New TCSPM Design Outcome of HRMT-23: Robustness of HL-LHC jaws

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Presentation transcript:

New TCSPM Design Outcome of HRMT-23: Robustness of HL-LHC jaws F. Carra*, A. Bertarelli, L. Gentini, J. Guardia, M. Guinchard, L. Mettler, E. Skordis Special ColUSM: Material and design readiness for LS2 productions 02/05/2017 *With many contributions from colleagues of EN/MME, EN/STI, BE/ABP, EN/HE, HSE/RP, SMB/SC, EN/EA

Outline TCSPM design scenarios HRMT-23 recap LHC and HL-LHC materials: simulations and benchmarking Conclusions 02/05/2017 F. Carra

TCSPM design scenarios TCSPM: low-impedance secondary collimator, jaw in MoGr Design cases  Same as LHC TCS (CFC): Slow losses Nominal operation: 1h BLT Accidental case: 0.2h BLT (10s) Direct beam impact (incident) Asynchronous beam dump: 8 full LHC bunches impact Beam injection error: 288 SPS bunches impact Note that FLUKA simulations for the asynchronous beam dump case on HL-LHC materials are not available. For a CFC secondary, this has always been less critical than BJE  Check from FLUKA For a tertiary, we are using equivalent SPS bunches to assess the asynchronous beam dump error  Check from FLUKA at 7 TeV For a tertiary: 1 LHC bunch 02/05/2017 F. Carra

Direct beam impact incidents HRMT-23 Goal: determine consequences of failure scenarios affecting machine performance for LHC Run 2, Run 3 and HL-LHC Failure Scenario Beam Type Beam Energy [TeV] Intensity Deposit. [p+] Beam Emittance [m] RMS beam size [mm] Injection Error LHC Ultimate 0.45 4.9e13 3.5 1 Run 2 BCMS 3.7e13 1.3 0.61 HL-LHC 6.6e13 2.1 0.77 Injection Error (BIJ) LIU BCMS 5.8e13 Asynchronous Beam Dump BCMS Run 2 7 1.3e11 ~0.5 Asynchronous Beam Dump (ABD) 2.3e11 ~0.6 Demonstrate the viability of a low-impedance collimator solution Address the issue of TCT robustness limit Demonstrate the robustness of present carbon-based collimators (TCS, TCP) against injection failures with smaller emittances 02/05/2017 F. Carra

HRMT-23 experiment recap Three separate complete jaws TCSPM MoGr jaw with MoGr tapering TCSPM CuCD jaw with MoGr tapering TCSP CFC jaw with Glidcop tapering Extensive instrumentation 126 strain gauges (4 MHz) 42 temperature probes (200 Hz) 60 optical fiber Bragg gratings (500 Hz) LDV, water pressure sensor, high speed / HD camera, ultrasound probes, etc. Stainless steel vacuum vessel (p > 10-3 mbar) Be/CFC vacuum windows Horizontal actuation stroke (H) 35 mm Vertical actuation of tank stroke (V) +/-140 mm 02/05/2017 F. Carra

HRMT-23 experiment beam parameters Test Runs: 24-31 July 2015 Beam energy: 440 GeV Bunch spacing: 25 ns Protons/bunch: up to 1.32e11 1 to 288 bunches per pulse Beam size (): 0.35 to 1 mm Different impact positions Total Pulses: 100 (excluding alignment) Total Bunches: 8110 (excluding alignment) Total Protons: ~ 1e15 Equivalence SPS/LHC in terms of damage for Asy. Dump (Inermet)  24 bunches HL-LHC  48 bunches HL-LHC injection error on MoGr: 5413 J/cm3 HRMT-23 max energy on MoGr: 5659 J/cm3 (+5%) HL-LHC injection error on CFC: 2443 J/cm3 HRMT-23 max energy on CFC: 3158 J/cm3 (+29%) 12 April 2016 Linus Mettler - HL-LHC Collimator Tests at CERN

