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Dump Core: MD test and energy deposition STUDIES (FLUKA simulations)

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  1. Jose A. Briz EN-STI-FDA On behalf of: François-Xavier Nuiry, Giulia Romagnoli, Jaakko Johannes Esala, Edouard GrenierBoley, Jose Briz Monago, Marco Calviani, Vasilis Vlachoudis, Tobias Polzin, YannickCoutron, Didier Steyaert And all the involved people in EN-STI, EN-MME, EN-HE, TE-VSC, TE-MSC, BE-OP, BE-BI, BE-RF, HSE-RP PS Internal Dump Review Meeting – 04/10/2017 Dump Core: MD test and energy deposition STUDIES (FLUKA simulations) PS Dump Review Meeting

  2. Outline PS Dump Review Meeting • Beam dumping mode in PS ring: Direct Impact vs. Beam Shaving • Multi-turn Approach in FLUKA • Machine Development Test: Validation of FLUKA Multi-turn Approach • Energy Deposition Studies on Dump Core • Radiation Damage on Materials of Dump Core • Summary and Conclusions

  3. Beam Profiles Horizontal profiles EDMS Doc. N. 1612293 Vertical profiles Current Future* Intensity ~2.75 times higher and even smaller beam size * Main beam type to be used after LHC Injectors Upgrade (LIU) PS Dump Review Meeting

  4. Direct Impact vs. Beam Shaving Beam Shaving Direct Impact Beam vertical profile Cu OFE Beam vertical profile HL-LHC beam 26 GeV/c 2.3e13 ppp σh=1.74 mm σv=0.87 mm Peak energy densities are 2 orders of magnitude higher!!! PS Dump Review Meeting

  5. Beam Dumping Process in PS Ring Future Current PS Dump Review Meeting Dumping process last ~3-7 ms LIU beams much more demanding than current beam types

  6. Multi-turn Approach M1 M2 PS ring Dump B A PS Dump Review Meeting Transversal coordinates of beam particles along the PS ring change due to beam optics of the machine: beta-tronic motion Mathematically, the transformation of coordinates is described using some machine parameters:twiss parameters(α, β,γ), machine tune and dispersive terms The One Turn Matrix (OTM) describes that transformation after a full passage along the ring

  7. Multi-turn Approach M1 PS ring B A M2 Dump Horizontal: 1 meter drift of dump section (no magnetic field) Dispersion matrix One turn matrix Transformation of coordinates from B to A for turn number n: PS Dump Review Meeting

  8. Multi-turn Approach B A M1 M1: 1 meter drift of dump section (no magnetic field) PS ring Vertical: Horizontal: M2 Dump No dispersion considered in vertical plane Transformation of coordinates from B to A for turn number n: PS Dump Review Meeting

  9. Multi-turn approach: Simulations Hypotheses M1 PS ring M2 Fixed Dump Variable: depending of the beam. Determines impact position of every proton turn after turn WhereQi are horizontal and vertical tunes of themachine Worst case (among realistic values) has been considered in our simulations: Qy=6.33 Qx=6.23 PS Dump Review Meeting

  10. Multi-turn approach: Simulation Hypotheses 1 meter-long drift region (no magnetic field) Beam particles tracking starts at A. Dump starting position is vertically 3 cm down wrt beam center. When theyarrive to B, they are transported back to A using machine matrices (OTM and 1m-drift matrix) Primaries are returned to FLUKA only when a crossing with the dump is possible (x10 faster tracking) Secondary particles and backscattered or strongly deflected primaries are lost in the machine so they are not tracked back from B to A In our simulations Dump is static and particles are spatially shifted at A and accordingly shifted back at B 1 m drift A Dump Future B SS47 Maps of energy density are recorded in 150 µs steps  ~20-60 maps to cover full beam dumping (up to 9 ms) Current PS Dump Review Meeting

  11. Machine Development Test (MD1198)Validation of FLUKA multi-turn approach Performed on 27/07/2017 PS Dump Review Meeting

