Gottfried Besenbruch, Lloyd Brown, Tom Drake, Peter Ebey, Jim Hoffer, Haibo Huang, Barry

McQuillan, Farrokh Najmabadi, Abbas Nikroo, Art Nobile, Ron Petzoldt, Rene Raffray, Diana

Schroen, Bob Stemke, Jon Streit, Masa Takagi, Mark Tillack, Brian Vermillion, Tracy Woo

Presented by Dan Goodin

Update on IFE Target Fabrication

High Average Power Laser Program Workshop

Naval Research LaboratoryWashington, DC

December 5-6, 2002

Target Fabrication Topics

1) Target Fabrication and Injection Plan for Next 3 Years- Ron Petzoldt - Target Injection Status- Rene Raffray - Target Survival Modeling

2) “Building 22” Status (GA’s IFE Development Facility)

3) Microencapsulation Scaleup Studies

4) Status of Target Costing Evaluations

5) Fluidized Bed for IFE Target Fabrication (OFES Grant)

talks this afternoonsurvival workshop tomorrow afternoon

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 highDT permeability andIR reflectivity.

Establishedchemistry for foam shells

General AtomicsSchafer Corp

Targets $0.16 each from chemical process plant methodology

General Atomics

Target Injection / Tracking Phase I Goals1. Build an injector that accelerates targets to a velocity to

transverse the chamber (6.5 m) in 16 milliseconds or less.

2. Demonstrate target tracking with sufficient accuracy for a power plant (+/- 20 microns).

TurboPumps

Gun Barrel

TargetCatcher

Target Position

Detectors

Sabot Deflector

RevolverChamber

ExpansionTanks

1. Started Construction of Gas Driven Target Injector2. Demonstrated Concept of Separable Sabot3. Determining needed properties of DT

General Atomics, LANL

Structure of “Target Plan”

Make Foam Shells

Add Seal Coat

Add High-Z Coat

Filling

Layering

Injection and tracking

Survive Injection

Main Process Steps

Characterize

1. Produce foam shells2. Make seal coat

3. Provide high-Z coat

4. Eval surface in a torus

5. Demo mass-prod layering

7. Demo target injection

8. Meas DT response

9. Model target/chamber interface

Adapt shell manufacture to mass

production

6. Process development

Develop mass-prod methods

Initial plant layoutsand equipment

Show economicaltarget supply

Schafer CorpGeneral Atomics LANL GA/UCSD

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Year 1 | Year 2 | Year 3 |

Target Fab/Injection 3-Year Deliverables (FY03-FY05)

Produce initial foam shells/seal coat/high-Z

Capsules

Eval scaleup methodsProd shells w/mass-prod methods

Layering

Eval foam effect

Design and build mass-production layering equip Demo mass-prod layering

Heat flux on filled target

Injection

Upgrade to rep-rated Conduct parametric exps Demo hit-on-fly

Integrated survival model

Process Development

Initial layouts & equip Update with R&D data Show economical targets

Integrated Self-ConsistentTarget Supply Scenario

Meas heat flux effect Meas DT strength

Target Fabrication/Injection Tasks1) Foam shell production (Schafer)

FY03 - Produce, using R&D scale equipment, target quality foam shells meeting requirements for the high gain direct drive target. Provide polymer seal coat on foam shells meeting requirements for the high gain direct drive target.

2) Foam shell overcoat (Schafer)FY03 - Provide polymer seal coat on foam shells meeting requirements for the high gain

direct drive target.

FY04 - Adapt shell making and seal coat processes to mass production; interface with process design studies to show a feasible and economical mass-production pathway.

3) Application of high-Z layer (GA)FY03 - Optimize high-Z over coat for high gain direct drive target target, accounting for

target design, permeability, and reflectivity considerations; demonstrate techniques amenable to mass production.

SchaferCorp

600 Å Pd on PAMS shell

Target Fabrication/Injection Tasks4) Cryo layering #1 (LANL)

FY03 - Measure the surface finish of a DT layer formed in a torus with a foam underlay (to determine the smoothing effect of the foam).

5) Cryo layering #2 (GA)FY03 - Complete a detailed design and initiate procurement of a lab-scale

system to demonstrate layering of direct drive targets by mechanical motion production (e.g., fluidized bed, bounce pan, and/or spiral tube).

FY04 - Complete procurement and install equipment to demonstrate cryogenic layering of hydrogen isotopes on lab-scale.

FY05 - Conduct shakedown and operate lab-scale system to demonstrate mass-production layering method.

Surrogate layering demo

with neopentyl

alcohol

LANL torus

Target Fabrication/Injection Tasks6) Process development and costing (GA)

FY03 - Provide initial definition and layouts equipment for fabrication of direct drive targets. Operate microencapsulation equipment to evaluate scaleup methods and provide shells for other experiments

FY04 - Incorporate continuing target program R&D data into the Target Fabrication Facility (TFF) equipment lists and plant layouts. Operate microencapsulation equipment to parametrically evaluate methods for scale-up.

FY05 - Support the IRE decision process by providing a chemical engineering approach to the TFF and the IRE pilot-plant target factory that is integrated with results from experimental programs. Fabricate foam shells and seal coats using mass-production methods

H2O/PVA

DVB with initiator

Example process

equipment

Target Fabrication/Injection Tasks7) Target injector (GA)

FY03 - Procure components and convert system to rep-rated operation (6 Hz for 12 shots).

FY04 - Complete shakedown of injection and tracking system (gas-gun) in rep-rated mode; refine and optimize tracking system as needed.

FY05 - Complete injection and tracking studies of parametric conditions (velocity, acceleration, gas pressure, etc.) to demonstrate design windows for meeting tracking accuracy requirements of 20 m. Install a surrogate final optics/mirror unit on injection/tracking system and interface to tracking commands to provide an integrated demonstration of high-speed tracking and hitting the target on-the-fly with a low-power laser (with UCSD collaboration).