MoGr and CFC experimental results MoGr on HL-LHC jaw survived the impact of several 288 b pulses with  down to 0.35 mm (peak energy density 5% higher than HL-LHC injection error) CFC on LHC jaw survived the same impacts Suggests that MoGr qualifies as an alternative to CFC in terms of robustness with a factor 5 to 10 gain in electrical conductivity A hole in the TCSP Glidcop tapering was observed, while the two TCSPM jaw taperings, in MoGr, are visually unscathed  MoGr is a more robust option as a tapering material also for TCSP MoGr after multiple impacts MoGr tapering intact CFC after multiple impacts Damaged Glidcop tapering Glidcop melting (red) 02/05/2017 F. Carra

CuCD experimental results CuCD on HL-LHC jaw survived (with a limited surface scratch on the Cu coating) the impact of 24 b,  0.35 mm at 440 GeV, roughly equivalent to 1 LHC bunch at 7 TeV At 48 b (~2 LHC 7 TeV bunches) the scratch is more severe, but the jaw appears globally undeformed, roughly equivalent to 1 HL-LHC bunch at 7 TeV This would qualify CuCD as an superior material for TCT jaws (presently in Tungsten alloy). Local damage induced by Asynchronous Beam Dump could be compensated by jaw shift with 5th axis Both MoGr taperings ok, no trace of high temperature on the BPM buttons CuCD surface damage 24 b, σ 0.35 mm, impact 0.5 σ MoGr tapering intact 144 b, σ 0.61 mm, impact 3.05mm 48 b, σ 0.35 mm, impact 0.5 σ 02/05/2017 F. Carra

HRMT-23 Post-irradiation – November 2016 HRMT-23 stored at b. 954, sealed, until November 2016 When the dose rate reached acceptable values (80 mSv/h at contact with the downstream flange), RP gave the go-ahead for the dismounting Closed bunker needed: impossible to exclude a prior the risk of contamination. Dismounting done at b. 867-R-P58. Performed by S. Favre (EN-MME-MA) with support from E. Berthomé. K. Weiss and C. Saury from RP Collective dose for the intervention: ~10 mSv. No contamination measured. Jaws inserted into plastic bags and CR code applied on all, then registered in TREC Then placed on a pallet, also registered in TREC as the container of the three items (HCPWPAB001-CR000002) Tank closed, everything re-transported to b. 954 Many thanks to the colleagues involved in these operations! (EN/MME, EN/STI, EN/HE, HSE/RP, SMB/SC, EN/EA, BE/ABP, …) 02/05/2017 F. Carra

HRMT-23 Post-irradiation – April 2017 The disassembling of the tank, for the recuperation of the table and other delicate components (connectors, switch box, glasses, LVDTs, motors, ...) to be re-used in Multimat was cone in April 2017 at b. 109. All the unrecovered equipment (Be windows, tank, pump) is treated as RP waste. Testing program of the three jaws (first non-destructive, then destructive) launched – G.Gobbi working on this. At this stage, preliminary conclusions given at the LMC in August 2015 (failure of Glidcop tapering, survival of MoGr tapering, survival of MoGr and CuCD absorbers to the respective failure scenarios) are confirmed 02/05/2017 F. Carra

Simulations Simulations with linear elastic models HL-LHC intensity beam injection error simulated For CuCD, asynchronous beam dump equivalent to 1 LHC bunch, same case as Inermet180 Simulation parameters CFC and MoGr: 288 bunches 6.4∙1013 total protons (HL-LHC) 440 GeV 7.2 µs impact duration Beam sigma 1 mm Emax,CFC ~ 60% LIU-BCMS; Emax,MoGr ~ 80% LIU-BCMS Impact depth 5 mm Elastic Constants CFC MoGr CuCD Ex [GPa] 2.8 7.1 160.5 Ey [GPa] 57.5 74.0 Ez [GPa] 93.0 Gxy [GPa] 3.5 4.3 75.1 Gxz [GPa] 6.4 Gyz [GPa] 10.6 31.3 nxy 0.11 0.13 0.07 nxz 0.10 nyz 0.19 Simulation parameters CuCD: 24 bunches 3.1∙1012 total protons (eq. 1 LHC bunch damage) 440 GeV 1.95 µs impact duration Beam sigma 0.61 mm Impact depth 3.05 mm 02/05/2017 F. Carra

