2. September 3-4, 2003/ARR 1 ARIES-IFE ARIES Project Meeting Georgia Institute of Technology, Atlanta, Georgia September 3-4, 2003 Summary of Issues, Results, Findings and R&D Guidance Farrokh Najmabadi and A. René Raffray University of California, San Diego

3. September 3-4, 2003/ARR 2 ARIES Integrated IFE Chamber Analysis and Assessment Research Goals: 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 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, we divided the activity based on three classes of chambers: -Dry wall chambers; -Solid wall chambers protected with a “sacrificial zone” (e.g. liquid films); -Thick liquid walls. We researched these classes of chambers in series with the entire team focusing on each concept. ARIES core team + contribution from a number of other players in the field.

4. September 3-4, 2003/ARR 3 Example Results from ARIES-IFE Effort on Solid Wall Chambers Evolution of parametric design window for carbon armor in a 6.5 m radius chamber for the 154 MJ direct drive target -Armor survival (including time of flight effect) -Laser breakdown constraint -Target survival

5. September 3-4, 2003/ARR 4 Example Results from ARIES-IFE Effort on Thin Liquid Wall Chambers Vapor and aerosol mass histories for a 6.5 m chamber with a flibe wetted wall exposed to the photon threat spectrum of the 400 MJ indirect-drive target -Potentially major effect on choice of mode of transport and focusing of heavy ion driver based on pre-shot chamber gas density - Neutralized ballistic transport: <1 mtorr -Channel transport: <1 torr. -Self-pinched transport: < 100 mtorr. -Need better understanding of aerosol behavior including coagulation at wall 20 mtorr 100 mtorr 500 mtorr 200 mtorr 800 mtorr

6. September 3-4, 2003/ARR 5 ARIES-IFE Effort on Thick Liquid Wall Chambers Indirect-drive target -material choice -constraints on chamber conditions Heavy-ion beam -study of transport modes -requirements on chamber conditions Liquid wall ablation mechanisms -evaporation, explosive boiling -spalling Chamber dynamics -aerosol formation and behavior -condensation and chamber clearing Liquid jet reformation and droplet formation Shielding of driver components - final focus magnet Choice of chamber structural materials Major Processes and Areas of Study

7. September 3-4, 2003/ARR 6 Indirect Drive Target Key Issues -material choice -constraints on chamber conditions Results and Findings -single use better than recycling -window of material choice exists -in-chamber tracking not needed for gas densities < ~ 1g/cm 3 in a 3 m chamber R&D Guidance -final selection requires overall system study Documentation -partly in wetted wall paper -material choice to be included in overall thick liquid wall paper

8. September 3-4, 2003/ARR 7 Heavy-Ion Beam Driver Key Issues -mode of transport -constraints on chamber conditions Results and Findings -neutralized-ballistic transport is main approach but tight constraint on vacuum (1 mtorr) -pinch transport are higher risk, higher payoff alternatives (channel: 100 mtorr, self-pinch: 1 torr) but need to improve transport efficiency -not much flexibility in relaxing requirements on chamber conditions R&D Guidance -need focused modeling & experimental studies of assisted-pinch and self-pinch transport for further evaluation and improvement Documentation -assisted pinch transport paper already prepared? -possible self-pinched paper to be added? -material choice to be included in overall thick liquid wall paper

9. September 3-4, 2003/ARR 8 Liquid Wall Ablation Mechanisms Key Issues -evaporation and explosive boiling -shock-wave induced spalling Results and Findings ->~100  m of ablated thickness due to explosive boiling in flibe at 0.5 m from center --> leads to large impulse and shock wave -will shock wave be dampened as it traverses the thick liquid jet? -for free liquid jet, fracture occurs at the back of the jet following rarefaction wave formation -will spalled material be cleared as pocket reforms or will it reach region outside the pocket and possibly affect driver transmission? -vapor cloud from photon energy deposition will absorb most of the debris ion energy reducing the total amount of evaporated liquid R&D Guidance -need combination of experimental and modeling studies to better understand and evaluate mechanisms under IFE like conditions -experiments in facilities reproducing IFE photon energy deposition and time scale such as in a laser facility Documentation -full journal paper being prepared -also briefly summarized in town meeting paper

10. September 3-4, 2003/ARR 9 Chamber Dynamics Key Issues -aerosol formation and behavior -condensation and chamber clearing Results and Findings -need to prevent debris accumulation in beam access region -need condensation surfaces for droplets ablated from inner surface of the pocket and venting through jet array R&D Guidance -aerosol behavior in out-of-pocket region needs to be better understood -comprehensive model required including ablation source term, gas dynamics, condensation and aerosol formation and dynamics -condensation dynamics for prototypical material and conditions needs to be studied experimentally Documentation -as part of town meeting paper

11. September 3-4, 2003/ARR 10 Liquid Jet Dynamics Key Issues -liquid jet reformation -droplets formation Results and Findings -possible droplets formation from criss-crossing series of jet could lead to unacceptable aerosol densities affecting driver transmission R&D Guidance -Combination of scaled experimental and modeling studies to better understand droplet formation and behavior in a chamber-like jet geometry Documentation -partly in overall thick liquid wall paper -fully described in separate paper?