  12. Machine Development - MD1198 PS Dump Review Meeting • An experimental test of the current dump was performed on 27/07/2017 “MD1998: PS dump measurements for future design” • Three beam types were dumped: • Beam profileswere recorded using wire scanners • Beam intensity losseswere measured by using a tomoscope (WCM) • Experimental results are compared to simulations using the Multiturn approach in FLUKA

  13. Beam Losses during a Beam Pulse Dumping X X Downstream sections show losses PS Internal Dump acts more as a beam diluter than a beam absorber PS Dump Review Meeting

  14. Beam Profile and Intensity for LHC25 72b beam PS Dump Review Meeting

  15. Beam Profile and Intensity for TOF beam PS Dump Review Meeting

  16. Conclusions from MD Tests PS Dump Review Meeting • Comparison of experimental and simulated results shows nice overall agreement • More statistics on beam loss curves desirable to deeper understand small discrepancies found • Validation of the multi-turnshaving approach for internal beam dumping in PS ring • Implemented code in FLUKA for multi-turn shaving approach reflects similar results to experimental observations • FLUKA results are starting point for all our design studies of dump core

  17. Energy Deposition Studies on Dump Core PS Dump Review Meeting

  18. Dump Geometry in FLUKA Graphite 1 cm 12 cm 11 cm BEAM CuCrZr Cooling pipes 4 cm 23 cm 13.2 cm BEAM PS Dump Review Meeting

  19. Approximation of Curved Shape in FLUKA 0.5° 1.5° 1.4 mm 3° R=570 mm Approximation is due to scoring reasons in FLUKA PS Dump Review Meeting

  20. Study of Energy Deposited in Dump Core • Spatial distribution of energy deposited studied using meshes of: • Horizontal: 0.5 mm width • Vertical: 5 µm thickness • Longitudinal: 0.2/0.4 mm length Most impacted region BEAM Mesh4 Mesh2 Mesh3 Mesh1 1 cm 2 cm 1 cm 1° tilt angle PS Dump Review Meeting

  21. Spatial Meshes used in FLUKA BEAM BEAM Coarse mesh for full energy map of energy density in the core Fine meshes for accurate peak energy density determination PS Dump Review Meeting

  22. Energy Density Distribution from FLUKA HL-LHC Values shown are accumulated per pulse BEAM CuCrZr HL-LHC beam p=26 GeV/c 2.4e13 ppp σxxσy=1.74 mm x 0.87 mm εx=1.8 mm mrad εy=1.8 mm mrad Graphite CuCrZr BEAM PS Dump Review Meeting

  23. Depth of Energy Deposition Peak energy densities at 1 mm depth are more than 2 orders of magnitude lower than at the surface: 1800 vs. 10 J/cm3/150 µs 1800 J/cm3/150 µs 0-5 µm 145-150 µm 10 J/cm3/150 µs 1-2 mm 40 µm High energy densities but very superficial PS Dump Review Meeting

  24. Results on Peak Energy Density Selecting this time bin (most critical for HL-LHC) Future Current Peak is pessimistic case due to the approximation of rounded shape by tilted planes PS Dump Review Meeting Energy density maps every 150 µs ~20-60 energy density maps

  25. Temperature Increase in Water 0.3 K/pulse as max. adiabatic temperature rise in water No problematic Pipe 1 2 3 9 12 PS Dump Review Meeting

  26. Energy Absorbed in the Dump PS Dump Review Meeting Dump as a beam diluter more than a beam absorber Studies of Radiation Damage in Downstream Equipment and Radiation Protection aspects are required