Normal strains on CFC jaw CFC simulation: BIJ Reference values: M. Borg, Numerical Modelling and Experimental Testing of Novel Materials for LHC Collimators, master thesis Factor of 2 in resistance between Y and Z  orthtropic With this model, mostly critical is the high tensile strain in Y direction Reference System Normal strains on CFC jaw Maximum over time Simulation [microstrain] Reference value Ultimate strain ex 2000 2600 ey 1400 850 ez 740 1800 ey on CFC ey>1000 microstrain 02/05/2017 F. Carra

Normal strains on MoGr jaw MoGr simulation: BIJ Reference values: M. Borg, Numerical Modelling and Experimental Testing of Novel Materials for LHC Collimators, master thesis Higher strains than CFC jaw, but similar ratio against reference ultimate strain Again, Y is the most critical direction Reference System Normal strains on MoGr jaw Maximum over time Simulation [microstrain] Reference value* Ultimate strain ex 4500 5200 ey 6500 2000 ez 1800 ey on MoGr 02/05/2017 F. Carra

CuCD simulation: ABD Here the assessment of material failure is fairly easy: for impacts close to the surface, mechanism controlled by material melting HRMT14 outcome: at these energy levels, the beam sigma contribution is very weak, what matters is the energy integral. Damage recoverable by 5th axis 24 b, σ 0.35 mm, impact 0.17mm 144 b, σ 0.61 mm, impact 3.05mm Significant difference between CuCD and Inermet. For estimating the precise factor of robustness gain, we would need to compare two identical scenarios in terms of sigma, impact depth and intensity. Rough estimation: 10- 15 48 b, σ 0.35 mm, impact 0.17 mm 02/05/2017 F. Carra

Comparison numerical model / experimental measurements Simulations Conservative. Why? CFC, graphite and MoGr are not linear in σ/ε. Energy dissipation related to internal friction  should be simulated as viscoelastic materials Comparison numerical model / experimental measurements Graphite dynamic test 𝐺 𝑡 = 𝐺 ∞ + 𝐺 0 𝑒 − 𝑡 𝜏 Model built for R4550 graphite1, ongoing for MoGr (more complex: transverse isotropy) CuCD plasticity CuCD: also non linear, because of plasticity of the matrix + also internal friction! (see next slide). 1L. Peroni, M. Scapin, F. Carra and N. Mariani (2013). Investigation of dynamic fracture behavior of graphite. In B. Basu, Damage assessment of structures X, Trans Tech Publications Inc, pp. 103-110. 02/05/2017 F. Carra

CuCD simulation: at intensity ~1 LHC bunch HRMT shot #124: CuCD 24 bunches, s 0.61 mm, impact 5s Pseudo-plasticity of the material taken into account! EM disturbance wave propagation noise simulation CuCD block5 vertical strain back face 45.8 kHz 64.1 kHz Numerical overestimation of the results when applying a linear elastic model is evident. Plastic+ viscoelastic model needed for CuCD! 63.4 kHz 45.0 kHz Why observed decrease in amplitude with time? Damping 31 January 2017 Federico Carra

MoGr simulation: lower intensity HRMT shot #200: MoGr 24 bunches, s 0.6 mm, impact 5s Orthotropic elasticity simulated up to now, must evolve into orthotropic viscoelasticity wave propagation noise simulation Dynamic tests at Polito for the construction of the strength model  launched 02/05/2017 F. Carra

When failure fails to predict failure... Let’s have a look at the key ingredients of a simulation: Equation of state ✔ Strength model – Failure model x Threshold 2 TCT: limit for spallation Numerical failure does not mean functional failure Example: CuCD failing locally (melted), but overall the structural resistance of the material is guaranteed  damage can be recovered with 5th axis Fragmentation, spallation acceptable if the extent is limited and recoverable But ANSYS does not distinguish between numerical and functional failure! If we want to explore the acceptable damage, more sophisticated methods required  Autodyn SPH mesh, as we did for Inermet180 02/05/2017 F. Carra

