IFE TARGET FABRICATION AND INJECTION

Transcription

1 IFE TARGET FABRICATION AND INJECTION 1951 µm 1690 µm 1500 µm 0.8 µm of CH + 5% Au CH (DT) 64 Fuel DT Vapor Fast Gas Valve Gas Reservoir Target Loader Gun Barrel Transport from Target Factory Rotating Shield Vacuum Pumping Sabot Catcher 1 cm Tracking Stations Recovery of Sabots Blanket Vacuum Chamber IFE Direct Drive Targets IFE Indirect Drive Targets IFE Target Injector Concept K.R. Schultz Director of Inertial Fusion Technology General Atomics SEAB Task Force on Fusion Energy Lawrence Livemore National Laboratory May 26, jy

2 TARGET FABRICATION AND INJECTION ARE PART OF THE IFE COMMUNITY S PHASED DEVELOPMENT STRATEGEY Next Step: Decide at end of Phase l if and how to proceed to an IFE Integrated Research Experiment (IRE) During Phase I, before the IRE decision, we must show that a credible pathway exists for low cost IFE target fabrication and accurate target injection and tracking Inertial Fusion Energy (IFE) Development Stratagy A Look Backward from the End Game Investment Economic (or no-go!) Total project cost $3B. Phase III Total project cost <$2B. Phase III $80M - 120M/yr Engineering Test Facility - ETF - National Ignition Facility - NIF - and ignition program (Separately DOE/DP funded) Attractive, Commercial IFE Power Plant? IFE Demo?? Integrated Research Experiment(s) - IRE - (Lasers and/or ions) Supporting power technologies for the Demo Decision Year ~ 2040 ~ 2025 ~ 2012 Advanced driver and target R&D. Supporting technology R&D? ~ 2003 Phase I ~$50M/yr Target design and Technology R&D Krypton Fluoride Lasers Diode- Pumped Solid State Lasers Heavy Ion Beams /rs

3 CREDIBLE TARGET FABRICATION AND INJECTION ARE NEEDED FOR IFE Design studies show plausible manufacturing and injection processes and reasonable costs We must demonstrate: Technical feasibility of approaches Accuracy can meet requirements Survival of targets during injection Reliability of providing ~5 targets/ second, 24 hours a day, >300 days/year Low cost of production including labor, capital, materials and disposal We have now begun to address these issues Need to show a credible pathway to IFE exists during Phase I, before investing in the IRE Design Studies: Target factory costs Unit cost Typical Specifications $50 90M /target Capsule out-of-round 0.1% Ablator thickness 1% Outer surface smoothness 200 Å Inner surface smoothness 1 µm Capsule centered in hohlraum 25 µm Allowed T after layering 0.5 K Location at shot time (indirect) (direct) ±200 µm ±20 µm Reliability 99%

4 CURRENT ICF TARGETS MEET STRINGENT REQUIREMENTS FOR FABRICATION, DT LAYERING AND ALIGNMENT ICF capsules must meet strict sphericity, concentricity and surface finish standards: CH+5%O %Br NIF standard (1.05 g/cc) 10 4 DT (0.25 g/cc) µm 950 µm 870 µm nm DT (0.3mg/cc) NIF CH Capsule Mode Number Prototype NIF Capsule Power Spectrum NIF Indirect Drive: Out of Round: <1 µm W <2 µm Surface Roughness: <0.2 µm rms (l > 2) DT Ice surface roughness <1 µm rms Location to ±5 cm Alignment to ±6 µm Natural beta layering provides DT ice layering; requires a very uniform thermal environment (±0.1 K control, ±25 µk uniformity) These requirements have been met for Nova and Omega, and success is expected for ignition on NIF in jy