12. September 3-4, 2003/ARR 11 Shielding of Driver Components Key Issues -final magnet shielding Results and Findings -should liquid shield be replaced by solid shielding block? R&D Guidance - Documentation -as part of overall thick liquid wall paper

13. September 3-4, 2003/ARR 12 Structural Material Assessment Key Issue -Choice of structural material for thick liquid wall chamber of HYLIFE IFE power plant Results and Findings -Initial choice of 304SS to alleviate need for advanced structural material development. However, this raises possible swelling, activation and He embrittlement concerns -Swelling and activation issues could perhaps be alleviated by compliant design and drastically reducing Nb and Mo impurities -He embrittlement issue and thermal creep limits would seriously impact the operating temperature window (<~550C) when utilized in conjunction with a flibe blanket - Recommendation that other structural materials (in particular ODS FS) be considered for power plant application R&D Guidance -R&D info on advanced structural material, including ODS FS Documentation -already documented as a UCSD technical report -part of overall thick liquid wall paper

14. September 3-4, 2003/ARR 13 Suggested List of Papers for ARIES-IFE Study on Thick Liquid Wall 1.Overall thick liquid wall paper: “Title to be confirmed” 2.Chamber dynamics paper based on town meeting presentations and discussion: “Thick Liquid Wall Chamber Dynamics: Key Issues, Existing Models and Experiments, and Future R&D” 3.Paper on ablation mechanisms: “IFE Liquid Wall Response to the Prompt X-ray Energy Deposition:Investigation of Physical Processes and Assessment of Ablated Material” 4.Paper on liquid jet dynamics including droplet formation: (separate or as part of overall paper?) 5. Other paper(s)?

15. September 3-4, 2003/ARR 14 “Thick Liquid Wall Chamber Dynamics: Key Issues, Existing Models and Experiments, and Future R&D” R. Raffray, W. Meier, S. Abdel-Khalik, R. Bonazza, P. Calderoni, C. Debonnel, Z. Dragojlovic, L. El- Guebaly, D. Haynes, J. Latkowski, C. Olson, P. Peterson, S. Reyes, P. Sharpe, M. Tillack and M. Zaghloul Outline (some sections already written) Introduction (~1 page) 2. TLW Chamber Concept and Operation (~2 pages) -General description of TLW concept -Example HYLIFE-II design with HI driver and ID target -Driver and target constraints 3. Chamber/Liquid Wall Dynamics (~5-7 pages) Describe mechanisms with illustrative analytical results (as needed) -Liquid wall response to threats and early chamber dynamics (to ~1 ms) -Chamber clearing mechanisms (to ~100 ms) 4.Existing Models (~5-7 pages) (capabilities to simulate mechanisms described above, example results and planned improvement) (~0.5-1 page per model) 5.Existing Experimental Facilities (~5-7 pages) (capabilities to simulate and measure mechanisms described above, 6. R&D Needs 7. Conclusions

16. September 3-4, 2003/ARR 15 “IFE Liquid Wall Response to the Prompt X-ray Energy Deposition:Investigation of Physical Processes and Assessment of Ablated Material” M. Zaghloul, R. Raffray, and the ARIES Team Outline (paper being written) 1.Introduction 2.X-ray Energy Deposition - X-ray Spectra - Photon Energy Deposition in The Cavity and Wall - Cold Opacities of Candidate Materials - Profiles of the Percentage of Energy Deposition in the Cavity and Wall 3.Wall Response (Physical Processes and Material Removal Mechanisms) - Thermal Response and Phase Transitions - Normal (Surface) Vaporization - Normal Boiling (Vaporization into HeterogeneousNuclei) - Phase Explosion (Explosive Boiling) and HomogeneousNucleation - Mechanical Response and Ruptures - Fractures and Spall 4.Material Properties - Relevant Material Properties of Candidate Materials - Theoretical Spall Strength and EOS 5.Modelling Approaches - Volumetric vs. Kinetic - Justification for the Volumetric Approach 6.Scoping Results - Results for different ablated amounts -Pb, flibe - Comparison with ABLATOR 7.Discussion and Conclusions