Progress in Research on IFE Chambers and Targets

October 2003 – September 2004

Compiled by S. ReyesPlease direct comments and/or contributions to reyes20@llnl.gov

IFE Liquid Layer Protection – University of Wisconsin – MadisonP. Meekunnasombat, J. Oakley, M. Anderson, R. Bonazza

Publications and Presentations

Progress in IFE Technology: October 2003-September 2004

• One proposed idea to protect the first wall from fusion debris and to assist in the removal of thermal energy in an inertial fusion energy reactor is to use liquid sheets of molten salt.

• A shock tube is used to experimentally study a flat liquid layersubjected to a shock wave. The shock wave accelerates the liquid layer down the shock tube where it is imaged in the test section. The pressure history is recorded as well as images and volume fraction of the shocked water layer.

A water layer is placed on a 0.94 µm Mylar membrane at the interface section 0.46 m above the test section. A Mach 2.12 planar shock wave accelerates a 12.8 mm thick water layer downwards into the test section where the shocked liquid layer is imaged with a flash X-ray onto a conversion screen and recorded with a CCD camera as shown in theschematic below. In the figures on the right, X-ray images which have been converted to water volume fraction at different times after the shock acceleration are shown on the left and the average along the middle region are shown on the right. The shocked layer stretches significantly to about 18 times of its original thickness within about 3.3 ms and contains a maximum volume fraction of about 23%.

[1] Protection of IFE First Wall Surfaces from Impulsive Loading by Multiple Liquid Layers; P. Meekunnasombat, J. Oakley, M. Anderson and R. Bonazza, September 2004 [presented at the 16th Topical Meeting on the Technology of Fusion Energy, Madison WI].

[2] Experimental Study of A Shock Accelerated Water Layer with Imaging and Velocity Measurement; P. Meekunnasombat, J. Oakley, M. Anderson and R. Bonazza, Proceedings of the 24th International Symposium on Shock Waves, Paper 2692, Springer-Verlag, 2004.

Progress in IFE Technology: October 2003-September 2004 (Cont’d.)Thick-Liquid Protection — Georgia Institute of TechnologyS.G. Durbin, M. Yoda, S.I. Abdel-Khalik• Quantified influence of fine screens on initial conditions and surface ripple

fluctuations, see Figures 1 and 2– Uniform flow at nozzle exit for all flow conditioner configurations– Second screen decreases streamwise velocity fluctuations but not surface

ripple– Central disturbance observed in transverse velocity fluctuations and free-

surface fluctuations for conditioning with no screen• Quantified impact of boundary layer (BL) cutting on surface ripple and turbulent

breakup, see Figures 3 and 4– BL cutting improves surface smoothness and reduces turbulent breakup– Optimum configuration: Flow conditioning with one screen and 1% of total

mass flowrate cut from each face• Meets proposed target injection upper limit of N = 6 × 1021

• Surface ripple well below proposed HYLIFE-II limit of 0.07δ

Publications and Presentations[1] Durbin et al. (2005) Assessment and control of primary turbulent breakup of thick liquid sheets in

IFE reactor cavities—the ‘hydrodynamic source term’. To appear in Fusion Sci. Tech.[2] Durbin et al. (2004) Surface fluctuation analysis for turbulent liquid sheets. Fusion Sci. Tech. 45, 1[3] Durbin et al. (2004) The impact of boundary-layer cutting on free-surface behavior in turbulent liquid

sheets. 16th Technology of Fusion Energy Meeting, Madison, WI; submitted to Fusion Sci. Tech.[4] Durbin et al. (2004) Flow conditioning design in thick liquid protection. Ibid.[5] Abdel-Khalik and Yoda (2004) An overview of the fluid dynamics aspects of liquid protection

schemes for fusion reactors. Ibid. [Contributed paper]

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Figure 3. Impact of BL cutting on surface ripple at Re =120,000

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Progress in IFE Technology: October 2003-September 2004 (Cont’d.)REDOX Control in Molten Flibe (2 LiF:1 BeF2) – INEEL/ANL-WD. Petti, R. Anderl, M. Simpson, P. Sharpe, G. Smolik and Japanese collaborators on JUPITER-II: Task 1-1-A

• Experimental system has been developed to establish and control fluorine potentials in molten Flibe with controlled HF inputs.

