reported by: m. s. tillack with contributions from: f. najmabadi uc san diego w. r. meier lawrence...

reported by: M. S. Tillack with contributions from: F. Najmabadi UC San Diego W. R. Meier Lawrence Livermore National Lab S. Abdel-Khalik Georgia Institute of Technology A. R. Raffray UC San Diego C. L. Olson Sandia National Lab Status of IFE Chamber Research and Power Plant Studies 1st meeting of the FESAC subcommittee on IFE Oct. 27-28, 2003

Overview 1. Power plant studies Historical background Recent studies: ARIES-IFE, HI RPD, ZFE Future plans 2. Chamber research programs Dry walls and chambers Thin liquid wall protection Thick liquid wall chambers Program status and needs

Part I: Power plant studies

Power plant studies: from SOLASE to the present pre-1990 2000 and beyond: ARIES-IFE, RDP 1990-91 1990s post-2000: ARIES-IFE RPD ZFE DPSSL HYLIFE-II

Modern power plant studies provide self-consistency, innovations, and assessments to guide R&D Utility Input Mission and Goals Evaluation Based on Customer Attributes Attractiveness Characterization of Critical Issues Feasibility Design Options Assessment Present Data Base and Designs Redesign R &D Needs Development Plan

Objectives: Analyze & assess integrated and self-consistent IFE chamber concepts Understand trade-offs and identify design windows for promising concepts. The research was not aimed at developing a point design. Approach: Six classes of realistic target were identified. Advanced target designs from NRL (laser-driven direct drive) and LLNL (Heavy-ion-driven indirect-drive) were used as references. To make progress, the activity was divided based on 3 chamber classes: Dry wall chambers; Solid wall chambers protected with a sacrificial zone (such as liquid films); Thick liquid walls. These classes of chambers were researched in series with the entire team focusing on each. ARIES integrated IFE chamber analysis and assessment research was a 3-year exploration study, recently completed

ARIES-IFE Design windows were developed for direct-drive dry-wall chambers Thermal design window Detailed target emissions Transport in the chamber including time-of-flight spreading Transient thermal analysis of chamber wall No gas is necessary Laser propagation design window(?) Experiments on NIKE Target injection design window Heating of target by radiation and friction Constraints: Limited rise in temperature Acceptable stresses in DT ice

Two methods for establishment of thin-liquid walls were studied in ARIES: wetted film and forced film ( more details in the R&D section ) Liquid Injection First Wall Detachment Distance x d X-rays and Ions ~ 5 m Can a stable liquid film be established and re- established over the entire surface of the reactor cavity (including penetrations)? Can a minimum film thickness be maintained to provide adequate protection over subsequent target explosions? Can aerosol and droplet production be avoided? Issues:

ARIES also examined concepts based on thick liquid walls with heavy ion beams Studies of structural materials choices and limits If a 300 series SS is required as a near-term base line for the design, then Ti-modified 316SS (PCA) should be used. However, it was strongly recommended to consider alternate structural material candidates (FS and SiC/SiC) offering the possibility of higher operating temperature & performance. Aerosol concerns (similar to thin liquids) were highlighted. Flow conditioning and careful nozzle design are needed to control the hydrodynamic source. Studies of ion transport modes indicate several feasible options.

The Robust Point Design shows that a multi- beam induction linac driver can meet detailed target and focusing requirements The goal of this 18-month VNL effort was self-consistency, not optimization for cost. Opportunities still exist to optimize this approach to reduce driver cost and COE Fusion Sci. Tech. 44 Sept. 2003, 266-273. Isometric view illustrating the coupling of final focus magnet array with the chamber (courtesy of Tom Brown, PPPL)

A Z-Pinch IFE power plant concept was developed recently ( see presentation by C. L. Olson )

In addition, a variety of assessment studies are performed to help guide R&D Leak Filtered Dried MELCOR code has been used for IFE safety studies to help guide choice of materials (e.g., hohlraum) and improve safety of plant and target factory designs. Flow between volumes considers friction, form losses and chocking Heat transfer to structures Conservation of mass, momentum and energy for both liquid and vapor phases Considers non- condensible gas effects Aerosol transport and deposition Suppression pools, heat exchangers, valves, pumps, etc. System studies are use to determine impact of advances in science and technology and identify to high leverage R&D. Heavy ion driver. Net power = 1.1 GWe COE for HIF plant: fast ignition vs. conventional central ignition Fast ignition Central ignition Safety and Environmental Economic COE (/kWe)

The future of IFE power plant studies ARIES-IFE was terminated by OFES R&D needs were defined, and are incorporated in the program IFE studies could be revisited if funding becomes available Assessments will continue in the IFE technology program Heavy-ion fusion power plant designs are expected to continue to evolve under the auspices of the VNL HAPL is planning an integrated concept study in Phase-II SNLA is planning to starting a POP phase in FY04, which includes a coordinated, multi-institutional study of ZFE power plants

