1. Feb. 9, 2002 Mucool FNAL LH2 Absorber R & D Mary Anne Cummings NIU Illinois Consortium for Accelerator Research (IIT, NIU, UC, UIUC), U Miss Oxford U

2. Feb. 9, 2002 Mucool FNAL Mucool LH2 Absorber Collaboration E. L. Black, M. Boghosian, K. Cassel D. M. Kaplan, W. Luebke, Y. Torun Illinois Institute of Technology S. Ishimoto, K. Yoshimura KEK M. A. Cummings, A. Dyshkant, D. Hedin, D. Kubik Northern Illinois University D. Errede, M. Haney University of Illinois, Urbana-Champaign M. Reep, D. Summers University of Mississippi Y. Kuno Osaka University G. Barr, W. Lau Oxford University C. Darve, C. Johnstone*, A. Klebaner, B. Norris, M. Popovic, S. Geer FNAL * also research faculty at IIT

3. Feb. 9, 2002 Mucool FNAL Cooling channel requires minimum “ heating ”  Low Z material  maximize radiation length  Minimize window thickness/Z while retaining structural integrity  Nonstandard window design Absorber Heat Management  Refrigeration: 100-250 W heat deposition from beam (~7W/cm)  Temperature and density stability: LH2 circulation, uniformity Mucool LH2 Absorber Issues Safety  Absorber: window strength, containment, relief valves, O2/LH2 separation, operation in dense, closed environment near “ ignition source ” (RF)  Cryo system: controls and feedback to maintain temperature Approx. eq. for emittance: Design/test drivers:

4. Feb. 9, 2002 Mucool FNAL The issue: A non-standard thin window design  No closed form expression for maximum stress vs. volume pressure  FEA (finite element analysis): geometry stress material strain volume pressure displacement Window tests } Procedure  Precision measurement of window  FEA predictions (New nonelastic and 3-d calculations! New results!)  Performance measurement 1. Strain gages out! 2. Photogrammetry : technique we wish to establish FNAL Safety Guidelines Established NEW!  FEA/Data agreement  ASME standards for room temperature and cryo burst tests

5. Feb. 9, 2002 Mucool FNAL Precision measurement of window and flange with CMM at FNAL Industrial Center. Absorber Window Design R rr Modified Torispherical integrated window and flange design (tapered detail at left). Machine parameters shown.

6. Feb. 9, 2002 Mucool FNAL Window manufacture (U of Miss) Backplane for window pressure tests Flange/window unit machined from aluminum piece

7. Feb. 9, 2002 Mucool FNAL Window Test Setup Test setup at NIU for window, front view: Backplane with connections, and with window attached Strain gages applied to window pressure control system

8. Feb. 9, 2002 Mucool FNAL Photogrammetry Non-contact measurement of strain by calculating displacement Compare with strain gage readout and FEA calculations FEA calc. for displacement

9. Feb. 9, 2002 Mucool FNAL Photogrammetry measurements during earlier pressure test. Note the projected dots!

10. Feb. 9, 2002 Mucool FNAL Latest window burst test

11. Feb. 9, 2002 Mucool FNAL Rupture tests Leaking appeared at 31 psi..outright rupture at 44 psi! 130  window 350  window Burst at ~ 120 psi The Latest: 340  window 1. 2. 3. Burst at ~ 120 psi Burst at > 120 psi

12. Feb. 9, 2002 Mucool FNAL NIU Photogrammetry results & non-linear FEA calculation Deformation of Window end-cap Vs test pressure 0 0.1 0.2 0.3 0.4 0.5 0.6 020406080100120140160 distance from end-cap centre line (mm) Test pressure (MPa) P=.18MPa FEA results by Oxford Comparison of results on 130  window 1 at 0.18 Mpa test pressure: FEA, non-elastic region included FEA, elastic region only

13. Feb. 9, 2002 Mucool FNAL Comparison of results on 130  window at 0.24 Mpa test pressure Comparing the Oxford and linear FEA results with the NIU photogrammetry data FEA, non-elastic region included

14. Feb. 9, 2002 Mucool FNAL 350 micron window (W. Lau) Non-elastic region included Three dimensional analysis, necessary for vibrational analysis FEA Calculations Stress distribution when first yield developed at 77.7psi (0.536 MPa) pressure

