LIEBE: Design of a molten metal target based on a Pb-Bi loop at CERN-ISOLDE T. De Melo Mendonca, M. Delonca, D. Houngbo, C. Maglioni, L. Popescu, P. Schuurmans, T. Stora (May 21, 2014) 03/01/2020 5th High Power Targetry Workshop 1 Outline Introduction/context Proposed design Diffusion simulations

Numerical results Heat Exchanger (HEX) Beam impact Conclusion & next steps 03/01/2020 5th High Power Targetry Workshop 2 Introduction/context 03/01/2020 5th High Power Targetry Workshop 3 Introduction/context (1)

Aim of LIEBE target: validation of conceptual design for the EURISOL direct target by developing a prototype for CERN-ISOLDE. Some keywords: high power target, short-lived isotopes, Collaboration started in May 2012 for the LIEBE (Liquid Eutectic Lead Bismuth Loop Target) project: WP definition WP holder Coordinator WP1 : Coordination CERN T. Stora WP2 : Conceptual Design and simulations SCK-CEN P. Schuurmans WP3 : Construction, assembly CERN M. Delonca WP4 : Instrumentation CERN T. Mendonca WP5 : Safety and Licensing CEA A. Marchix

WP6 : Target characterization and analysis PSI D. Schumann WP7 : Radiochemistry SINP S. Lahiri WP8 : Offline commissioning IPUL K. Kravalis WP9 : Online operation CERN T. Mendonca 03/01/2020 5th High Power Targetry Workshop 4 Introduction/context (2) ISOLDE: on-line isotope mass separator @ CERN Proton beam from PSB: 1.4 GeV 2 A

3e13 protons/pulse Cycle: 1.2 s 3 kW average power Instantaneous power: 1 GW 03/01/2020 5th High Power Targetry Workshop 5 Introduction/context (3) 03/01/2020 5th High Power Targetry Workshop 6 Proposed design 03/01/2020 5th High Power Targetry Workshop 7

Proposed design (1) Proposed by EURISOL 03/01/2020 5th High Power Targetry Workshop 8 Current front end + target Proposed design (2) Main loop Pump/motor Current target unit Diameter: 300 mm 03/01/2020

5th High Power Targetry Workshop 9 Proposed design - main part (3) Filling tank Container * 650 mm Beam Diffusion chamber Pump pipes HEX + heating/isolating elements all along the loop * D. Houngbo, SCK-CEN 03/01/2020

5th High Power Targetry Workshop 10 Proposed design HEX (4) HEX LBE Casserole in between water and LBE LBE circulation Water block 03/01/2020 5th High Power Targetry Workshop 11 Proposed design HEX (5) 5 working temperatures defined in step of 100 C

5 inlets on each side 1 outlet on each side For each working temperature defined, only two inlets are used. 400 C 600 C 500 C 200 C 300 C 03/01/2020 5th High Power Targetry Workshop 12 Diffusion simulations 03/01/2020 5th High Power Targetry Workshop

13 Diffusion simulations (1) Diffusion: model from Fujioka et al. (NIM 186 (1981) 409) With Static units Courtesy T. Mendonca, CERN 03/01/2020 Diffusion optimized for droplets shape Need a grid on the container to create the shower Holes diameter: 0.1 mm, Thickness plate: 0.5 mm Material: SS304L 5th High Power Targetry Workshop

10 mm 14 Diffusion simulations (2) Hg (T1/2= 130 ms) as reference: 177 Diffusion Improvement of diffusion with temperature Increasing droplet radius will decrease the released fraction Diffusion efficiency of 38% for 100 ms, 44% for 200 ms in the diffusion chamber Maximum operating temperature limited by vapor pressure of LBE Courtesy T. Mendonca, CERN

03/01/2020 5th High Power Targetry Workshop 15 Diffusion simulations (3) Conclusions Diffusion efficiency is improved with: Droplet shape Temperature Falling time of the droplets (lower outlet velocity, longer falling distance) 03/01/2020 5th High Power Targetry Workshop

16 Numerical results 03/01/2020 5th High Power Targetry Workshop 17 Numerical results HEX (1) Need to keep the target at the desired working temperature for temperature ranging from 200 C till 600 C Power contributions: + - Beam Pump Pump

Radiation - HEX Beam 330 to 990 W Pump 2 200 W Pump power extraction Radiation power extraction 03/01/2020 5th High Power Targetry Workshop 18 Numerical results HEX (2)

Assessment of HEX behavior with CFX Dimensioning of an HEX: Water LBE Flow rate (l/s) 0.22 0.23 T inlet (C) 27 Variable T outlet (C) < 90 Variable

03/01/2020 Problem: The HEX must extract less power @ 600 C than @ 200 C BUT power extracted depend on the surface of exchange, the average heat exchange coefficient and the temperature of both fluids involved -> need of a variable HEX! 5th High Power Targetry Workshop 19 Numerical results HEX (3) Example @ 600 C Tmax water = 79 C Summary of results: T max water (C) P extracted (W)

200 C 78 3 180 300 C 83 3 050 400 C 73 2 890 500 C 68 2 820 600 C

79 2 650 Tmax LBE = 597 C 03/01/2020 5th High Power Targetry Workshop 20 Numerical results HEX (4) Conclusions Temperature and power extraction are in the proper range (values have been checked over the full range of temperature, from 200 C up to 600 C) Further analysis must be computed considering bad thermal contact between

the different parts Prototype will validate the design Temperature controlled with heating elements installed all along the loop 03/01/2020 5th High Power Targetry Workshop 21 Numerical results Beam impact (1) Assessment of beam impact with Fluka & Ansys Autodyn Geometry considered Isolde beam parameters Container: Stainless Steel 304, solid part,

