ARIES Team Activities Farrokh Najmabadi VLT PAC Meeting December 4-5, 2000 UCLA Electronic copy: ARIES Web Site:

 Highlights of ARIES Team activities  Progress in ARIES IFE study  Plans for the coming year. Outline

 August 2000: Peer review of ARIES Program Review went very well. Presentations to the Peer Review committee is available in ARIES Web site. OFES will release synopsis of reviewer's reports. Review Panel made several good recommendation to better inform the community of ARIES research: *Better organization of ARIES Web site for easy access to ARIES publications: Already implemented. We have also added a monthly “featured research” item. *More seminars & presentations in the fusion laboratories specially those on detailed work to engage specialists. *Re-institution of ARIES review committees in addition to the town meetings. Highlights of ARIES Team Activities

 October 2000: ARIES-AT technical work completed Documentation in progress. Final report is to be published in J. of Fusion Eng. & Design. Paper at IAEA Fusion Energy Conference. Nine papers, including a plenary presentation at ANS topical meeting.  October 2000: ARIES Fusion Neutron Source Study completed and documented (available on ARIES Web site).  October 2000: Most of the ARIES technical activity is focused on ARIES-IFE which was initiated in parallel to ARIES-AT in July Highlights of ARIES Team Activities

 January 2000: International workshop on SiC composites sponsored jointly by ARIES Team & US material community: Very useful meeting which brought designers and material scientists together. Workshop summary is published in J. of Fusion Eng. & Design.  March 2001: ARIES town meeting on fueling & tritium systems: Wide participation by both MFE & IFE communities, Attendance from EU and Japan is expected.  March 2001: Japan/US workshop on power plant studies and advanced technologies with participation of EU and China Meeting of IEA task group on safety and economic of fusion power. ARIES Team Town Meetings & Workshops

 Highlights of ARIES Team activities  Progress in ARIES IFE study  Plans for the coming year. Outline

 Analyze & asses 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 experiments needed to complete the database ARIES Integrated IFE Chamber Analysis and Assessment Research -- Goals

Project Organization 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) Materials (ANL) Tritium (ANL, LANL*) Drivers* (NRL*, LLNL*, LBL*) Chamber Eng. (UCSD, UW) CAD (UCSD) Target Physics (NRL*, LLNL*, UW) Chamber Physics (UW, UCSD) Parametric Systems Analysis (UCSD, BA, LLNL) Safety & Env. (INEEL, UW, LLNL) Neutronics, Shielding (UW, LLNL) Final Optics & Transport (UCSD, NRL*,LLNL*, LBL) Tasks * voluntary contributions

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

Approach  Six classes of target were identified. Advanced target designs from NRL and LLNL are used as a starting point – both direct- drive and indirect drive designs.  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).

Initial Results of ARIES IFE Study 1.Characterization of Target Yield: New, accurate knowledge of target output (X-rays, debris, neutrons) has established protection requirements. 2.Characterization of Chamber Response: a.Power loads on the chamber walls are identified. b.Engineered chamber surfaces may expand the design window. c.Safety considerations restrict the design window & choices. 3.Target injection. Need to establish chamber environment that is consistent with both first wall protection and target injection and tracking. 4.Driver/chamber interface. Laser optics compatible with the chamber environment as well as propagation of ion beams in dry chambers are being studied.

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

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%) Gammas (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 Total154458

Ion Spectra from Reference Direct and Indirect Target Designs Slow Ions: Fast Ions:

Characterization of Chamber Response: Power & Particle Loading on the Chamber Wall NRL advanced direct-drive targets with output spectra from LLNL & NRL target codes; 6.5-m radius chamber (in vacuum) Most of heat flux due to fusion fuel and fusion products.

Characterization of Chamber Response: X-ray Loading on the Chamber Wall A sequence of BUCKY runs varying the Xe density were per- formed for the NRL target in a 6.5m radius graphite chamber Assumed Target Yields: Ions 29.7 MJ, X-rays 2.33 MJ.

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 mm length 1-2% packing fraction

Pyrolytic carbon at 1278˚C: k400 W/m-K  2250 kg/m 3 C p 1900 J/kg-K Characteristic Diffusion time length Prompt X-ray pulse0.1 ns0.1  m Fiber diameter10-30  m1-10  m Reradiation pulse100  s100  m  = k/  C p  = L 2 /  Enhanced thermal behavior results from extended surface, short diffusion time, & semi-transparency Thermal performance, erosion, plugging and material transport need to be studied A f /A = 4/  (1-  ) L/d ~5 for the ESLI material

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

Heating of Direct-Drive Targets Limits Wall Temperature & Gas Pressure Chamber-based solutions: Low gas pressure Low wall temperature Alternate wall protection Target-based solutions: Sabot or wake shield Frost coating Failure criteria: triple point stress

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 of < /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 Damage that increases absorption (<1%) Damage that modifies the wavefront – – spot size/position (200  m/20  m) and spatial uniformity (1%) Two main concerns:

Mirrors and transmissive wedges are considered Fused silica or CaF 2 wedges Grazing incidence metal mirror  = 80-85˚ Transverse energy J/cm 2

Reflectivity Degradation of Damaged or Contaminated Mirrors Is Being Investigated  Concerns include absorption, scattering, interference effects  Thin protective coatings (not “tuned” multi-layer coatings) also under review

 1 m thick dry wall chamber provides lifetime protection for ceramic insulators of adiabatic lens and chamber wall  In addition to blanket, 35 cm thick local shield is needed to protect FF magnets against radiation  Placing final optics at > 25 m from target alleviates damage by streaming source neutrons Magnet shielding is an important driver-chamber interface concern for Heavy-ion drivers Fusion Technology Institute University of Wisconsin - Madison

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)

Highlights of ARIES Team activities Progress in ARIES IFE study Plans for the coming year. Outline

*ARIES resources include 35k in FY00 & 70k in FY01 devoted to socioeconomic work (not included in socioeconomic total). Distribution of Advanced Design Research 1,894* FY00: 2,214kFY00: 2,225k *

 Excellent progress up to date.  Regular presentations and participation by IFE scientists who are not funded by the ARIES program. ARIES program has become an umbrella to share the latest results in IFE technology and discuss trade-offs and issues.  We will continue with our Research Plan  For FY01, 200k of resources shifted to socioeconomic work.  Cuts hurts in two major areas: GA budget is zeroed out. No target injection, tracking, and fabrication expertise in the ARIES program.GA budget is zeroed out. No target injection, tracking, and fabrication expertise in the ARIES program. LLNL budget is cut by 50%.LLNL budget is cut by 50%.  ARIES Team meeting on Dec. 6-8 will consider how to deal with these cuts. Plans for FY01 ARIES IFE