Conclusions Jaws tested in HRMT-23 performed well (MoGr surviving energy density of HL-LHC injection error and CuCD surviving asynchronous beam dump) TCSP Glidcop tapering melted, all TCSPM taperings in MoGr remained intact Non destructive tests ongoing and destructive testing on irradiated blocks foreseen → to examine damage, amount of plasticity, loss of thermophysical properties due to Cu / CD debonding, etc. What if the beam σ was higher than expected in the HRMT23 shots? (Almost) irrelevant for CuCD  high energetic impact with melting, damage depends more on the integral of energy in the impacted volume than on the energy peak. Also, CuCD was tested up to intensities 6 times higher than the nominal scenario Relevant for the onset of damage for MoGr and CFC, but: Several high-intensity shots on the jaws  statistics Hard to believe that the functional damage on the jaw can be more relevant than what we had on CuCD, with melting involved… The same scenarios will be tested again in Multimat, with new BTV/BPKG system, as well as solutions such as coating, monitoring and actuation system, FCC materials, … 02/05/2017 F. Carra

Conclusions Simulations with elastic material models are over-conservative, since they ignore plasticity, damping, and other nonlinear phenomena observed in laboratory tests As a consequence, the local failure predicted for CFC and MoGr even with larger σ than HL- LHC scenarios were not observed in HRMT-23 Nonlinear models required, to be built with dynamic tests: Inermet180, Molybdenum, R4550 graphite: completed with Politecnico di Torino MoGr: launched at Politecnico di Torino CuCD and CFC: to be launched Complemented by high-temperature measurements at MME MechLab  new machine equipped for that If one wants to examine the fragmentation process  SPH method with Autodyn needed Fracture modelling becomes more and more important transitioning towards future high intensity accelerators (not only HL-LHC, but also FCC) FLUKA Asynchronous beam dump simulations on CuCD, MoGr, CFC needed. Simplified case is sufficient (bunches impacting in the same spot) to compare CuCD robustness with that of Inermet180 and to verify that the scenario is less relevant than beam injection error on MoGr and CFC 02/05/2017 F. Carra

Thanks for your attention

Backup slides

CFC simulation: temperature Maximum temperature reached on the CFC jaw: 685 ˚C Maximum temperature in the instrumented points ~170 ˚C Temperature at the impact Beam 02/05/2017 F. Carra

CFC simulation: shockwaves The frequency of the shockwaves to be acquired ranges from 3 kHz (longitudinal) to 45 kHz (transversal); maximum strains to be acquired ~3000 microstrain Jaw flexural oscillation has a frequency of ~80 Hz and a maximum amplitude of ~1 mm Transverse velocity of the external surface ~5 m/s 300 ms Reference System 02/05/2017 F. Carra

CFC simulation: Glidcop support The compressive stress provoked by the impact on the Glidcop plate exceeds the material yield strength Equivalent plastic strain is ~0.17% This compressive state remains once the jaw comes back to room temperature  permanent deflection induced ~50 mm Jaw permanent deflection Beam 02/05/2017 F. Carra

MoGr simulation: temperature Maximum temperature on MoGr ~1200˚C, much lower than melting point (~2590˚C) The temperature peak of 1290˚C is found on the Aluminium tapering  local melting Another calculation performed with Glidcop tapering still shows T>Tmelt  alternative solution to be found (proposal: MoGr tapering) On the strain gauge closer to the beam impact, T~360˚C > Tlim OK if this occurs only at the very last shot: the strain gauge will register the dynamic phenomenon before being detached by the incoming thermal wave This model uses aluminium tapering and ultimate strain from different grade Tmax<Tmelt,MoGR Al tapering melting Temp (˚C) 02/05/2017 F. Carra

MoGr simulation: shockwaves Maximum temperature on MoGr ~1200˚C, much lower than melting point (~2590˚C) The frequency of the shockwaves ranges from 2.5 kHz (longitudinal) to 50 kHz (transversal); maximum strains around 5000 microstrain Jaw flexural oscillation frequency of ~125 Hz and a maximum amplitude of ~2.1 mm Transverse velocity of the external surface ~12 m/s 20 ms This model uses aluminium tapering and ultimate strain from different grade Reference System 02/05/2017 F. Carra