Injection system components

Target Fabrication/Injection Tasks8) DT response during injection (LANL)

FY03 - Deposit a layer of DT in a torus and observe effect of rapid heat pulse

FY04 - Conduct experiments to determine the ability of DT with foam underlay to survive rapid heat pulse. Measure elastic modulus and yield strength of DT under representative strain rates, repeat with foam-reinforced DT.

FY05 - Measure DT response with rapid IR heating of filled spherical targets.

Foam-lined toruscutaway view, LANL

Target Fabrication/Injection Tasks9) Target/chamber interface (GA/UCSD)

FY03 - Perform assessment of cryogenic materials properties necessary for target/chamber interface modeling. Develop modeling capabilities. Perform trajectory analysis in coordination with injection tasks.

FY04 - Conduct parametric analyses of target response during cryogenic handling and injection; provide feedback to guide R&D.

FY05 - Bring together materials property data, models of target response during injection, and experimental program results to show a workable solution for direct drive target injection.

We’ve moved into the “Building 22” complex Additional 7200 SF lab space

And 6900 SF of office space

GA’s “IFE Development Facility”

Future chem labs

22-T Offices

B22 Lab

Capsule fabricationby microencapsulation

aq DropletgenerationAir dry Non aqueouspolymer solutionAqueous phaseSolid shellAqAqAq Loss oforganic solventAq

Basic schematic of microencapsulation

Microencapsulation is the planned method for making IFE shells Schafer now developing

methodologies for DVB foam GA is interested in scaling this for

mass-production

Finished Cryogenic Target (4.0 0.2 mm OD)

DT Gas

Solid layered DT at ~18K

DT-filled DVB foam shell- CH polymer- 20-120 mg/cc (20%)- 29020 m- 1 to 3 m cell sizes - OOR: 1% of radius- NC: 1% of wall- density to 0.3% 50-100 m

Overcoat (seal)- 1 to 5 m- 1.40.2 g/cc- 50 nm RMS

High-Z coating- 30-100 nm thick- 50 nm RMS- Au/Pd mixtures

We have begun experimental studies for mass-production microencapsulation

Our goal is to show microencapsulation is an efficient and cost-effective method Yield, reproducibility, optimization for cost, etc. Setup equipment to (a) produce shells for other

studies, and (b) to experimentally evaluate mass-production techniques

We started with PS shells (unfiltered solutions)

Photo of some shells made at

GA - Brian

High-speed video for droplet formation

Development is focused on enhancing yield and reliability for mass-production

We have in mind 3 initial modifications Adding a pulser to better control drop formation Replacing handmade glass needles with machined steel Providing a “scaleable” contactor for processing

Changing the contactor size changes process Re-optimize as we make the contactor larger Need alternative contactor design to avoid this scaleup issue

Laboratory scale contactor

~16 cm

~4’

Potential production-scale

Sol-gel fuel production

Machinedneedledesign

Alternative contactor design - a “gas sparger”

Bubbler with frit to allow gentle agitation Once chamber is large enough to avoid wall effects,

then size shouldn’t matter

Gas sparger concept

Water bath to control temperature

First experiments done

Parametric study comparing to rotary contactor Same shells into rotary system and into gas system Shells into 3% PVA/H2O and into DI H2O

Dropping with glass needle so

far

Experimental system components

Assembledunit

View of bubbles/shells

Bubble to shell size ratio of about 65%

IFE target costing studies are being published

… Basic conclusion is that the NRL direct-drive high-gain target can be mass-produced for about $0.16 each

1) “Cost Modeling for Fabrication of IFE Targets”, Rickman and Goodin, accepted for publication in Fusion Science and Technology, printing May 2003. Direct drive target production

2) “The Viability of an Economical Target Supply for Inertial Fusion Energy”, D.T. Goodin, A. Nobile, D. G. Schroen, G.E. Besenbruch, L.C. Brown, J.L. Maxwell, W.R. Meier, T. Norimatsu, R.W. Petzoldt, W.S. Rickman, W. Steckle, J.P. Dahlburg,1 and E.M. Campbell Planned submittal to Nuclear Fusion ~January, 2003 Covering both direct and indirect drive targets

3) “GA-C” type report with details of modeling, appendices, etc. Controlled distribution available upon request Contains the detailed basis for direct and indirect drive target modeling

Fluidized bed GDP coating results

Method is potentially applicable to both indirect and direct drive targets To make high concentricity thick-walled shells for HIF To add “CH-only” overcoat to “smooth” DVB foam shells

Basic concept is to scaleup bounce pan method of coating GDP onto PAMS mandrels Previous work coated ~ 3 m thick Issues with coating rate, frit and particulates, and “arcing”

Recent accomplishments Fluidized without frit (cone) Deposited arcing-free with good rate Obtained thick coatings

1.2 m/h High-quality coatings Maximum 147 m coating

16.8 m GDP on 2000 m diameter PAMS shellwith 35 m wall

Transparent & brownish colored Moderate surface roughness

Made relatively smooth, transparent coatings

AFM spectrum of 16.8 m GDP from fluidized bed

Wyco shows about 28 nm

surface roughness

Target fabrication summary

… The IFE target development issues have been identified and are being addressed by the ongoing work

A “Target Plan” to address direct drive target fabrication and injection issues has been jointly drafted by GA, LANL, Schafer, and UCSD

Microencapsulation equipment Setup and shaken down system Making PS shells for testing purposes Scaleup studies underway with testing of mass-production methods

Target Fabrication Facility (TFF) scaleup studies and costing models are being published/documented

Coating in a fluidized bed has shown potential for high-quality coatings and for higher coating rate operations