Part II: Chamber technology R&D

Dry wall chamber R&D is now supported mainly by HAPL Main advantages of dry walls Best hope for direct drive Possibility of accommodating constraints from direct drive target injection/survival and driver propagation MFE/IFE overlap minimizes development costs Can learn from MFE armor R&D results for off-normal operation FW+Blanket see quasi steady-state conditions - full use of MFE design and R&D effort Key Issues Simultaneously satisfy armor lifetime and target & driver propagation requirements Nature of threats (energy transport in chamber) Pre-shot chamber conditions Pulsed thermal and radiation damage effects He implantation Fabrication/bond integrity

Limits on cyclic ion fluence and heating in armor materials: -Tests at RHEPP for ions, XAPPER for x-rays -Thermal cycling in laser (UCSD) and IR (ORNL) facilities He implantation/release and effects experiments and modeling Material development to enhance lifetime -Front runner: W armor and FS structure - Engineered material (e.g. castellated or porous layer) to better accommodate local thermal stress and to enhance helium release -Information on materials behavior is also provided from international MFE R&D programs Experiments and modeling are underway to characterize damage mechanisms and develop improved materials RHEPP experiments (SNLA) ~500 kV, 200 ns, 15 J/cm 2 1 10 100 00.511.522.533.54 Ra W Ra W untreat Ra Mo Fluence (J.cm 2 ) R a (microns) Ablation Depth ( m) F(J/cm 2 ) Net Ablation No net ablation, but surface roughening Threshold for ablation Threshold for roughening

Chamber physics and interfaces with targets and drivers are also studied Threat characterization ( LASNEX, BUCKY) Chamber dynamic response and clearing (SPARTAN) Target and driver interfaces Target survival and transport in chamber Effect of chamber gas on laser propagation In-chamber target tracking and beam steering t = 5 ms T max = 15.5 X 10 4 K t = 50 ms T max = 8.15 X 10 4 K Spartan simulation of gas pressure on final optic shows forces are very small

Blankets for dry and thin-liquid protected walls: beyond the first mm, issues are similar to MFE Beyond ~1 mm, FW sees quasi steady state temperature Beyond ~1 mm, issues for FW/blankets are similar to MFE; can exploit information from international design and R&D programs, e.g. Ceramic breeder, Pb-17Li, Li, Flibe as breeding materials FS and ODS FS as structural material EU Dual Coolant Concept (FZK evolution of an ARIES design)

Thin-liquid protection issues were studied in ARIES Advantages Handles much higher instantaneous heat fluxes compared with solid surfaces. Eliminates damage to the armor/first wall due to high-energy ions. Issues Fluid-dynamic aspects (establishment and maintenance of the film) Wetted wall: Low-speed normal injection through a porous surface Forced film: High-speed tangential injection along a solid surface Chamber clearing Source term: both vapor and liquid can be ejected Super-saturated state of the chamber leads to aerosol generation Target injection and driver propagation lead to severe constraints on the acceptable amount and size of aerosol in the chamber.

Experiments and modeling were performed to characterize droplet penetration depth and detachment time Time [sec] Penetration Depth [mm] Simulation Experiment zozo ss

Film detachment length was studied for various flow conditions 0 20 40 60 80 100 120 140 160 180 050010001500200025003000 Plexiglas ( LS = 70) We x d [cm] Flat Curved = 1 mm1.5 mm2 mm = 0 1 mm nozzle 8 GPM 10.1 m/s 10 inclination Re = 9200

Aerosol concerns are common to all liquid- protected chambers Homogeneous nucleation and growth from the vapor phase Supersaturated vapor Ion-seeded vapor Impurity-seeded vapor Phase decomposition from the liquid phase Thermally driven phase explosion Pressure driven fracture Hydrodynamic droplet formation (flow conditioning) 10 6 Torr 10 1 Torr 1 Torr HC PP FS UCSD work on condensation physics GIT work on droplet ejection

Some chamber materials research qualifies as HED By definition, HED > 10 11 J/m 3 X-ray pulse in HYLIFE: ~10 12 J/m 3 (@3 m) Spinodal decomposition and shock-driven fracture are example of resulting phenomena Spinodal decomposition of Si (Craciun) Liquid fracture from tensile shock reflection

Thick liquid-wall chambers: HYLIFE-II is prime example Thick liquid pocket shields chamber structures from neutron damage and reduces activation Ocsillating jets dynamically clear droplets near target (clear path for next pulse) Lifetime of FW can be greatly extended, possibly for life-of- plant, depending on material choice and liquid thickness Well suited to indirect-drive targets, currently favored by HIF (and Z-pinch) community Preferred liquid: LiF-BeF 2 (Flibe) Oscillating jets form main pocket Crossing jets form beam ports Vortices shield beamline penetrations HYLIFE-II requires several jet and flow geometries:

Key issues and development needs for thick liquid chambers * Key issues: fluid dynamics, high-rep rate operation (condensation, re-establish protective blanket, drops) Development needs Validation of chamber dynamics Recovery of protective blanket configuration in inter-pulse time Recovery of vapor conditions to allow beam propagation/focus and target injection/tracking Tolerable cyclic loading on first-wall Validation of first wall/blanket Material selection (radiation damage life, activation, corrosion considerations, hohlraum material recovery) Maintenance/replacement Design for nozzle replacement and first wall if necessary * Fusion Science and Technology, 44, 27-33 (July 2003).

