1. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Christophe S. Debonnel 1,2 S.J. Pemberton 1, R.P. Abbott 1, G.T. Fukuda 1 D.R. Welch 3, S.S. Yu 2, P.F. Peterson 1 (1) Thermal Hydraulics Laboratory Department of Nuclear Engineering University of California, Berkeley (2) Lawrence Berkeley National Laboratory Heavy-Ion Inertial Fusion Virtual National Laboratory (3) Mission Research Corporation, NM ARIES Meeting, San Diego, July 1, 2002 Towards a New Beam Line Point Design Fluid Dynamics in a HYLIFE Heavy-Ion Beam Line

2. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Outline Towards a new point design Fluid dynamics Vortex Gas Venting Magnetic shutter

3. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Larger numbers of beams can improve the performance of HIF drivers and targets Target gain increases with smaller spot size Using 100+ beams reduces individual beam current, improves focusing Current LBNL/LLNL/ UCB Point Design project is investigating 112 and 160 beam systems Cut-away schematic of an HIF thick-liquid pocket

4. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley A 9x9, 112-beam array has been designed Beam-line parameters: beam half angle: 15 mrad cylindrical jet standoff from beam cone to permit gravity deflection and pointing errors: 5-mm cylindrical jets have diameter of 90% of the liquid envelope diameter to allow for surface roughness Array parameters: 56 main pulse beams, 56 foot pulse beams spacing between beam array rows: 6° main pulse maximum beam angle: 24.7° minimum beam angle: 18.0 foot pulse maximum beam angle: 19.0° minimum beam angle: 8.5°

5. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley A 112-beam configuration (56 foot-pulse / 56 main pulse)

6. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley 9x9-beam Hybrid HYLIFE II configuration

7. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Cylindrical jet configuration for 9x9 array

8. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley 9x9 array showing beam tubes and magnets at 6 meters Detailed mechanical design of the beam tubes is needed to determine where steel, coolant, voids, and other materials will be located to allow injection/ extraction of vortex flow and optimize shielding

9. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley UCB has improved flibe vapor pressure predictions and identified a new salt composition allowing lower pressures Detailed activity coefficient data has allowed the vapor pressure of flibe to be accurately predicted at lower temperatures Ternary salt systems (“Flinabe,” LiF/NaF/BeF 2 ) have been identified with very low melting temperatures (320°C) Equilibrium vapor pressure (10 9 /cc at 400°C) Recent flibe vapor pressure prediction A degassing system may permit flinabe to be used for He/H 2 pumping

10. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Steaty-State Gas Pressure in Beam Tubes Low-temperature, low vapor-pressure flinabe is a very effective getter Assuming perfectly absorbing boundaries, density at last magnet (n f ) is given by Where n o = ambient density in chamber R o = chamber port radius L = distance from last magnet to chamber entrance For chamber at ~ 0.1 Pa, L=3m, vacuum in magnetic section can reach 10 -4 Pa range

11. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Strategies to Prevent Debris Deposition in the Beam Tubes Design efficient target chamber structures: Mass and energy fluxes at the entrance of beam ports should be as low as possible Venting in target chamber has been modeled to determine inlet boundary conditions for the beam tubes Liquid Vortex or Liquid Vortexes? Mechanical shutter too slow: Magnetic Sweeper

12. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Key heavy-ion thick-liquid chambers phenomena include gas dynamics and vapor condensation in the target chamber and in the beam tubes

13. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Cylindrical Jet Grids Beam access requires multiple round beam ports in the target chamber wall Cylindrical jet grids provide a square lattice of jet liquid

14. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Vortex Tubes Annular flow in the beam tubes can reduce the apertures in the square lattice to round ports called “Vortex Tubes” Stable centrifugal flow provides additional protection in the beam lines

15. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Vortex Layer Construction Formation of the vortex layer requires injection of liquid tangent to the inner pipe wall, directed at some angle  from the pipe axis An outer flow plenum and an inner wall with many small, properly aligned injection holes provides a good tube

16. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Vortex Tube Operation Vortex flow is redirected at either end of the vortex tube using suitable extraction sections The Berkeley tube uses a sudden extraction at the ‘target chamber’ end of the vortex tube, as shown in the figures (left) Extraction can also be accomplished with many small tubes (a reverse injection), which would maintain electrical continuity in the pipe wall

17. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Vortex Layer Flow Bi-directional injection 12 rows x 9 holes / 2 = 54 injection holes in each direction (N) Layer thickness depends only on the injection and pipe radii, not on the injection velocity! The Berkeley vortex’s ideal thickness T layer would be 1/6 the pipe radius Injection radius c of 1.2 mm and angle  of 45 deg

18. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Thickness Measurements The vortex tube was constructed using transparent PVC pipe. Masking on the outside of the pipe provided an easy way to measure the vortex layer thickness photographically. Actual thickness of the Berkeley vortex tube is 28% of the pipe radius Error ~2% of the pipe radius Standard deviation ~1% of the pipe radius 3 photographs of the vortex layer at various flow rates, and the empty pipe - darker bands are shadows indicating where the pipe is masked

19. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Annular Vortex Generation for IFE Beam Line Protection is Feasible Use of annular, centrifugally confined vortex tubes is reasonable for beam lines in thick-liquid IFE target chambers Ideal layer thickness estimates were insufficient to describe the experimentally observed thickness However, the actual thickness is within the desired range for IFE A more involved analysis from turbulent flow theory will be necessary for a more accurate prediction of layer behavior

20. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Cut-away view shows beam and target injection paths

21. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Axially symmetric 9x9 – Density Contour Plots

22. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Movie Time!

23. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Beam Tubes – TSUNAMI Density Contour Plots (I)

24. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Beam Tubes – TSUNAMI Density Contour Plots (II)

25. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Centerline Beam Tube: Density History

26. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Centerline Beam Tube: Axial Velocity History

27. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley LSP Plasma Diversion Simulation x-y Cartesian simulation. Box was 30-cm long and 10-cm wide. H + ions with a 10-100 eV temperature, 10 14 cm -3 density and a 3-9 cm/microsecond forward velocity. A no-field case and a case with electromagnetic fields and a 0.1 T B y field (for x > 15 cm). The B y case shows the plasma is stopped. Moving plasma blob confined by B B

28. The Heavy Ion Fusion Virtual National Laboratory UC Berkeley Conclusions Beam tube can be coated with liquid vortex. TSUNAMI predictions indicate that thick-liquid structures in target chamber should be supplemented by other engineering devices in the beam tubes to prevent debris contamination in the final-focus magnet region. 2D calculations predict expected plasmas diverted by a moderate strength magnetic field