• Analytical methods (QMS and an automated titration system) have been developed to measure HF concentrations in the outlet gas.

• REDOX control, i.e., HF removal, has been demonstrated by the insertion of Be metal sample in Flibe at 530ºC.

• Test series completed with variables: Be exposure time, HF concentration (~1000 & 2000 ppmv), and H2/HF ratio.

• Models have been developed to predict transients in HF concentration during and after Be metal insertion.

• Future goals are to study lower HF concentrations (10 ppmv) and establish Be solubility limit in molten Flibe.

Publications and Presentations[1] JUPITER-II Task 1-1-A Workshop, D. Petti, U. of Tokyo, September 17-18, 2004.[2] Two papers to be presented at ISFNT-7 (International Symposium on Fusion Nuclear Technology) May 22-27, 2005, in Tokyo,

Japan entitled, “Kinetic Studies of the Reaction of Hydrogen Fluoride with Beryllium in Molten Flibe” and “Interactions Between Molten Flibe and Metallic Be”.

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Figure 1. REDOX test system. Figure 2. Measurements of HF concentrationsin the outlet gas during and after Be insertion.

Figure 3. HF model predictions (black) and HF measured concentrations (pink)for Test 10 with 1000 ppmv HF input.

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Progress in IFE Technology: October 2003-September 2004 (Cont’d.)Thick-Liquid Protection, Chamber Dynamics, and Power Conversion—University of California at BerkeleyP.F. Peterson, C.S. Debonnel, G.T. Fukuda, P.M. Bardet, J. Freeman, and the thermal hydraulics team

Figure 1. Large vortex device (left) and established liquid vortex (right).

• UC Berkeley has designed and tested a new scaled large-vortex; the device proved to be a substantial improvement over last year’s vortex.

• A light mineral oil allowing molten salt scaled experiments with little distortion has been identified. Laser visualization of a scaled beam line vortex suggests that a 1-kHz surface renewal rate, which could allow accommodation of a 2-MW/m2 heat flux.

• The Vacuum Hydraulics Experiment is being upgraded for higher fidelity simulations of liquid jet disruptions.

• Flibe and flinabe vapor pressures are being measured at relevant temperatures. Preliminary results for pure BeF2 agree well with published values.

• The pre-conceptual design of a molten coolant gas cycle with 54% thermal efficiency and a compact turbine building has been completed.

Figure 2. Particle Image Velocimetrywill provide detailed velocity and

turbulence information.

Publications and presentations[1] P.M. Bardet, C.S. Debonnel, J. Freeman, G. Fukuda, B. Supiot, and P.F. Peterson, “Dynamics of liquid-protected chambers,”

submitted to Fusion Science and Technology.[2] P.M. Bardet, B. Supiot, P. Peterson, and O. Savas, “Liquid vortex shielding for fusion energy applications,” submitted to Fusion Science

and Technology.[3] H Zhao et al., “Optimized helium-Brayton power conversion for fusion energy systems,” submitted to Fusion Science and Technology.

Progress in IFE Technology: October 2003-September 2004 (Cont’d.)Thick-Liquid Protection, Gas Dynamics, and System Integration—Lawrence Berkeley National Laboratory and University of California at Berkeley C.S. Debonnel, S.S. Yu, P.F. Peterson, et al.

Figure 1. CDE schematic (left) and comparison between TSUNAMI prediction & CCD image (right).

• The Berkeley gas dynamics code TSUNAMI has been further validated throughLLNL’s Condensation Debris Experiment, which offers many similarities with IFE chambers. TSUNAMI predictions and experimental results agree well qualitatively and quantitatively (Fig.1).

• Effort toward a new heavy-ion point design is pursued and innovative target chambers are being explored. The RPD chamber was modified to accommodate the assisted-pinch beam propagation scheme; TSUNAMI was employed to model gas transport and control in the target chamber and the beam lines (Fig.2). The novel large vortex chamber is being investigated as well (Fig.3).

• The next version of TSUNAMI, “Visual Tsunami” is being developed.

Figure 2. TSUNAMI simulation of a thick-liquid chamber with assisted-pinch final

transport

Figure 3. Conceptual drawing of a large-vortex thick-liquid chamber.Publications and presentations

[1] C.S. Debonnel, S.S. Yu, and P.F. Peterson, “Progress towards thick-liquid fusion chambers for assisted-pinch and solenoid focusings,” Nuclear Instruments and Methods in Physics Research A, in press.

