Mercury Beam Dump Simulations

1. Mercury Beam Dump Simulations Tristan Davenne Ottone Caretta STFC Rutherford Appleton Laboratory, UK November-2008

2. Mercury beam dump design from NUFACT Feasibility Study

3. Mercury beam dump design from NUFACT Feasibility Study

4. Thermal shocks and magnetohydrodynamics in highpower mercury jet targetsJ Lettry, A Fabich, S Gilardoni, M Benedikt, MFarhat and E Robert

5. Agitation ‘eruption’ of mercury pool surface due to 24GeV proton beam Fluka Simulation - Energy deposition in mercury pool How much of the beam energy is absorbed in the beam dump?

6. Agitation ‘eruption’ of mercury pool surface due to 24GeV proton beamAutodyne simulationSplash following pulse of 20Terra protons

7. Agitation ‘eruption’ of mercury pool surface due to 24GeV proton beamAutodyne simulationDamage to underside of 15mm stainless steel plate (maybe need sprung baffles!)

8. Damage as a result of high speed impact of a mercury dropletStainless Steel vs. Ti-6Al-4V

9. Consider helium bubbles in beam dump to reduce splash velocity Proton beam helium

10. Mercury beam dump design from NUFACT Feasibility Study

11. Agitation of mercury pool surface due to impinging mercury jet 2 phase CFX model mercury jet velocity = 20m/s Angle of attack = 5.7° mercury pool surface area = 0.05m2

12. Summary Conclusions Simulations indicate that mercury splashes with a maximum velocity of 75m/s will result when a pulse from the undisrupted 24GeV beam is absorbed by the mercury beam dump. Mercury splash velocity of 30m/s has been observed experimentally when a 1GeV proton beam interacted with a trough of mercury. Lettry et al. A 3mm diameter mercury droplet impacting a stainless steel plate at 75m/s are predicted to cause significant damage. Ti-6Al-4V is predicted to be more resistant to damage due to higher ultimate strength and shear strength. Significant agitation of the mercury surface also results from the impingement of the mercury jet. Questions 1. How many pulses from the beam must the beam dump be able to survive? 2. Are sprung baffles a useful approach to containing a mercury splash from the beam dump? 3. Would helium bubbles be a useful addition to the beam dump in order to move the energy deposition deeper in to the mercury pool?

13. Tungsten Powder Jet Update Ottone Caretta STFC Rutherford Appleton Laboratory, UK November-2008

14. High speed videos: some of the tests propelled by air ~3 bar 2cm Thank you to EIP at RAL for providing the video equipment used for these experiments

15. =3/10bar =~atm water supply 24 29 9 Rig Flow Diagram 38 44 40 To the pneumatics 6 11 16 14 27 25 17 20-21 8 10 22 26 30 2 39 28 3 5 23 31-32-33 4 1 37 36

16. Powder Jet Rig 31st Oct 2008

17. Powder Jet Rig 31st oct 2008

18. Schedule November 10-18 system and control wiring November 19-27 system control development November 27-28 system commissioning November 27-christmas preliminary experiments

19. Helmholtz Capture Solenoid Update Peter Loveridge P.Loveridge@rl.ac.uk STFC Rutherford Appleton Laboratory, UK November-2008

20. Overview Purpose To investigate the feasibility of a proposed capture solenoid with an axial (“Helmholtz”) gap Method Development of Study-2 design… Split both the 1st SC coil and the NC insert coil in two Downstream coils remain unchanged Introduce current grading in the SC “Helmholtz” coils Investigate a potential mechanical design with lateral target entry/exit slots Start with min slot size 20 mm x 200 mm, -an optimistic case! Conceptual layout of the Helmholtz capture solenoid

21. On-axis Field Profile Magnetic field plot (Tesla) On-axis field profile • SC contribution • ~12 Tesla, flat plateau in target region • NC contribution • ~7 Tesla, unwanted trough in target region • Total • Close approximation to the study-2 field with the exception of the trough in the target region

22. Inter-Coil Forces Magnetic force plot from an early Helmholtz geometry iteration • Axial Forces • Cumulative axial compressive force ~ 16,000 metric tonnes! • Axial Forces balanced between first 6 SC coils • Must house all these coils in a single cryostat to avoid transferring loads up to room temperature • Huge attractive axial forces must be transferred across the Helmholtz gap • Requires careful mechanical design • Radial forces • Equivalent to an internal pressure of ~1500 bar! In coils SC01and SC02 • Leads to large hoop-stresses as seen in study-2 design • Strength of NC insert coil is a particular concern

23. Summary Status Have developed a (very) conceptual design for a capture solenoid with lateral target entry/exit slots (200 mm x 20 mm) Includes a basic level of realism: “Reasonable” current densities in SC and NC coils 1st guess at space envelopes for cryostat, coil support-structure, shielding Issues Effect of field trough on pion capture (John Back) How to cope with the huge inter-coil forces Large tensile hoop stresses in coils How to integrate with a solid target system Comments: The combination of very high field and large bore required by the capture solenoid constitutes a formidable engineering challenge We should keep an open mind about what kind of magnet geometry would best suit a solid target system.