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  D 2

CH foams + metals hohlraums Fill capsules + layer Metal foamsPre-assemble Fabricate capsules Final assembly & Inject OR hohlraums Metal foams CH foams + metals Fabricate capsules AssembleFill 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” DT Diffusion Fill Cool to Cryo Temps Evacuate DT DT Ice Layer Assemble Hohlraum Hohlraum Cryogenic Assembly DT Ice Layer Inject Manufacture Materials TSH CAH “Warm Assembly” DT Diffusion Fill Assemble Hohlraum Cool to Cryo Temps Evacuate DT DT Ice Layer TSH

We are using a JIT approach to evaluate minimum tritium inventory required for the fill process “Cold Assembly” DT Diffusion Fill Cool to Cryo Temps Evacuate DT DT Ice Layer Assemble Hohlraum Inject Manufacture Materials

DT inventory during filling DT pressures during filling DT Diffusion Fill Pressure fill pressure Time Pressure P(t) P ext (t) N fill = (shot rate) x (fill time) P ext, V V capsule P, V inner fill time PoPo {

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 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  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) 0.97 M 0.03 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.