C. Adams, N. Alexander, R. Andrews, G. Besenbruch, D. Bittner, L. Brown, D. Callahan-Miller, T. Drake, F. Elsner, C. Gibson, M. Gouge, A. Greenwood, J. Hoffer, J. Kaae, M. Hollins, T.K. Mau, W. Meier, F. Najmabadi, A. Nikroo, J. Pulsifer, G. Rochau, J. Sater, D. Schroen, A. Schwendt, J. Sethian, C. Shearer, W. Steckle, R. Stemke, E. Stephens, R. Stephens, M. Tabak, M. Tillack and the ARIES Team General Atomics, Naval Research Laboratory, Schafer Laboratories, Los Alamos National Laboratory, University of California, San Diego, Sandia National Laboratories, Lawrence Livermore National Laboratory, Oak Ridge National Laboratory Progress Toward Demonstrating IFE Target Fabrication and Injection Presented by Dan Goodin at HAPL Project Review Pleasanton, California November 13-14, 2001 (IFSA2001 Plenary Session Presentation, Paper #1111)

Some recent IFE target fabrication/injection papers and publications.... Contributions and collaborations with people at GA, LANL, NRL, UCSD, LLNL, Schafer, SNL, and ORNL  “Progress Toward Demonstrating IFE Target Fabrication and Injection”, D. Goodin, et al. IFSA-2001 (Plenary Session Talk)  “Reducing the Costs of Targets for Inertial Fusion Energy”, G. Besenbruch et al. IFSA-2001  “Target Injection and Fabrication Possibilities for Fast Ignitor IFE”, R. Stephens, et al. IFSA-2001 (Invited Talk)  “Thermal Control Techniques for Improved DT Layering of Indirect Drive IFE Targets,” J. Pulsifer et al. IFSA-2001  “Concepts for Fabrication of Inertial Fusion Energy Targets,” Nobile, et al. Fusion Technology, Vol. 39, March 2001, 684. “Developing Target Injection and Tracking for Inertial Fusion Energy Power Plants”, Nuclear Fusion, V41, No. 5, May 2001, 527. “Developing the Basis for Target Injection and Tracking in Inertial Fusion Energy Power Plants”, Goodin et al. Accepted for publication in Fusion Engineering and Design. “Design of an Inertial Fusion Energy Target Tracking and Position Prediction System,” Petzoldt et al. Fusion Technology, Vol. 39, March 2001, 678. Target Fabrication Target Injection

Target fabrication, injection, and tracking issues are being addressed in an integrated fashion.... A significant development program will be required to demonstrate target fabrication and injection for IFE  GA and LANL are part of a team addressing the issues of IFE target supply  LANL = lead for fabrication; GA = lead for injection  Close coordination with target designers and IFE community  Must supply about 500,000 targets per day for a 1000 MW(e) power plant  Precision, cryogenic targets Exploiting our experience with ICF targets - similar materials and processes Manufacture of Capsules Target Supply Includes Filling with DT Layering Process Assembling & Cryohandlin g Injection and Tracking

Target fabrication critical issues 1) Ability to fabricate target capsules & hohlraums 2) Ability to fabricate them economically 3) Ability to fabricate, assemble, fill and layer at required rates Power plant studies have concluded that $0.25 targets are needed - reduced from ~$2500 each for current targets “Critical issues” have been identified and agreed upon Target injection critical issues 4) Withstand acceleration during injection 5) Survive thermal environment 6) Accuracy and repeatability, tracking NRL Radiation Preheat Target LLNL Close-Coupled HI Target.... We are addressing issues for both laser and heavy-ion driven IFE targets “Baseline” targets A detailed experimental plan for target injection has been prepared - and is being carried out (Nuclear Fusion, 41. May 2001)