  27. Radiation Damage on Materials of Dump Core PS Dump Review Meeting

  28. Structural Damage on Dump Core Lower general damage than current dump (~1 order of magnitude) Lower peak DPA on copper region than current dump (~2 orders of magnitude) Graphite protects the copper block from structural damage 0.5 DPA/year 0.03 DPA/year in Graphite 0.02 DPA/year 0.002 DPA/year in CuCrZr Damage threshold energies considered: Eth(Graphite) = 30 eV - typical value 30-35 eV Eth(CuCrZr and SS304L) = 40 eV CuCrZr Graphite POT=2.4e17 (assumed same POT for current and future dumps) PS Dump Review Meeting

  29. Irradiation on Graphite • 0.03 DPA/year estimated in Graphite block of PS dump • Experience at CERN: CNGS air cooled graphite target (SPS beam) • About 1200°C reached for each pulse • At the end of operation: 1.5 DPA • No problem observed on graphite • 3.5 x 1013 protons per pulse, • 10.5 µs pulse length < 1 mm spot size • 2 extractions per cycle separated by 50 ms, occurring every 6 s •  2 000 000 extractions achieved by end of 2009 •  4.5 x 1019 protons at 400 GeV/c on CNGS target per year Graphite rods 2020PT (Mersen) [Ref]: Spallation materials R&D for CERN’s fixed target program, M. Calviani et al. IWSMT, Oct. 2014, Austria PS dump graphite irradiation shall not be a concern PS Dump Review Meeting

  30. Irradiation on CuCrZr [3] Plastic region • Peak value obtained of 0.002 DPA per year (0.04 DPA in 20 years) in CuCrZr block of PS Dump • Localized peak DPA • Information for neutron irradiationfound in literature • CuCrZr shows radiation hardening until saturation values around 0.1 – 0.5 DPA [1][3]  Some hardening may occur • CuCrZr is void swelling resistant [1][2](below 2% density change for up to 150 DPA [1]) • Some thermal conductivity degradationmay occur (5 – 10 % reduction for doses> 0.1 DPA at < 150 °C [2]) Elastic region [2] [1] [1] C. Bobeldijk (ed.). (1994). Atomic and Plasma-Material Interaction Data for Fusion. Vol. 5. Supplement to the Journal Nuclear Fusion [2] S.A. Fabritsiev & S.J. Zinkle & B.N. Singh. (1996). Evaluation of copper alloys for fusion reactor divertor and first wall components. Journal of Nuclear Materials. Vol. 233-237. pp. 127-137. [3] M. Li & M.A. Sokolov & S.J. Zinkle. (2009). Tensile and fracture toughness properties of neutron-irradiated CuCrZr. Journal of Nuclear Materials. Vol. 393. pp. 36-46. PS Dump Review Meeting

  31. Summary and Conclusions PS Dump Review Meeting • Beams after LIU-PS are more demanding than current ones: x2.75 higher intensity and even smaller spot size • Experimental MD testhelps to validateourapproach in thesimulations • HL-LHC beam type produces the highest energy density in the dump for single impact • Beam Dump acts as a beam diluter (~90% of incoming energy is not absorbed by the dump) • Damage on Dump Core is lower than current dump and specially in the Copper region due to the inclusion of Graphite diluter. No remarkable macroscopic effects expected on Dump Core based on data from other projects at CERN and from literature

  32. Thanks for your attention

  33. Extra slides

  34. Beam dumping mode in PS Beam dumping in PS consists of beam shaving instead of direct impact PS Dump Review Meeting • Beam dumping normally takes place whenbeam is circulating in the ring • PS ring revolution time of beam particles at extraction energies (p=26 GeV/c, Etotal=26.017 GeV): =0.99935 • Average dump speed: 0.8 m/s • Dump moving vertically 1.68 μm per PS revolutiontime (turn) vs. ~mm sigma of beam  dumping takes few milliseconds

  35. Radiation Damage on Dump Core ~105MGy/year Graphite CuCrZr ~500 MGy/year PS Dump Review Meeting

  36. Gas production On-going analysis *Averaged values along full volume PS Dump Review Meeting

  37. Current PS Internal dumps Dump block X X Dumping movement PS Dump Review Meeting 2 dumps installed in SS47 and SS48 since 1975 Copper block: 13.2x3.6x13 cm3, ~6 kg Usually required for beam dumping at extraction energies

