The Plan to Develop Laser Fusion Energy John Sethian Naval Research Laboratory July 19, 2002

Lasers and direct drive targets can lead to an attractive power plant… Spherical target Electricity Generator Dry wall (passive) chamber Target factory Modular Laser Array Final optics Modular, separable parts: lower development costs, economical upgrades Targets are simple spherical shells: “fuel” lends itself to automated production Pursuing dry wall (passive) chamber because of simplicity. Others possible Past power plant studies have shown concept economically attractive

Chambers & Materials WISCONSIN: Yield spectrum / Chambers LLNL: Alt chamber concepts, materials UCSD/ANL/INEEL: Chamber dynamics SNL: Materials response x-rays/ions ORNL/UCLA/UCSB/Wisconsin: Materials We are developing Laser IFE as an integrated system. ( 8 Government labs, 7 Universities, 8 Private Industries) Target Fabrication GA: Fab, charac, mass production LANL: Adv foams SCHAFER: DvB foams Direct Drive Target Design NRL- Target design LLNL: Yield spectrum, design Target Injection GA: Injector, Injection & Tracking LANL: DT mech prop, thermal resp. Final Optics LLNL: X-rays, ions, neutrons UCSD: Laser, debris mitigation Target factory Lasers KrF: NRL Titan PSD, SAIC, PPPL, Georgia Tech, Commonwealth Tech DPSSL: LLNL Crystal Systems, Litton, Onyx Corp, Northrup, UR/LLE Lasers Target Fabrication Target Injection Direct Drive Target Design Chambers and Materials Final Optics

The program capitalizes on two main thrusts in DOE Laser Fusion Energy (HAPL) Program Rep-Rate Lasers High Gain Target Design & Experiments Mass Production of Targets Target Injection Final Optics Chambers Fusion Program (Office of Science): System studies (ARIES) Blanket/Breeders Materials Threats to wall (ELM) ICF Program (NNSA/Defense Programs): Single shot lasers Ignition Target Design Target experiments Single Shot Target fab

We are following a three phase program to develop Laser Fusion Energy Phase I: Establish science and technology Start 1999 Phase II Integrated Research Experiments and more start  2006 Phase III Engineering Test Facility start  2014, operating 2020  2-3 MJ, 60 laser beam lines  High gain target implosions  Optimize chamber materials & components.  Generate  300 MW electricity from fusion  Laser facility -full energy beam line hits injected targets  Target facility- inject targets into chamber environment  Power Plant Design  Material Development Target Design-II 3D Modeling High energy (MJ) NIF exp Develop Viable: Target designs, scalable laser tech, target fab/ injection, final optics, chamber Establish: Target physics, Full scale Laser technology, Power Plant design ? Lasers  Electra KrF  Mercury DPPSL Other Comp  target fabrication  target injection  final optics  Chamber/materials ? Target Design-I 2D/3D Modeling Nike, Omega experiments

Phase I R&D areas 1.Lasers 2.Final Optics 3.Chambers 4.Target Fabrication 5.Target Injection/Tracking 6.Target Design and Experiments

Lasers Phase I Goals 1.Develop technologies that can meet fusion energy requirements for efficiency (> 6%), repetition rate (5-10 Hz), and durability (> 100,000,000 shots continuous). 2.Demonstrate required laser beam quality and pulse shaping 3.Laser technologies employed must scale to reactor size laser modules and projected to have attractive costs for commercial fusion energy. KrF Laser (Electra-NRL) DPSSL (Mercury-LLNL) Developed: First Generation Pulsed Power High transmission e-beam window Advanced Solid State Switch KrF Kinetics Code Developed: 160 kW diode arrays Large, high quality crystals Gas cooling of amplifier head 12 J laser light!