Overview of target designs and potential processes Target Design Rad. Preheat Empty Outer Foam Thick Capsule Foam shell microencapsulation Interfacial polycondensation Sputter-coating Microencapsulation or Coatings in a fluidized bed Cryogenic fluidized bed or In-sabot Gas-gun or Electromagnetic Target Fabrication Filling LayeringInjection Dist. Radiator Foam shell microencapsulation Interfacial polycondensation or injection molding Microencapsulation + Foam Casting/Doping Permeation or liquid injection Cryogenic fluidized bed or In-hohlraum.... There are many other potential paths, but will focus on these today

Microencapsulation studies for IFE are underway  DVB foam shells are being encapsulated at Schafer for the radiation preheat target  Density range of mg/cc  Pores sizes down to ~1.6  m at 10 mg/cc  Interfacial polymerization to make “seal” coat  Direct microencapsulation of polymers  Chemical process modeling and cost estimating DVB beads 10 mg/cc DVB (D. Schroen) …. Scaleup of existing bench-scale processes will be evaluated using chemical plant design software (Aspen Plus) Flowsheet prepared by LANL

A successful high-Z layer for the radiation preheat target is being developed …. Some representative gold-coated flats and spheres have been fabricated and tested High-Z Layer (Au?) Target Design (Z, smooth, uniform) Fabrication (coating, cost) Layering (IR, Joule heating) Injection (stable, reflective) ES&H (hazardous, WDR) Seemingly simple component has multi-disciplinary functions and requirements  Gold was proposed first  Effective in design, easy to coat, high reflectivity  Issue with gold is permeation rate during filling  Permeation through bulk gold is very slow  Experience  thin gold is actually hard to seal Filling with DT

Gold layers were tested for required properties Au target  Prepared Å gold coatings by sputter-coating (very smooth, good mass-production technique)  Measured thickness and uniformity by XRF  Gas permeation slowed by “only” a factor of ~8  Goal to minimize tritium inventory in Target Fab. Facility Sputter-coating gold with bounce pan Excitation X-ray beam Au X-ray fluorescence X-ray detector Au coating Two wall Au fluorescence Polymer shell x-ray absorbance is negligible Side View Eventual beam block for single wall measure ment XRF for thickness and uniformity Angle, deg Au thickness, Å Shell rotated to examine thickness uniformity …. Evaluate alternates in addition to the baseline

Alternative high-Z materials may speed filling …. Full test is to fill target, cool, and measure reflectivity at cryogenic temperatures!  Palladium is a well-known diffuser in tritium applications  Target designers are finding Pd reduces the imprint  Permeation for hydrogen is very high  Reflectivity is lower but may be acceptable (~80% vs 95%)  Concern for pure Pd is phase change (expansion) upon exposure to H 2 (often alloyed with Ag to reduce effect)  Made some Pd flats and spheres for testing  Exposed flats on glass to H 2 - instant wrinkling  Exposed Pd-coated polymer sphere - no visible change Fill 300K Pd4.4 hrs Ta50 days Nb6.6 yrs atm ∆P Calc. for bulk 390 Å Pd on Si, reaction to H 2 exposure 600 Å Pd on PAMS shell - before and after Before DuringAfter

Industrial technologies are being brought to target fabrication  Fluidized beds are well established in industry - GA has reduced costs of coated nuclear fuel particles  Mass-production scaling of “bounce-pan” method used for high-quality ICF shells on PAMS mandrels  Several runs for GDP coating have shown good results - very promising method  Thickness variations (~10%) and surface roughness comparable to ICF Coating Mandrel PAMS Mandrels in Fluidized Bed Fluidized Bed GDP Coating Setup ~ 3 micron thick GDP coating on PAMS.... Fluidized bed technology has a number of potential applications to IFE target fabrication

Nebulizer creates microspray Nebulizer gas flow Additional gas flow Fluidized bed coating zone with screen 2 mm PI Aerosol microspray of polyamic acid solution; 4-8 micron droplet size  Spray coating technology widely used in pharmaceutical industry  Polyimide coatings using a fluidized bed have been made  Wall thickness of a few microns; FTIR shows fully imidized  Currently working on vapor/liquid smoothing.…Industrial technologies such as fluidized beds are needed to reduce the costs of target fabrication An alternative mass-production coating method is solution spray-drying in a fluidized bed ~ 7 micron thick PAA coating on PAMS PAMS mandrel PAA coating 7.3  m