[2] C.S. Debonnel et al., “Visual Tsunami: A versatile, user-friendly, multidimensional ablation and gas-dynamics design code,” submitted to Fusion Science and Technology.

[3] C.S. Debonnel et al., “Validation of the TSUNAMI code through the Condensation Debris Experiment,” submitted to Fusion Science and Technology.

[4] S.S Yu et al., “The modular point design for heavy ion fusion,” submitted to Fusion Science and Technology.

Progress in IFE Technology: October 2003-September 2004 (Cont’d.)IFE Chamber Dynamics Modeling and Experiments— University of California, San Diego (http://aries.ucsd.edu/IFE)M. S. Tillack, F. Najmabadi, A. R. Raffray, S. S. Harilal, C. V. Bindhu, A. C. Gaeris, M. R. Zaghloul, J. O’Shay, K. Sequoia

• Research on EUV lithography began in our large new lab on February 2004 (Figure 1):- EUV spectroscopy added to our diagnostic capabilities (Jen-Optik transmission grating

spectrometer, energy monitor).- Modeling capabilities and personnel added for rad-hydro and atomic physics (Hyades,

Helios, Cretin, Hullac)• Experiments and modeling studies of underdense Sn and Ti, including CH (plastic foam) and

SiO2 (aerogel) carriers are currently underway (Figure 2).• Experimental improvements are under investigation:

- SBS cell for temporal pulse compression- density interferometry (Nomarski or Mach-Zehnder)- high-field electromagnets for magnetic diversion studies.

• New research on non-LTE plasmas and XUV emissions was started in September 2004 in collaboration with LLNL. The goal is a quantitative understanding of non-LTE plasmas:

- Address problems in which temperature cannot be uniquely related to the energy.- Address long-standing problems modeling radiation from low-density plasmas.

Figure 1. Larger lab with new EUV spectroscopy diagnostic capabilities

Figure 2. Experiments and modeling studies of underdense Sn using EUV spectroscopy

and new modeling capabilitiesFigure 3.Research on non LTE plasmas will include benchmarking of our modeling capabilities with well-characterized spectroscopic data

Progress in IFE Technology: October 2003-September 2004 (Cont’d.)Vapor dynamics and condensation studies – University of California, Los AngelesM. Abdou, A. Ying, N. Morley, P. Calderoni, M. Ni, T. Sketchley

• Super-heated flibe vapor cooling and condensation was measured experimentally in conditions scaled with HYLIFE-II parameters

• Pressure curves follow an exponential decay with time constant t = 6.58 ms with chamber walls at 500 C

• Although presence of residual H2 in the flibe pool (from HF purification) did not allow complete recovery of initial equilibrium conditions, the results suggest that for pure flibe vapor the total condensation period is below 60 ms - compatible with the desired 6 Hz rep rate of HYLIFE-II

A novel diagnostic for time-resolved spectroscopic lithium and beryllium vapors density measurements was developed and calibrated for lithium vapors. The vapor is excited in a controlled glow discharge in coaxial cylindrical geometry. Light emission is collected by a fiber optic lens and transferred to a compact spectrometer for analysis.A Langmuir probe is used to estimate emitting vapor temperature and density. Measured vapor parameters are correlated to emitted line intensity for real time characterization of condensation process.

SEM and EDX analysis of deposited flibe suggest that condensation is locally inhibited on surfaces oriented perpendicular to the vapor velocity in the initial expansion phase ( < 1 ms) that is characterized by high kinetic energy and a highly directional expansion. A possible explanation is that the center of those surfaces are flow stagnation points and the vapor temperature could locally remain above the critical temperature (Tc = 4500 K for flibe), therefore inhibiting the formation of a liquid phase. After the initial expansion phase the vapor has uniform vapor velocity and lower temperature resulting in the observed deposition of micron-sized droplets on all surfaces.