Final Optic Phase I Goals 1.Meet laser induced damage threshold (LIDT) requirements of more than 5 Joules/cm 2, in large area optics. 2.Develop a credible final optics design that is resistant to degradation from neutrons, x-rays, gamma rays, debris, contamination, and energetic ions. stiff, lightweight, cooled, neutron transparent substrate 85° Laser Established high damage threshold for grazing incidence aluminum mirror Desired 5 J/cm 2 UCSD Also investigating fused silica

Chambers Phase I Goals 1.Develop a viable first wall concept for a fusion power plant. 2.Produce a viable “point design” for a fusion power plant Establishing a chamber operating window… Portfolio of solutions has been identified, experimental evaluations underway. UCSD Wisconsin SNL ORNL LLNL UCSD Long term material issues are being resolved. EXAMPLE: Tungsten wall No gas in chamber 154 MJ NRL target R. Raffray, UCSD UCSD Wisconsin Example- Ion exposures on RHEPP

There is significant commonality in IFE and MFE chamber requirements Frequency and energy density of ELM’s and IFE conditions are within about one order of magnitude Adapted from R. Raffray, UCSD

Target Fabrication Phase I Goals 1.Develop mass production methods to fabricate cryogenic DT targets that meet the requirements of the target design codes and chamber design. Includes characterization. 2.Combine these methods with established mass production costing models to show targets cost will be less than $0.25. Developed thin Au/Pd coatings with high DT permeability and IR reflectivity. Established chemistry for foam shells General Atomics Schafer Corp Targets $0.16 each from chemical process plant methodology General Atomics

Target Injection / Tracking Phase I Goals 1.Build an injector that accelerates targets the equivalent distance of the chamber (6.5 m) in less than 60 milliseconds. 2.Demonstrate target tracking with sufficient accuracy for a power plant (+/- 20 microns). Turbo Pumps Gun Barrel Target Catcher Target Position Detectors Sabot Deflector Revolver Chamber Expansion Tanks 1.Started Construction of Gas Driven Target Injector 2.Demonstrated Concept of Separable Sabot 3.Determining needed properties of DT General Atomics, LANL

Target Design Phase I Goals 1.Develop credible target designs, using 2D and 3D modeling, that have sufficient gain (> 100) + stability for fusion energy. 2.Benchmark underlying codes with experiments on Nike & Omega 3.Integrate design into needs of target fab, injection and reactor chamber. Integrated high-resolution 2-D Modeling, through burn NRL Omega facility UR/LLE Nike KrF Laser NRL NRL and LLNL are collaborating to evaluate a broad suite of target designs

Example of Integration of requirements: High-Z outer layer helps laser-target interaction physics and helps protect target during injection. Experiment shows 1200 Å Pd outer layer substantially reduces laser imprint Could add unfilled CH foam insulation underneath High Z layer for insulation during injection 1-D Pellet Gain > 100, sufficient for Energy Gain Pd thickness (Angstroms) MJ KrF laser 1.48 MJ KrF laser 0

Goals for Laser IFE Phase II- (Page 1/2) Overall Objective: Establish Science & Technology to build Engineering Test Facility 1. Laser Facility Lasers: Build a full-scale (power plant sized) laser beam line using the best laser choice to emerge from Phase I: (KrF: kJ) (DPPSL: 4-12 kJ) The beam line will demonstrate all the fusion energy requirements, including efficiency, rep-rate, durability, and cost basis Final optics/target injection: Demonstrate the full scale beam line can be steered to hit a target that is repetitively injected into a chamber, with the required precision and optics LIDT durability. Chamber Dynamics: Evaluate chamber clearing models: “Mini Chamber” Chamber materials: Study candidate wall and/or optics materials

Goals for Laser IFE Phase II – (Page 2/2) 2. Target Facility Target fabrication: Demonstrate “batch mode” mass production of fusion class targets. Target Injection: Demonstrate repetitive injection of above targets into a simulated fusion chamber environment. And the target survives. 3. Power Plant Design Produce a credible design for a power plant that meets the technical and economic requirements for commercial power. 4. Chamber and final optics: Evaluate candidate materials/structures in a non-fusion environment. 5. Target Physics: Modeling: Integrated high-resolution 3D target modeling. Experiments: Validate design codes with target physics experiments at fusion scale energies single shot (e.g. NIF) and at lower energies on a rep-rate facility.

Lasers and direct drive targets can lead to an attractive power plant. We are developing Laser IFE as an integrated system: Lasers, target design, target fabrication, final optics, chambers The program capitalizes on two main thrusts in DOE: ICF Program (NNSA/Defense Programs): Lasers, Target design, Target Fabrication Fusion Program (Office of Science): Fusion materials/components, power plant studies We have made significant advances in all areas: Lasers, target design, target fabrication, final optics, chambers We are pursuing a three phase program to develop Laser Fusion Energy Must meet specific goals before going to next phase The Laser Fusion Energy Program