4 mm diameter hemishell ~100 mg/cc, 400  m wall Reduced requirements may allow less-precise processes  Recent results: High-yield capsules tolerate rougher surfaces than low-yield targets  Ablator 10-20X “NIF Standard” (10 to 20 nm)  Inner ice roughness 5-10X NIF (~1  m) CH ablator Advantages Simple process Reproducible process (each shell has same diameter and wall thickness) Status Teflon mold made 100 mg/cc foam shell Easy mold removal Defects at injection port and at equator Ongoing work “Partial” skin on foam hemishell exterior Foam cross section “Partial” skin LLNL targets

Progress in special materials for LLNL target  Distributed radiator target has a number of new materials - low density metal-doped CH and metal foams  Developing low-density foam fabrication methods  Working with designers to simplify materials  “Moral equivalent” of the more difficult materials.... Progress in simplifying the target components! Undoped 30 mg/cc PS foam 2% W-doped 30 mg/cc PS foam Undoped 30 mg/cc 2% Au-doped30 mg/cc Metal-doped PS Foams Nano-powder incorporation Cross section of hohlraum A: AuGd<1% dense B: AuGd100% dense C: Fe0.2% dense D: (CD 2 )Au E: AuGd<1% dense F: Al<3% dense G: AuGd <2% dense H: CD 2 I: Al2% dense J: AuGd4% dense K, L: DT M: BeBr or Polystyrene N: (CD 2 )Au

Target filling and layering methods must be scaled to high throughputs The first full target supply system is at OMEGA  4 filled/layered targets/day 36” I.D. X 40” Tall, 8 trays, 290,000 targets Pressure cell with trays COLD HELIUM FLUIDIZED BED WITH GOLD PLATED (IR REFLECTING) INNER WALL INJECT IR Fluidized Bed Concept for Capsule Layering ASSEMBLED HOHLRAUMS ARE STAGED IN VERTICAL TUBES WITH PRECISE TEMPERATURE CONTROL Tube Layering Concept for Hohlraums.... Development programs to demonstrate low-cost processes for filling and layering

 Highly desirable to minimize T inventory in the TFF (<1 kg)  Model to evaluate effects of target design and filling process parameters  Provide guidance on areas of R&D Modeling to evaluate DT inventory in TFF Work is in progress, but we have demonstrated: Fill Temperature (K) Inventory (kg) Layering Time (hr) Inventory (kg) With shorter fill times, the DT ice layering time becomes the largest contributor to tritium inventory. 8hr layering (beta-layering) 2hr layering 400K INDIRECT DRIVE Results & Status Need to minimize dead-space, maximize temperature, maximize target strength Filling of indirect drive targets in hohlraums results in 30X higher inventories Current best estimates of minimum inventories: -HIF Target - cryogenic assembly0.18 kg tritium -DD Target - 10 mg/cc foam shell1.24 kg tritium -DD Target mg/cc foam shell0.56 kg tritium Fill at 400K 2 hour layering time.... Details of model in Fusion Technology, 39, 684 (2001)

Demonstration of mass layering with a room temperature surrogate instead of hydrogen Basic concept = use a more convenient surrogate to demonstrate fluidized bed layering and evaluate operating parameters Allows use of room temperature characterization equipment Prepared samples by microencapsulation and by injection.... Proof-of-principle demonstration done, next step is to design a cryogenic fluidized bed system IR LAMP Oxalic acid Before  After  Fluidized bed in water bath Neopentyl alcohol Filled thru hole and sealed

In-hohlraum layering is being evaluated  “Thermal Control Techniques for Improved DT Layering of Indirect Drive IFE Targets” - John Pulsifer et al.  FB layering works for ID, but requires rapid assembly few seconds before shot  In-hohlraum layering sequence = fill with DT, cool, assemble, then layer in tubes  Advantages  reduces DT inventory, allows slow assembly, buffer of ready targets Results = calculated T at hohlraum surface; gives ~200  K variation at DT surface (CH ablator) With “gaps” in B layer Stack of hohlraums in cooled tubes Provide a uniform T boundary and a varying radial conductance - to result in desired T profile Design Data Cu rods 4.68 m long 234 hohlraums/rod ∆T top/bottom = 0.1K 0.3 g/s He at 200 psi/rod ∆P = ~10 psi.... But how does this translate to the TFF?