Substantial R&D has been performed to demonstrate our ability to establish the flows Vortices Highly smooth cylindrical jets Slab jet arrays with disruptions Flow conditions approach correct Reynolds and Weber numbers for HYLIFE-II UCB Re>100,000 UC Berkeley

Example: Results from disruption experiments confirm shock absorbing effect of jet array UC Berkeley Surface Position (mm)

Liquid wall development facilities current and future Current: university experiments on liquid jets, condensation, modeling of fluid dynamics, vapor flow, etc. Next steps: larger scale flow loop(s) with molten salt to test Full-scale jets High velocity injection, nozzles Chemistry and material recovery (e.g., target debris) Cyclic thermal and mechanical loading Neutron effects tests will be conducted in an ETF Liquid response to isochoric heating Tritium breeding Neutron damage testing of materials

Closing remarks: The status of IFE chamber research In IFE, chamber research is well integrated into the overall program. Several chamber options are being developed under different programs in a coordinated way. Opportunities to perform good science abound: Hydrodynamics, phase change physics, radiation transport,materials science, etc.

Extras

ARIES-IFE: An integrated assessment of chambers and interfaces (2000-2003) Characterization of target yield Characterization of target yield Target Designs Chamber Concepts Characterization of chamber response Characterization of chamber response Chamber environment Chamber environment Final optics & chamber propagation Final optics & chamber propagation Chamber R&D : Data base Critical issues Chamber R&D : Data base Critical issues Driver Target fabrication, injection, and tracking Target fabrication, injection, and tracking Assess & Iterate

Depth of Flibe released, R=6.5 m Cohesion energy (total evaporation energy) 2.5 Evap. region 10.4 2-phase region Sensible energy (energy to reach saturation) 0.9 T critical 4.1 Explosive boiling region

List of Publications, IFE Technology Group (October 2001 February 2003) Referred Journals and Conference Proceedings 1.S. I. Abdel-Khalik and M. Yoda, Fluid dynamic aspects of thin liquid film protection concepts, Ibid. 2.N. Alexander, Layering of IFE Targets Using a Fluidized Bed, 2nd IAEA Technical Meeting on Physics and Technology of IFE Targets and Chambers (San Diego, CA), Fusion Science & Technology, 43(3), (2003). 3.Anderson, J. K., Durbin, S. G., Sadowski, D. L., Yoda, M. and Abdel-Khalik, S. I., Experimental studies of high-speed liquid films on downward facing surfaces, 2nd IAEA Technical Meeting on Physics and Technology of IFE Targets and Chambers (San Diego, CA), Fusion Science & Technology, 43(3), (2003). 4.C. V. Bindhu, S. S. Harilal, M. S. Tillack, F. Najmabadi, and A. C. Gaeris, "Energy Absorption and Propagation in Laser Created Sparks," submitted to Journal of Physics B. 5.C. V. Bindhu, S. S. Harilal, M. S. Tillack, F. Najmabadi and A. C. Gaeris, Laser propagation and energy absorption by an argon spark, Journal of Applied Physics 94 (in press, Dec 15, 2003 issue). 6.C. V. Bindhu, S. S. Harilal, M. S. Tillack, F. Najmabadi and A. C. Gaeris, Energy absorption and propagation in laser created sparks, submitted to Applied Spectroscopy. 7.L. C. Cadwallader and J. F. Latkowski, Preliminary Identification of Accident Initiating Events for IFE Power Plants, Presented at the 19 th Symposium on Fusion Engineering, Atlantic City, NJ. 8.J. Dahlburg, Target Fabrication - Its Role in High Energy Density Plasma Phenomena, 2nd IAEA Technical Meeting on Physics and Technology of IFE Targets and Chambers (San Diego, CA), Fusion Science & Technology, 43(3), (2003). 9.C.S. Debonnel, G.T. Fukuda, P.M. Bardet and P.F. Peterson, Control of the Heavy-Ion Beam Line Gas Pressure and Density in the HYLIFE Thick-Liquid Chamber, Presented at ISFNT-6 Symposium in April 2002, Fusion Engineering and Design, 63-64, (2002). 10.C.S. Debonnel and P.F. Peterson, Revisited TSUNAMI simulations for the NIF mini-chamber, presented at the Third International Conference on Inertial Fusion Sciences and Applications (IFSA2003), Monterey, CA, September 7-12, 2003. 11. C.S. Debonnel, S. Yu and P.F. Peterson, Evaporation, Venting, and Condensation for the HIF Robust Point Design, presented at the Third International Conference on Inertial Fusion Sciences and Applications (IFSA2003), Monterey, CA, September 7-12, 2003. 81 journal articles, 18 reports since Oct. 2001

reported by: m. s. tillack with contributions from: f. najmabadi uc san diego w. r. meier lawrence...

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