5 IFE WILL HAVE SIMILAR SPECS AND WILL NEED LOW-COST MASS PRODUCTION Larger target size makes accuracy more difficult but we have achieved specs to date Nova: 0.5 mm, Omega: 1.0 mm, NIF: 2 3 mm, IFE: 4 5 mm Larger size may allow relaxed specification Current ICF Target cost ~$2500 each due to: Few-of-a-kind designs constantly changing High development cost est. 10% actual production Small scale production batches of ~5 25 targets Labor-intensive fabrication process for ~103/year Extensive characterization each individual target has a pedigree IFE Targets must cost 25 each Few designs, few changes Continuous production processes Fully automated fabrication Characterization only for statistical process control NIF 2 mm Omega 1 mm Nova 0.5 mm ~5 targets/second are needed 108/year Learning curve progress ratio of 0.66 to meet goal is reasonable

6 IFE CAN BUILD UPON ICF TARGET FABRICATION TECHNIQUES Foam Shells 2 mm High-Z coating Wetted DT foam DT ice DT gas Overcoated Foam Radiative Preheat Direct Drive IFE Target Design DT Ice Layer Metal on Foam jy

7 SOME CURRENT ICF PROCESSES EXTRAPOLATE TO IFE; OTHERS REQUIRE ALTERNATIVES Extrapolate to IFE? Fabrication Step ICF Process Specs? Cost? Alternatives CAPSULES Indirect Drive Direct Drive PAMS-GDP PAMS-GDP Probably Probably Probably not Probably Microencapsulation, Fluid bed coater FOAMS Microencapsulation Probably Yes HOHLRAUMS Machine-plate-leach Yes No Stamp, mold ASSEMBLY Micro-manipulation Yes Yes (Automate) CHARACTERIZATION Extensive pedigree Yes Yes (Statistical sampling) FILLING Permeation Yes Yes Injection fill LAYERING Beta layering, IR and µw enhanced Yes Probably Fluidized bed

8 104 REDUCTION IN HTGR FUEL PRODUCTION COST IS ENCOURAGING FOR IFE µm High-temperature gas-cooled reactor (HTGR) fuel has similarity to IFE capsules Multiple layers of high and low density coatings Stringent quality requirements Over 1011 fuel particles have been produced in a small commercial production facility for Fort St. Vrain reactor HTGR fuel particle with 4 different coating layers Quality control was carried out scale up Bench scale 20 per particle FSV was less than 0.2 per particle Projected commercial per particle Cost (Cents/Particle) Cost reduction was ~104 due to IFE Targets ($) HTGR Fuel Particles Bench Pilot Scale Scale 60 s 70 s... Indicates that low cost IFE targets are not out of reach, but greater precision will be required Current cost ~$2,000/target Initial cost ~20 cents/particle FSV 80 s Projected 10 s 20 s HTGR 00 s Scale-up and Learning (Time) 30 s Projected IFE-Target Cost (Dollars/Target) by statistical means Production yield was ~90% 40 s

9 NEXT-STEP DEVELOPMENT PLANS FOR IFE TARGET FABRICATION Phase l: Work with target designers and power plant studies to select promising designs, optimizing gain, robustness and cost Develop materials for IFE requirements, such as Develop mass production fabrication processes Develop statistical on-line quality control characterization Phase ll: Robust foams, doped ablators, distributed converter hohlraums for HIF Identify suitable industrial technologies Microencapsulation, fluid bed coaters, die casting/injection molding for hohlrams Demonstrate they can achieve the accuracy needed Project they can meet cost goals Bench-scale experiments for production processes Evaluate processes for accuracy, reliability and cost Provide prototype targets to the IRE jy

10 TARGET INJECTION SYSTEMS ARE NOW BEING ADDRESSED Cryogenic target development for Omega and NIF leads the way Targets must be layered (~150 µm thick solid DT) 3 Requires accuracy of ~0.1 K and uniformity of ~25 µk Targets must be kept cold (DT at ~18 K at target chamber center) 3 Heat up of only ~0.5 K allowed to ensure ice integrity Targets are relatively fragile yet must withstand handling Injection studies are promising Nike 60 cm Mirror Actuators Long injection distance (up to ~7.5 m exposed to up to 1500 C) requires velocities that have been demonstrated ( m/s) DT pellet injectors for MFE exceed IFE speeds and injection rate (~5 Hz) 3 MFE accuracy specs are low Indirect/direct drive require accurate placement (±5 mm/5 mm) and tracking (±200 µm/20 µm) of targets based on: 3 Beam steering capability 3 Hohlraum/capsule irradiation uniformity requirements Design studies indicate these specifications can be met with systems using currently available technology

