1.  Analyze & assess integrated and self-consistent IFE chamber concepts  Understand trade-offs and identify design windows for promising concepts. The research is not aimed at developing a point design.  Identify existing data base and extrapolations needed for each promising concept. Identify high-leverage items for R&D: What data is missing? What are the shortcomings of present tools? For incomplete database, what is being assumed and why? For incomplete database, what is the acceptable range of data? Would it make a difference to zeroth order, i.e., does it make or break the concept? Start defining needed experiments and simulation tools. ARIES Integrated IFE Chamber Analysis and Assessment Research -- Goals

2. ARIES-IFE Is a Multi-institutional Effort Program Management F. Najmabadi Les Waganer (Operations) Mark Tillack (System Integration) Program Management F. Najmabadi Les Waganer (Operations) Mark Tillack (System Integration) Advisory/Review Committees Advisory/Review Committees OFES Executive Committee (Task Leaders) Executive Committee (Task Leaders) Fusion Labs Fusion Labs Target Fab. (GA, LANL*) Target Inj./Tracking (GA) Chamber Physics (UW, UCSD) Chamber Eng. (UCSD, UW) Parametric Systems Analysis (UCSD, BA, LLNL) Materials (ANL) Target Physics (NRL*, LLNL*, UW) Drivers* (NRL*, LLNL*, LBL*) Final Optics & Transport (UCSD, LBL, PPPL, MIT, NRL*,LLNL*) Safety & Env. (INEEL, UW, LLNL) Tritium (ANL, LANL*) Neutronics, Shielding (UW, LLNL) Tasks * voluntary contributions

3. An Integrated Assessment Defines the R&D Needs 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

4. We Use a Structured Approach to Asses Driver/Chamber Combinations  To make progress, we divided the activity based on three classes of chambers: Dry wall chambers; Solid wall chambers protected with a “sacrificial zone” (such as liquid films); Thick liquid walls.  We plan to research these classes of chambers in series with the entire team focusing on each.  While the initial effort is focused on dry walls, some of the work is generic to all concepts (e.g., characterization of target yield, target injection and tracking, etc).

5. Status of ARIES-IFE Study  Six classes of target were identified. Advanced target designs from NRL (laser-driven direct drive) and LLNL (Heavy-ion- driven indirect-drive) are used as references.  Detailed output spectrum from these targets are calculated and used for analysis of other systems.  Analysis of design window for successful injection of direct and indirect drive targets in a gas-filled chamber (e.g., Xe) is completed.  Final focus and transport is under study: Grazing incident metal mirrors for lasers. Focusing magnets for heavy ions and beam transport in a “high-pressure” chamber.

6. Status of ARIES-IFE Study  Six combination of target spectrum and chamber concepts are under investigation: Nearly Complete, Documentation Direct drive target Work started in March 2001 Dry wall Solid wall with sacrificial layer Thick Liquid Wall Indirect drive target Work started in March 2001 *Probably will not be considered because of large number of penetrations needed *

7. Backup Material

8. Reference Direct and Indirect Target Designs NRL Advanced Direct-Drive Targets DT Vapor 0.3 mg/cc DT Fuel CH Foam + DT 1  m CH +300 Å Au.195 cm.150 cm.169 cm CH foam  = 20 mg/cc DT Vapor 0.3 mg/cc DT Fuel CH Foam + DT 5  CH. 122 cm.144 cm.162 cm CH foam  = 75 mg/cc NRL Direct Drive Target Gain Calculations (1-D) have been corroborated by LLNL and UW. LLNL/LBNL HIF Target

9. Energy output and X-ray Spectra from Reference Direct and Indirect Target Designs NRL Direct Drive Target (MJ) HI Indirect Drive Target (MJ) X-rays 2.14 (1%) 115 (25%) Neutrons 109 (71%) 316 (69%) Gammas0.0046 (0.003%) 0.36 (0.1%) Burn product fast ions 18.1 (12%) 8.43 (2%) Debris ions kinetic energy 24.9 (16%) 18.1 (4%) Residual thermal energy 0.0130.57 Total154458 X-ray spectrum is much harder for NRL direct-drive target