Lagrangian part Liquid: LBE, SPH elements Use of 40 gauges along beam axis 03/01/2020 5th High Power Targetry Workshop 22 Numerical results Beam impact (2) Material definition Standard variables @ 600 C. , Cp, k Shock EOS (Linear model) Gruneisen model

Us = shock velocity, = Gruneisen coefficient, = particle velocity, C0 and S = fitting parameters Failure mechanism Hydrodynamic tensile limit 2 values considered: -150 kPa and -1.9 GPa (no value available for LBE) Courtesy E. Noah, Un Geneva 03/01/2020 5th High Power Targetry Workshop 23 Numerical results Beam impact (3) Analysis for 50 s (1 pulse = 32.6 s) under hydrodynamic tensile limit

Shock waves deposit energy onto the weakest point of the container (grid part). Stresses up to 350 MPa (Yield = 390 MPa) in less than 1 ms. 03/01/2020 5th High Power Targetry Workshop 24 Numerical results Beam impact (4) Analysis for 50 s (1 pulse = 32.6 s) over hydrodynamic tensile limit Deformation scale: *9 Cavitation in the liquid will induce splashing of the LBE and projection of droplets with very high velocity in the diffusion chamber. 03/01/2020 5th High Power Targetry Workshop 25

Numerical results Beam impact (5) Conclusions & Outlook The geometry needs an improvement to avoid resonant shock waves Impact of beam onto the container should be further investigated: Negligible impact expected Need more detailed simulation to prove it Simulation must be computed for longer time 03/01/2020 5th High Power Targetry Workshop

26 Conclusion & next steps 03/01/2020 5th High Power Targetry Workshop 27 Conclusion & next steps Preliminary optimization design Test of the Heat Exchanger foreseen Optimization of the irradiation container under beam impact on-going

Off-line tests scheduled in the near future 03/01/2020 is available, under 5th High Power Targetry Workshop 28 Thank you for your attention! 03/01/2020 5th High Power Targetry Workshop 29 Thanks to all the contributors

V. Barozier A. P. Bernardes K. Kravalis F. Loprete S. Marzari R. Nikoluskins F. Pasdeloup A. Polato H. Znaidi (and many others) 03/01/2020 5th High Power Targetry Workshop 30

Back up slides 03/01/2020 5th High Power Targetry Workshop 31 Introduction/context (4) Specificity of RIBs (Radioactive Ion Beam) production via the ISOL (Isotope separation on-line) technique: Isolde target unit Diffusion Effusion Target Transfer line Extraction electrode Ion source

Plasma Extracted ion beam Leaks Primary beam Condensation Isotope production Leaks Release loss Decay loss 03/01/2020 Decay loss Leaks Condensation Decay loss Neutrals Sidebands Multiply charged

5th High Power Targetry Workshop 32 Introduction/context (5) Specificity of RIBs (Radioactive Ion Beam) production via the ISOL (Isotope separation on-line) technique: Isolde target unit Radioactive ion beam (RIB) intensity: Transfer line Heated: decrease adsorption in effusion process Cooled: trap condensable isobaric contaminants RIB intensity [s-1 A-1] Target density [atom cm-2]

Diffusion+effusion efficiency I RIB prod N t arg et I prim beam diff eff ion Cross section [cm2] Target Heating Diffusion improves with temperature 03/01/2020 Proton beam intensity [s-1 A-1] 5th High Power Targetry Workshop Ionization efficiency 33 Diffusion/effusion simulations (3)

Effusion: Monte Carlo The effusion efficiency is dependent on the geometry of the container/diffusion chamber, the sticking time, the mean free path and number of collisions with droplets and surface of containment. Sticking times of ~10-12 s negligible effect in efficiency Effusion release efficiencies between 22% and 34% for residence times in the diffusion chamber between 100-200 ms Estimated release efficiencies (diff+eff) of ~ 8% for 100 ms and ~ 15% for 200 ms.

Thanks to T. Mendonca 03/01/2020 5th High Power Targetry Workshop 34 Concept 5 - Results 1 kg of LBE in Feeder Volume, 2 feeder grids of 2520 apertures 1-mm or 0.5-mm thick feeder grids 2520 evacuation apertures 1.5-m/s inlet velocity ~0.2-bar pressure drop Stable uniform flow between 500 K 1500 K Static-Pressures (Pa) Velocity Vectors (m/s) Feeder Volume Irradiation Volume

Houngbo D.- LIEBE project, Computational Fluid Dynamics (CFD) analysis.- Workshop on Radioactive Ion Beam Production and High-Power Target Stations.- Mol, Belgium, 16-18 September 2013.- [Presentation] Numerical results HEX (3) Example @ 600 C Tmax water = 79 C Velocity in water and LBE Tmax LBE = 597 C Pressure in water for case LBE @ 200 C 03/01/2020 5th High Power Targetry Workshop 36 Summary of results: T max water (C)

200 C 78 300 C 83 400 C 73 500 C 68 600 C 79

P extracted Power extracted (W) Numerical results HEX (4) 3610 3110 200 (W) 3 180 CC a s300 eC 2610 1400 3 050

C 500 C 600 C 2110 2 890 2 820 1610 200 250 300 350 400 450 500

550 600 Temperature LBE (Deg C) 2 650 03/01/2020 5th High Power Targetry Workshop 37