11 THERMAL PROTECTION MUST BE CONSIDERED FOR IFE TARGET, CHAMBER AND INJECTOR DESIGN IFE targets will need DT ice at precise temperature (18 19 K, ±0.5 K) Ice surface smoothness and layer integrity appear to be sensitive to temperature change; T 0.5 K needed after layering The target chamber offers a hostile environment for cryogenic targets; T ~ C, possible gas for wall protection Hohlraums provide protection for indirect drive targets Direct drive targets require trade-off of target albedo, chamber temperature and pressure, and injection velocity. Reflective metal coatings will help T (K) NRL Radiation Heated Ablator Target 18 K Injection Temperature 99% Capsule Surface Reflectivity Ablator Outer Surface 1800 K, 0.5 Torr Xe Allowable Temperature Change OSIRIS 770 K, Vac. Fuel Inner Surface Fuel Outer Surface 1800 K, 0.5 Torr Xe 1800 K, 0.5 Torr Xe Velocity (m/s) /rs

12 STATUS OF IFE TARGET INJECTION AND TRACKING Requirements set by thermal and mechanical robustness of targets Indirect Drive: injection at 100 m/s to ±5 mm, tracking to ±200 µm Direct Drive: without thermal protection, injection at 100 to 1000 m/s may be needed, to ±5 mm, tracking to ±20 µm Gas gun experiments at LBNL have demonstrated the indirect drive requirements can be reliably and repeatable achieved at room temperature and low rep rate Preliminary experiments with surogate direct drive targets in vacuum at room temperature and V 100 m/s also met indirect drive accuracy specs For low albedo targets, direct drive may require development of thermal protection schemes and/or high speed injection and tracking technologies IFE Target Injection Experiment at LBNL

13 NEXT-STEP DEVELOPMENT NEEDED FOR IFE TARGET INJECTION AND TRACKING Phase I: Work with target designers and power plant studies to select promising target and chamber designs and to define their injection requirements Select, design and develop target protection and injection system best suited for direct drive targets Demonstrate injection and tracking of simulated targets at room temperature Measure the thermal response of cryogenic targets and demonstrate methods for thermal protection Phase II: (IRE) Add cryogenic target capability and high temperature surrogate chamber to Phase l injection-tracking system for experiments Provide target injection-tracking system to the IRE

14 IFE TARGET FABRICATION, INJECTION AND TRACKING IS A TEAM EFFORT Being developed as part of the IFE Chamber and Target Technology element of the OFES Virtual Laboratory for Technology by LANL and GA Plans for Phase l will demonstrate that a credible pathway exists for low cost IFE target fabrication, filling, layering, injection and tracking to support the decision at the end of Phase l of whether and how to proceed with the IFE IRE Budget requirements is ~$3M/yr for Phase l 3.0 Target Technology R&D 3.1 Target Fabrication FY00 FY01 FY02 LANL GA LANL GA LANL GA Assess Target Designs X X X Investigate Target Matls & Man Tech X X X Dev Manuf Process for Fab/Fill/Layer X X X X X X 3.2 Target Injection R&D Target Thermal Response X X X Target Injection Accuracy & Tracking X X X Target Acceleration Response X X X Target Property Measurements X X

15 WE PROPOSE TO DEMONSTRATE A CREDIBLE PATHWAY FOR IFE TARGET FABRICATION AND INJECTION To meet IFE target fabrication and injection specifications we will build on ICF experience and on development planned for NIF capsules and DT ice layers Fabrication techniques that extrapolate to low cost mass production have been proposed. Favorable HTGR fuel particle experience is encouraging Target injection and tracking component requirements appear consistent with present technology. Early target injection experiments at room temperature appear favorable. Extrapolation to cryogenic targets is needed IFE target fabrication and injection development is planned within the proposed IFE Technology program During Phase l of the IFE Plan, we propose to demonstrate that a credible pathway exists for IFE target fabrication and injection