10. X-ray and Charged Particles Spectra NRL Direct-Drive Target 1. X-ray (2.14 MJ) 2. Debris ions (24.9 MJ) 3. Fast burn ions (18.1 MJ) (from J. Perkins, LLNL) 3 1 2

11. Ion Spectra from Reference HI-Driven Indirect –Drive Target Slow Ions Fast Ions

12. 1992 Sombrero Study highlighted many advantages of dry wall chambers. General Atomic calculations indicated that direct-drive targets do not survive injection in Sombrero chamber. A Year Ago, Feasibility of Dry Wall Chambers Was in Question

13. Target injection Design Window Naturally Leads to Certain Research Directions Chamber-based solutions: Low wall temperature: Decoupling of first wall & blanket temperatures Low gas pressure:More accurate calculation of wall loading & response Advanced engineered material Alternate wall protectionMagnetic diversion of ions* Target-based solutions: Sabot or wake shield, Frost coating* * Not considered in detail Target injection window (for 6-m Xe-filled chambers): Pressure < 10-50 mTorr Temperature < 700 C

14. Variations in the Chamber Environment Affects the Target Trajectory in an Unpredictable Way Forces on target calculated by DSMC Code “Correction Factor” for 0.5 Torr Xe pressure is large (~20 cm) Repeatability of correction factor requires constant conditions or precise measurements 1% density variation causes a change in predicted position of 1000  m (at 0.5 Torr) For manageable effect at 50 mTorr, density variability must be <0.01%. Leads to in-chamber tracking Ex-chamber tracking system MIRROR R 50 m TRACKING, GAS, & SABOT REMOVAL 7m STAND-OFF 2.5 m CHAMBER R 6.5 m T ~1500 C ACCELERATOR 8 m 1000 g Capsule velocity out 400 m/sec INJECTOR ACCURACY TRACKING ACCURACY GIMM R 30 m

15. Photon and Ion Attenuation in Carbon and Tungsten

16. Temporal Distribution of Energy Distribution from Photons and Ions Taken into Account From R. Peterson and D. Haynes’s presentation At ARIES meeting September 2000. Example Photon Temporal Distribution Temporal Distribution for Ions Based on Given Spectrum and 6.5 m Chamber Debris Ions Time 10ns 0.2  s 1s1s 2.5  s Fast Ions Photons Energy Deposition Dramatic decrease in the maximum surface temperature when including temporal distribution of energy deposition -e.g. T max for carbon reduced from ~6000°C to ~1400°C for a case with constant k carbon (400 W/m-K) and without protective gas, presented at the Dec. 2000 ARIES meeting

17. Example Temperature History for Carbon Flat Wall Under Energy Deposition from NRL Direct- Drive Spectra Coolant temperature = 500°C Chamber radius = 6.5 m Maximum temperature = 1530 °C Sublimation loss per year = 3x10 -13 m (availability=0.85) Coolant at 500°C3-mm thick Carbon Chamber Wall Energy Front Evaporation heat flux B.C at incident wall Convection B.C. at coolant wall: h= 10 kW/m 2 -K

18. Summary of Thermal and Sublimation Loss Results for Carbon Flat Wall Coolant Temp. Energy Deposition Maximum Temp. Sublimation Loss Sublimation Loss (°C) Multiplier (°C) per Shot (m) per Year (m) * 5001 1530 1.75x10 -21 3.31x10 -13 8001 1787 1.19x10 -18 2.25x10 -10 10001 1972 5.3x10 -17 1.0x10 -8 5002 2474 6.96x10 -14 1.32x10 -5 5003 3429 4.09x10 -10 7.73x10 -2 * Shot frequency = 6; Plant availability = 0.85 Encouraging results: sublimation only takes off when energy deposition is increased by a factor of 2-3 Margin for setting coolant temperature and chamber wall radius, and accounting for uncertainties