  38. Current dump for future beams Tservice for Cu OFE • FUTURE BEAM • LHC 25ns HL • 2.3 1013 protons • @ 26 GeV/c • σhxσv: 1.74x0.87 mm2 • CURRENT BEAM • LHC 25ns 2015 • 0.87 1013 protons • @ 26 GeV/c • σhxσv: 1.85x0.98 mm2 A new design is needed Plot and thermal analysis performed by J. Esala and G. Romagnoli (EN-STI-TCD) PS Dump Review Meeting Simulations to check the performance of current dumps with future beams:

  39. Dumping process Vertical profiles Particlesdumped vs. time Dumping process vs. Time similar to shavingbeam vertical profiles PS Dump Review Meeting

  40. Interaction of protons with matter Energy Loss p+ Direct beam particle loss Ionization and Coulomb scattering interactions can cause, eventually, the loss of primary protons if they lose enough energy/momentum Machine cannot hold circulating protons below a certain momentum (machine acceptance) PS Dump Review Meeting • Ionization losses (with atomic electrons of dump material) • Coulomb scattering (with atomic nuclei of the dump) • Nuclear reactions

  41. Losses of primary protons PS Dump Review Meeting Beam particles can be lost due to: • Controlled losses: proton “absorbed” in the dump  Nuclear reactions but not the full cascade of secondaries generated!! • Uncontrolled losses: Acceptance Losses along the PS ring • Machine acceptance: Δp/p=5/1000=0.5% (approx. value provided by BE department) • Primary protons with are considered lost in the machine

  42. Multi-turn approach in FLUKA For every primary proton arriving at the border of our geometry we know: [x, x’, y, y’, p] = 26 GeV/c BEAM DUMP ACCEPTANCE CHECK (0.5%): 1 m VACUUM lost in the machine! no yes Continue tracking PS Dump Review Meeting

  43. Multiturn approach in FLUKA M1 1 m drift Dump A B M2 PS ring SS47 Qi horizontal and vertical tunes of the machine OneTurn Matrices: OTMx and OTMy Horizontal: machine parameters Dispersive correction for terms higher than linear Vertical: PS Dump Review Meeting

  44. Multiturn approach in FLUKA M1 1 m drift Dump B A M2 PS ring SS47 PS Dump Review Meeting

  45. Answer to Question: Machine Tunes Qx=6.33 Qy=6.25 X’=dx/ds Y’=dy/ds BEAM BEAM X Y Qx, Qy are the betatron wavenumbers or tunes of the machine: can be seen as the number of oscillations that the beam ellipse in the corresponding phase space, (X,X’) or (Y,Y’), rotates per beam revolution along the machine For Qy=6.25 the ellipse rotates 6 times and a quarter every turn in the accelerator. So every 4 turns particles imping at same vertical position. Every 2 turns we absorb the top side of the beam profile we see in the animation PS Dump Review Meeting Snapshots every 4 turns!!

  46. Beam Dumping in the PS ring Cross-check of multi-turn approach in the simulations Experimental values taken with: Wall Current Monitor measure in SS3 the beam intensity each turn PS Dump Review Meeting

  47. Parametric Studies for Dump Geometry PS Dump Review Meeting

  48. Dump speed 5 m/s 1.2 m/s 0.8 m/s The faster the higher temperature rise (at our reachable velocities regime) PS Dump Review Meeting Different dump moving speeds have been tested: 0.8, 1.2 and 5 m/s Plot and thermal analysis performed by J. Esala and G. Romagnoli (EN-STI-TCD)

  49. Dump materials Service temperatures indicated with dashed lines Lighter materials cause larger losses in the machine Graphite seems to be the only one below the material service temperature Lighter materials worse for machine protection PS Dump Review Meeting Plot and thermal analysis performed by J. Esala and G. Romagnoli (EN-STI-TCD)