Design calculations show equipment size for in-hohlraum layering is reasonable Design Data 3 hr layering h backlog 18 rods per bundle 18 bundles total 75,600 hohlraums Total He cooling flow = 97 g/s ~1 m 54 s between movements 3 s between movements.... “In-hohlraum” layering can also apply to DD targets

Layering in a sabot can be similar to layering in a hohlraum  A sabot is used to protect the direct drive target during injection  Concept = chain cools ends of sabot and waist made hotter by tailored thermal conductance  isotherms at capsule  For 5 cm links, 5 Hz shot rate and 15 min layering time need 225 m of chain  Chain may be serpentined into smaller volume (10m x 4.5m x 1m) RF plate set and sabot located at every link of chain Cooling wipers Dielectric chain Dielectric sabot RF plates supply Joule heating at random orientations RF E-field direction cycled at each station to maintain layer uniformity As links approach injector, RF power reduced and temperature adjusted to 18.2K

With SNL and others, target systems for Z-pinch driven IFE are being developed.... Design concepts have been prepared indicating time frames for cryogenic target assembly and handling are feasible Flibe-protected ZFE chamber concept Assembled RTL/target in transit Removable lid Target Assembly Station Be capsule Liquid H 2 “buffers” Plant Design Data Rep-rate = 0.1 Hz Yield = 3 to 20 GJ Power = ~1100 MW(e) See “ZP-3, A Power Plant Utilizing Z-Pinch Fusion Technology”, Rochau et al. IFSA2001

Indirect drive target is well insulated by hohlraum materials Direct drive target needs high surface reflectivity to increase the usable reactor wall temperature  With UCSD and the ARIES team, an integrated model of target heating during injection is being developed Target survival during injection - modeling & analyses Excessive heating Asymmetric heating 1.Lower first wall temperatures 2.Lower gas pressures 1.Lower first wall temperatures 2.Lower gas pressures

Target survival during injection - material properties Side view, cross- section of cryogenic torus (windows not shown) DT/Foam Layer Foam cast in torus Exposed DT Uncertainty in response of DT ice to rapid heat flux exposure  experiment being designed Based on techniques previously developed at LANL Cryogenic torus effectively turns the target “inside- out” – exposing the DT ice inner surface for viewing Uncertainty in actual reflectivity of thin high-Z coatings  experiment Allowable reactor wall temperature depends on target heating/survival Fabricated Au samples and measured reflectivity as f(thickness, wavelength) Calculated allowable chamber operating conditions

Target survival during injection - demonstration Strategy and approach –Acquire proof-of-principle data on target injection as soon as possible –Provide a facility to aid in developing practical, survivable targets –Develop and demonstrate injection and tracking technologies suitable for an IFE power plant –Prototype concepts and designs for application in an IRE.... System is in final design stage, procurement in CY02

Summary and conclusions Capsule Fabrication Filling and Layering Injection.... A significant development program for IFE target fabrication, filling, layering, and injection will be required  Filling models are available to guide the R&D programs  Alternative approaches are being evaluated  Initial design calculations are underway  A coordinated program of modeling, materials measurements, and equipment for demonstrations is underway  Methods for fueling of Z-pinch driven IFE devices are being developed  Materials fabrication technologies are now being defined  Exploratory R&D programs are underway - including experiments  Chemical process modeling and cost estimating is beginning  Industrial technologies for mass-production are being applied