P. Gobby, A. Nobile, J. Hoffer, A. Schwendt

and W. Steckle

Concepts for Fabrication of Inertial Fusion Energy Targets

Goal of this work is to evaluate the feasibility of fabricating targets for an IFE plant at an acceptable cost

Develop concepts for target fabrication plant: Iterate with target designers, agree on acceptable target materials and

tradeoffs Evaluate processes for fabrication of targets in large quantities at low cost Evaluate the tritium inventory of a target filling facility

Begin demonstrating synthesis of key target materials. Evaluate response of the direct drive cryogenic target to the target chamber during

rapid injection Evaluate capital and operating cost of a target fabrication facility. Define issues for future R&D needed to achieve cost goals.

Target fabrication feasibility and cost is being evaluated for HIF and Direct Drive approaches

Baseline target for HIF is close-coupled target Callahan-Miller, et al.

Baseline target for Direct Drive is NRL target design

The HIF target has many parts, but only a few different types of materials

DT (solid and gas) CH (capsule) Fe foam Al foam Metal-doped CH foam Metal hohlraum D2

CH foams + metals

hohlraums

Fill capsules + layer

Metal foams Pre-assemble

Fabricate capsules

Final assembly & Inject

ORhohlraums

Metal foams

CH foams + metals

Fabricate capsules

Assemble Fill capsules + layer Inject

There are two major approaches in the target fabrication and filling process for HIF (indirect drive) targets

Fill capsules + layerFabricate capsules Inject

Direct drive IFE target fabrication is simple

HIF IFE target filling sequence

“Cold Assembly”

DTDiffusion

Fill

Coolto Cryo Temps

EvacuateDT DT Ice

Layer

AssembleHohlraum

Hohlraum CryogenicAssembly

DT IceLayer

InjectManufacture

Materials

TSH

CAH

“Warm Assembly”

DTDiffusion

Fill

AssembleHohlraum

Coolto Cryo Temps

EvacuateDT

DT IceLayer

TSH

We are using a JIT approach to evaluate minimum tritium inventory required for the fill process

“Cold Assembly”

DTDiffusion

Fill

Coolto Cryo Temps

EvacuateDT

DT IceLayer

AssembleHohlraum

InjectManufacture

Materials

DT inventory during filling

DT pressures during filling

DTDiffusion

Fill

Pre

ssur

e

fill pressure

Time

PressureP(t)P ext(

t)

gfill_outsideMW V Vcapsule−( )?

R Tfill? 0

Nfill

nPext n( )

d?:=

gfill_insideMW Vinner?

R Tfill? 0

Nfill

nP n( )

d?:=

Nfill = (shot rate) x (fill time)

Pext, V

Vcapsule

P, Vinner

fill time

Po{

gfill_TOTAL gfill_outside gfill_inside+:=

HIF tritium inventories have been evaluated for fill in hohlraum and fill before assembly

The above analysis has been performed to evaluate “minimum” tritium inventory - this allows comparison of inventories for different IFE approaches without assuming any engineering approach

“Actual” tritium inventories based on real engineering scenarios will be evaluated in the future

HIF-fill inhohlraum

HIF-fill beforeassembly

Direct Drive

Buckle Pressure 533 atm 533 atm .062 atm

Fill Time 4 hours 4 hours 5 days

Tritium Inventory(beta-layering only) 29.4 kg 1.5 kg 8.9 kg

Tritium Inventory(beta-layering + IR) 28.9 kg 1.0 kg 8.4 kg

Theoretical Minimum tritium inventory (Actual inventories will be higher)

Cool time - 2 hr Evac time - 1 hr layer time - 8 hr IR layer time - 2 hr Fill overpressures

are 75% of buckle pressure

Target fabrication process modeling to produce targets at capacities necessary for an IFE plant is underway

1

WATER-1

B1

S1

B3

OIL-1 S4

B4

B5

S2

S3

S5

Stream HeatersInput Streams100 Liter PAMS Mandrel

PolymerizationReactor

Water Decant Stream

B8

S 8

S 9

PAMS Mandrel/Water Separator

Shell Water WashB6

Ethanol Extraction

S 6

S 7

B9

B10

AIR-1

S 11

S 12

Fluidizd BedPI or GDP

Coat Capsule

S 13

B11

Fluidized BedDrier

S 14

Capsule Manufacture

S 10

S 15

S 16

Uses existing PAMS/GDP technology that is currently used to produce ICF capsules.

Existing bench scale processes are being scaled up using chemical plant design software (Aspen Plus)

We are attempting to demonstrate fabrication of metal-doped foams

• Foams with composition of (CH)0.97M0.03 are the current focus. Foam densities of 11 and 32 mg/cc are needed.

• Metals must have the desired x-ray emission characteristics, acceptable ES&H properties, as well as chemistry and separation characteristics that are compatible with the reactor Flibe and balance of plant.

• We have demonstrated synthesis of polystyrene foam with a densities of 10 mg/cc and 32 mg/cc.

• The lower density foam is very fragile.

• We are preparing to conduct experiments to demonstrate doping of foams with various metals (Au, W, Ta, Hf, Sc, Re, and Bi) using a simple wet impregnation technique.

• We have developed a list of candidate organometallic compounds to be used for doping studies.

10 mg/cc

Critical issues

• Cold assembly of targets will have to be developed to keep tritium inventories low.

• Innovative approaches to DT filling will have a large leverage in reducing tritium inventories.

– Liquid DT injection

– Be foam structural enhancement of capsules

– Improved permeability and strength of capsule materials

• Scale-up of materials fabrication processes is an important issue.