Top level overview of target fabrication tasks High Average Power Laser Program Workshop Princeton Plasma Physics Laboratory October 27 and 28, 2004 Presented by Dan Goodin at the

1.What are we trying to do in Phase I? 2.What is the target design? 3.What are the basic target specifications? 4.How is the target fabricated? 5.What are the remaining issues? 6.What’s being done to address the issues? Summary - target fabrication

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. What are we trying to do in Phase I? Address issues about the feasibility of the laser fusion target supply Phase I goals for target fabrication: A 1000 MW(e) power plant will operate at about 6 Hz - about 500,000 targets per day.

Some Expected Direct Drive Specifications Capsule MaterialCH (DVB) foam Capsule Diameter~4-5 mm Capsule Wall Thickness~260  m Foam shell density mg/cc Out of Round<1% of radius Non-Concentricity<1% of wall thickness Shell Surface Finish~20 nm RMS Ice Surface Finish<1  m RMS Temperature at shot~ K Positioning in chamber ± 5 mm Alignment with beams<20  m What is the target design and what are the requirements? (A) “Baseline” Direct Drive High Gain Target Design Divinyl benzene foam shell Polyvinyl phenol overcoat Au/Pd “reflector” on top 1.Baseline target (18K): <0.68 W/cm 2 (970  C and no gas) 2.Foam-insulated: <3.7 W/cm 2 (970  C and K) 3.Foam-insulated (16K): <9.3 W/cm 2 (970  C and K) Permeation barrier ~1  m fill holes (B) “Backup” target with additional “dry” foam to provide insulation Au and/or Pd on top Foam-insulated target is thermally robust

Pressure cell Micro-encapsulation and/or sputter coating (Be) Synergism with ICF programs and decades of R&D Fabricate Capsules DT Fuel Fill DT Fuel Layer Fabricate hohlraum or sabot Load capsule Fluidized bed (CH) Advanced manufacturing methods IFE target fab processes have many common elements - which are derived from ICF experiments Injector demo experiment Inject/Track or insert Existing and major new ICF facilities Z-R OMEGA EP NIF

How is the target fabricated and what are the issues? Advantage = started with ICF experience base injector StepMethods Demonstrated? Remaining Issues Capsules,Microencapsulation,Yes, including DVBNon-concentricity, overcoat polydensationquality, mass-production, meeting specs Metal OvercoatSputter CoatingYes, on small scaleStandard industrial process.. Filling with DTPermeationYes, including DVB shellsOptimize for min. DT inventory Layering  -layeringYes, but on single targetsMass-production demo Cryo HandlingCryostatsYes, but on single targetsPart of layering/injection demo InjectionEM, gas gunRoom Temp. demo now,Accuracy, tracking demo, cryo survival

So the specific issues in this session are………  Capsule non-concentricity - spec is NC <1% of wall thickness  Overcoat - delamination of the overcoat, surface finish of 20 nm  Gas tightness of overcoat & “buckle pressure” for filling  Production process yield improvement  Mass-production methods for 500,000/day - online characterization  DT behavior under heat flux (really injection issue) - understand the limits of DT when exposed to heat flux (impact on chamber design) Batch of ~ mm OD DVB Coating Droplet generator 4 mm dia., 200  m foam layer, CH overcoat, Schroen, Streit DT layer after ~1 W/cm2 for 24 ms Failures during overpressure

The presentations deal directly with these issues……… Five talks/posters: 1) Divinyl benzene (DVB) shells - Diana Schroen, Jon Streit 2) Mass production of IFE targets - Brian Vermillion 3) Solid DT studies - Jim Hoffer, Drew Geller, John Sheliak 4) Poster: DVB foam shells with a dual initiator - Reny Paguio 5) Poster: Foam characterization with ultrasound - Leonard Bond, Morris Good, Diana Schroen GDP Coated RF Foam (related ICF studies) ~ 5 µm PVP DVB Foam W2 Amp DAQ PC Laser Data Laser Photodiode Sensors “Online” feedback & characterization