19. Example Temperature History for Tungsten Flat Wall Under Energy Deposition from NRL Direct- Drive Spectra Coolant temperature = 500°C Chamber radius = 6.5 m Maximum temperature = 1438 °C Coolant at 500°C 3-mm thick W Chamber Wall Energy Front Evaporation heat flux B.C at incident wall Convection B.C. at coolant wall: h= 10 kW/m 2 -K Key issue for tungsten is to avoid reaching the melting point = 3410°C W compared to C: Much shallower energy deposition from photons Somewhat deeper energy deposition from ions

20. Example Temperature History for Tungsten Flat Wall Under 5 x Energy Deposition from NRL Direct-Drive Spectra Illustrate melting process from W; melting point = 3410°C Include phase change in ANSYS by increasing enthalpy at melting point to account for latent heat of fusion (= 220 kJ/kg for W) Melt layer thickness ~ 1.2  m Separation = 1  m

21. Summary of Thermal Results for Tungsten Flat Wall Coolant Temp. Energy Deposition Maximum Temp. (°C) Multiplier (°C) 500 1 1438 800 1 1710 1000 1 1972 500 2 2390 500 3 3207 500 5 5300 Encouraging results: melting point (3410°C) is not reached even when energy deposition is increased by a factor of 3 Some margin for setting coolant temperature and chamber wall radius, and accounting for uncertainties

22. An Efficient Dry-laser IFE Blanket With Low Wall Temperature Is Possible  IFE dry-wall blanket example: ARIES-AT blanket. First wall coated with C armor and is cooled by He. Coupled to advanced Brayton Cycle  Power loadings based on NRL targets injected at 6 Hz.  30% of power is in the first wall. Blanket (e.g. ARIES- AT) Sep. FW Pb-17Li out in He Blanket Pb-17Li (70% of Thermal Power) He FW (30% of Thermal Power) ~50°C IHX Example Case:  For a  T FW of ~100-150°C, the average surface T wall at target injection can be lowered to ~600°C while maintaining a cycle efficiency of 50%

23. Initial Results from ARIES-IFE have Removed Major Feasibility Issues of Dry Wall Chambers  Research is now focused on Optimization And Attractiveness  Trade-off studies are continuing to fully characterize the design window. We are analyzing response of the chamber to  Higher target yields  Smaller chamber sizes  Different chamber wall armor  Un-going activities in:  Engineered Material,  Effect of chamber environment on target trajectory  Final optics  Safety

24. Good parallel heat transfer, compliant to thermal shock Tailorable fiber geometry, composition, matrix Already demonstrated for high- power laser beam dumps and ion erosion tests Fibers can be thinner than the x- ray attenuation length. Advanced Engineered Materials May Provide Superior Damage Resistance Carbon fiber velvet in carbonizable substrate 7–10  m fiber diameter 1.5-2.5-mm length 1-2% packing fraction

25. Laser-Final Optics Threat Spectra Final Optic ThreatNominal Goal Optical damage by laser>5 J/cm 2 threshold (normal to beam) Nonuniform ablation by x-raysWavefront distortion < /3 (~100 nm) Nonuniform sputtering by ions 6x10 8 pulses in 2 FPY: 2.5x10 6 pulses/atom layer removed Defects and swelling induced Absorption loss of <1% by  -rays and neutronsWavefront distortion of < /3 Contamination from condensable Absorption loss of <1% materials (aerosol, dust, etc.) >5 J/cm 2 threshold Two main concerns:  Damage that increases absorption (<1%)  Damage that modifies the wavefront – spot size/position (200  m/20  m) and spatial uniformity (1%)

26. Safety and Environmental Activities in ARIES-IFE Chamber Assessment In-vessel Activation Ex-vessel Activation Waste Assessment Waste Metrics Energy Source Radiological and Toxic Release Metrics Evaluation Decay Heat Calculation Tritium and Activation Product Mobilization Debris or Dust Chemical Reactivity Toxic Material (Performed jointly by INEEL, UW, LLNL)