increasing severity, were identified:
Level 1 (Collimator need not be replaced). Limited jaw damage, an intact spare surface can be found relying on the 5th axis movement (+/- 10 mm). (Provided this movement is possible). Permanent jaw deformation is limited.
Level 2 (Collimator must be replaced). Damage to collimator jaw is incompatible with 5th axis travel (H > 8 mm). Other components may also be damaged (e.g. Screws).
Level 3 (Long down time of the LHC). Catastrophic damage to collimator leading to water leakage into beam vacuum (pipe crushing, tank water circuit drilling ...)
Jaw Damaged Area (red)
Level 1 : H ≤ 8 mm Level 2: H > 8 mm
Federico Carra – EN-MME

7. Test 1: beam parameters ??? LHC scenario SPS (HiRadMat) scenario 7 TeV
1 bunch
1,5E11 p/b
σ = 0.5x0.5 mm2
Impact parameter (test):
x = 2 mm
y = 10 mm
???
SPS (HiRadMat) scenario
440 GeV
X bunches
1,5E11 p/b
σ = 0.5x0.5 mm2
Impact parameter:
x = 2 mm
y = 10 mm
Bunch spacing: 50 ns
Preliminary estimation with FLUKA: 20 SPS bunches to have an equivalent energy peak
Energy peak in the axial coordinate, courtesy of L. Lari
Federico Carra – EN-MME

8. Test 1: expected damage provoked by 1 LHC bunch, 7 TeV
Tungsten damaged zone ~ 9 mm + plastic deformation of copper beam
Maximum pl. strain on pipes ~ 2.1%
Federico Carra – EN-MME
1 bunch, 7 TeV: cooling pipes

9. Test 1: equivalent SPS bunches
Pulse characteristics
Height of the damaged W surface [mm]
1 bunch, 7 TeV 9
16 bunches, 440 GeV
7.5
18 bunches, 440 GeV
8.4
20 bunches, 440 GeV
9.2
24 bunches, 440 GeV
10.5
30 bunches, 440 GeV
12.2
Pulse characteristics
Max. plastic deformation on cooling pipes
1 bunch, 7 TeV
2.10%
16 bunches, 440 GeV
1.07%
18 bunches, 440 GeV
1.26%
20 bunches, 440 GeV
1.40%
24 bunches, 440 GeV
1.70%
30 bunches, 440 GeV
2.08%
20 SPS bunches are necessary to provoke the same damage which is expected for 1 LHC bunch on the tungsten jaw
For an LHC equivalent damage on the cooling pipes, 30 SPS bunches are necessary!
Scratch on the W jaw vs. Damage on cooling pipes: which one to use as a reference?
Federico Carra – EN-MME

10. SPS (HiRadMat) scenario Inermet microstructure
Test 2: beam parameters
SPS (HiRadMat) scenario
440 GeV
X bunches → X = max. n. SPS bunches for which 80% of W melting temperature is not exceeded (S. Redaelli)
1,5E11 p/b
σ = 0.5x0.5 mm2
Impact parameter:
x = 2 mm
y = 10 mm
Bunch spacing: 50 ns
W grains
Metallic matrix
Inermet: Cu/Ni
Densimet: Fe/Ni
Inermet microstructure
Federico Carra – EN-MME

11. 6 bunches, 440 GeV – Temperature
Test 2: results
6 bunches to stay below 80% of W melting temperature (unavoidable melting of Cu/Ni phase)
No plastic strain of the tungsten active surface
Scenario equivalent to 1 LHC bunch, 7 TeV, 4.5e10 p
6 bunches, 440 GeV – Temperature
Federico Carra – EN-MME

12. Test 3: beam parameters ??? LHC scenario SPS (HiRadMat) scenario 5 TeV
4 bunches
1,3E11 p/b
σ = 0.5x0.5 mm2
Impact parameter (test):
x = 2 mm
y = 10 mm
Bunch spacing: 25 ns
???
SPS (HiRadMat) scenario
440 GeV
X bunches
1,5E11 p/b
σ = 0.5x0.5 mm2
Impact parameter:
x = 2 mm
y = 10 mm
Bunch spacing: 50 ns
Preliminary estimation with FLUKA: 50 SPS bunches to have an equivalent energy peak
Energy peak in the axial coordinate, courtesy of L. Lari
Federico Carra – EN-MME

13. Test 3: expected damage provoked by 4 LHC bunches, 5 TeV
Coarser mesh to reduce calculation times
Change of density between each of the last bunches is introducing an error > 10%
Calculation will be refined in the next weeks
Considerable vertical deformation of the copper beam
Extensive damage on the tungsten jaw
Plastic strain on cooling pipes ~ 10%!
4 bunches, 5 TeV: Vertical Displacement
Federico Carra – EN-MME

14. Test 3: equivalent SPS bunches
N. bunches
Height of the damaged W surface [mm]
4 bunches, 5 TeV
19.2
40 bunches, 440 GeV
12.8
50 bunches, 440 GeV
15.4
60 bunches, 440 GeV 18
80 bunches, 440 GeV 23
N. bunches
Max. plastic deformation on cooling pipes
4 bunches, 5 TeV
9.63%
40 bunches, 440 GeV
2.67%
50 bunches, 440 GeV
3.33%
60 bunches, 440 GeV
3.77%
80 bunches, 440 GeV
4.35%
~ 65 SPS bunches are necessary to provoke the same damage which is expected for 4 LHC bunch (5 TeV) on the tungsten jaw
In the HiRadMat facility, an equivalent damage provoked on the cooling pipes by 4 LHC bunches (5 TeV) is not reproducible! (decreasing beam σ would have very limited effect )
Federico Carra – EN-MME

15. Conclusions
Simulations were performed with FLUKA and Autodyn in order to evaluate the correct beam parameters for HRMT09 experience.
Test 1: 20 bunches proposed for an equivalent damage on W jaw; 30 bunches to have the same pipes plastic deformation. What part of the jaw to be taken as a reference?
Test 2: 6 bunches are proposed: Tmax < 0.8Tmelt(W), no plastic deformation of active jaw surface. Total beam intensity: 9e11 protons.
Test 3: 65 bunches are proposed: damage on W jaw is equivalent to the destructive case that should be reproduced. With current HiRadMat parameters, high plastic strain levels on cooling pipes cannot be reached.
TEST 1
N. bunches
Pulse Intensity
Damage extension on W jaw [mm]
Pl. Strain on cooling pipes
1 bunches, 7 TeV
1.5e11 p 9
2.10%
20 bunches, 440 GeV
3e12 p
9.2 
1.40% 
30 bunches, 440 GeV
4.5e12 p
10.5 
2.08% 
TEST 3
N. bunches
Pulse Intensity
Damage extension on the W jaw [mm]
Pl. Strain on cooling pipes
4 bunches, 5 TeV
5.2e11 p
19.2
9.63%
65 bunches, 440 GeV
9.75e12 p
~ 19 
~ 4%
Federico Carra – EN-MME