15. Feb. 9, 2002 Mucool FNAL Flow Tests Density maintenance: 1.Nozzle design and arrangement (E.Black, S. Dyshkant) Bates LH2 target heat carrying performance determined by total eN cross section measurements. We ’ ll need other confirmation. 2.3-dim LH2 absorber flow simulations (W. Lau) Will run 3-d sims for water, air, LH2 – demonstrate for water with the “ analog ” simulation at NIU 3.Absorber instrumentation Absorber integrated into a cryo system, with extreme temperature and pressure variations considered for safety. Heat loss/feedthrough

16. Feb. 9, 2002 Mucool FNAL Results of the fluid flow analysis:- Oblique nozzle arrangement with air flow at room temperature Inlet velocity = 100 m/s Velocity profile in Y-direction Air inlet

17. Feb. 9, 2002 Mucool FNAL Safety Mu-Cool Safety Panel has been formed. It consists of: Wes Smart (Chairman) Jim Kilmer Jim Priest Safety guidelines 1. Results of FEA calculations which show that the maximum window stress at 25 psid internal pressure is less than (0.25)x(ultimate strength). 2. Results of a cold pressure test per paragraph II.C.3.b.(i) (for metal flasks) of the LH2 Target Guidelines. I would suggest that at least one window be burst under cold conditions. Burst test at NIU with nitrogen 3. Results of a room temperature pressure test per paragraph II.C.3.b.(ii) of the LH2 Target Guidelines. Burst test 4. Copy of the Material Certification Sheet of the material from which the windows are fabricated provided 5. Other; including results of tensile testing samples of the material.

18. Feb. 9, 2002 Mucool FNAL Design of LINAC LH2 Absorber Beam Test

19. Feb. 9, 2002 Mucool FNAL Next  Burst test with nitrogen at NIU Feb ‘ 02  1 st safety report to committee Mar ‘ 02  Flow tests/ 3-d FEA study Apr ’ 02  Heat exchange/containment for LH2 cryostat May ‘ 02  Instrumentation Jun ’ 02 - ??  LH2 safety  LH2 monitoring  LH2 physics  11 cm radius absorber Jun ’ 02 -  Data acquisition  LH2  Beam  Cryotests for convection at NIU Jul ’ 02 - ?? The program gets redefined after every milestone!

20. Feb. 9, 2002 Mucool FNAL Thin Window Design Minimize window thickness: ANSYS Finite Element Analysis, Zhizing Tang, FNAL. beam axis displacement R r r Hemispherical: t = 0.5PL / (SE - 0.1P) s = 0.5D Ellipsoidal: t = 0.5PD / ( SE - 0.1P) s =.25D Torispherical: t = 0.885PD / ( SE - 0.1P) s =.169D t = min. thickness s = sagitta r s D r L R Minimum thickness depends on shape (ASME Standard) Variable thickness near window edges can further reduce the minimum window thickness near beam:

21. Feb. 9, 2002 Mucool FNAL Strain Gage Measurement Measure the strain on window with strain gages Use Finite Element Analysis program (ANSYS) to relate vessel pressure to maximum window strain – confirm this with strain gages applied to window surface FEA mesh for calcs. on the window-flange unit Instrumented window < two different gages

22. Feb. 9, 2002 Mucool FNAL Strain gage data 350m window Strain vs. time – the gage ceases to return to resting position after ~ 80 psi; demonstrating the yield point. Rosette Gage at 12 mm yielding..

23. Feb. 9, 2002 Mucool FNAL Forced-Flow Absorber Design Mucool ~ 100W (E. Black, IIT) Large and variable beam width => large scale turbulence Establish transverse turbulent flow with nozzles – complicated, hard to simulate External Heat Exchange:

24. Feb. 9, 2002 Mucool FNAL Internal heat exchange: Convection cell is driven by heater and particle beam. Heat exchange via helium tubes near absorber wall. Flow is intrinsically transverse. Convection absorber design Output from 2-dim Computational Fluid Dynamics (CFD) calcs. illustrate the concept. (K. Cassel, IIT) Lines indicate greatest flow near beam center. Studies are encouraging, but there is a poorly known parameter: h LH2, coefficient of convective heat transfer. Prototyping of this design is being done by Shigeru Ishimoto et al at KEK. <