Measured

Reference

Publications and presentations:[1] P. Calderoni, A. Ying, T. Sketchley and M.A. Abdou “Vapor Condensation Study for HIF Liquid Chambers” presented at 15th HIF, June 2004 and accepted for publication on Nuclear Instruments and Methods in Physics Research -Section A [2] L. Schmitz, P. Calderoni, A.Ying, and M.A. Abdou “A Novel Diagnostic for Time-Resolved Spectroscopic Beryllium and Lithium Density Measurements” presented at 16th PSI, May 2004 and accepted for publication on Journal of Nuclear Materials [3] P. Calderoni “Experimental and numerical study of transient condensation of lithium and beryllium fluoride excited vapors for IFE systems” presented at IAEA RCM, 4-7 November 2003, IAEA Headquarters, Vienna [4] P. Calderoni, A. Ying., M. Abdou “Experimental and numerical study of transient condensation of lithium fluoride excited vapors for IFE systems”, presented at 20th SOFE, Oct 03 and to be published on Conference Proceedings

Progress in IFE Technology: October 2003-September 2004 (Cont’d.)Integration, Systems Studies, Safety & Environment and Driver-Chamber Interface — Lawrence Livermore National LaboratoryR. P. Abbott, J. F. Latkowski, W. R. Meier, S. Reyes and R. C. Schmitt

“Dry wall” HYLIFE-II:7.4 appm He/dpa

HYLIFE-II w/ 60 cm Flibe:5.4 appm He/dpa

• Completed neutronics analyses for various liquid breeder options for use in Heavy-Ion Fusion chambers. Results show reduction of the DPA rate compared to dry-wall chambers, which allows accelerated damage testing with currently available fission-based neutron sources (see Figure 1).

• Performed activation analyses for various candidate steels for the HYLIFE-II chamber. Waste options assessment shows ODS ferritic steel as the most promising structural material option for the HYLIFE-II concept, given its low activation performance and potential for high temperature operation.

• Cross-section uncertainty analysis applied to HYLIFE-II chamber material. It has been found that only the effect of Nb and W induces a significant uncertainty in the overall low-activation performance of these steels.

• Completed system analysis of modular solenoid option for heavy ion driver and contributed to analyses of thick-liquid vortex chamber that could be used with solenoid-based driver.

• Performed safety assessment of Be use in IFE from chemical and radiological toxicity perspectives. Segregation of inventories and additional confinement are essential to minimize potential beryllium exposures.

Figure 1. Use of thick liquids reduces DPA rate increasing opportunities for IFE material testing in currently available fission-based neutron sources

Publications and Presentations

[1] S. Reyes, L. C. Cadwallader, J. F. Latkowski, J. Gomez Del Rio, J. Sanz, “Safety Issues of Beryllium Use in IFE Power Plants,” 20th IEEE/NPSS Symposium on Fusion Engineering (SOFE), October 14 - 17, 2003, San Diego, CA.

[2] S. Reyes, “Latest Developments on IFE Materials Response to X-Rays and Safety Studies at LLNL,” Joint GA/UCSD Seminar November 19, 2003.[3] S. Reyes, “The Path to Economic Fusion Energy”, Seminar at Monterey Institute of International Studies (MIIS) December 8, 2003.[4] J. F. Latkowski, S. Reyes, “Neutronics on heavy Ion Fusion Chambers,” 15th International Symposium on Heavy Ion Inertial Fusion, Plasma Physics Laboratory,

Princeton University, NJ, June 2004.[5] W.R. Meier and B.G. Logan, "Systems Analysis for Modular Versus Multi-Beam HIF Drivers,“ 15th International Symposium on Heavy Ion Inertial Fusion, Plasma

Physics Laboratory, Princeton University, NJ, June 2004.[6] D. A. Petti, S. Reyes, L. C. Cadwallader, J. F. Latkowski, “Status of Safety and Environmental Activities in the US Fusion Program,” 16th Topical Meeting on the

Technology of Fusion Energy (TOFE) Madison, Wisconsin, September 2004.[7] W. R. Meier, “ Update on Progress and Challenges in the Development of Heavy Ion Fusion,” 16th Topical Meeting on the Technology of Fusion Energy (TOFE)

Madison, Wisconsin, September 2004.[8] J. F. Latkowski et al., “Pulsed X-Ray Exposures and Modeling for Tungsten as an IFE First Wall Material,” 16th Topical Meeting on the Technology of Fusion

Energy (TOFE) Madison, Wisconsin, September 2004.[9] J. Sanz, O. Cabellos, S. Reyes, J. F. Latkowski, “Effect of activation cross-section uncertainties in selecting steels for the HYLIFE-II chamber to successful waste

management,” 23rd Symposium on Fusion Technology (SOFT), Venice, Italy, September 2004.