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Overview of Target Status and Challenges
Presented by Dan Goodin at Laboratory for Laser
Energetics Rochester, New York November 8-9, 2005
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A major challenge for us

• Developing a commercial process to produce
  500,000 targets per day is one of the major
  challenges for inertial fusion.

This challenge consists of
1) Making one target that meet specs 3) Making them cheaply
2) Making 500,000/day 4) Getting them into an IFE chamber
Ref APS/DPP Denver, October, 2005
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Target supply specifications are challenging
Some Expected Direct Drive Target
Specifications Capsule Material DVB foam Wall
Thickness 300 ?m Foam shell density 100
mg/cc Non-Concentricity lt1 of wall Out-of-round
lt1 of radius Shell Surface Finish 50 nm RMS Ice
Surface Finish 1 ?m RMS
some specs are changing
Target Team
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Potential HAPL target supply processes have been
identified

• Many processes taken from ICF
• Others developed for IFE.

Sabot
Isothermal environment
1) Fabricate Capsules
2) DT Fuel Fill
3) DT Fuel Layer
4) Inject Target
Micro- encapsulation
Permeation
5) Track Target
Injector
Tracking
Cryogenic Fluidized Bed
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Microencapsulation is used to make DVB foam
shells
1) Fabricate capsules
Oil flow H2O flow
H2O flow
H2O flow
Microencapsulation with a triple orifice
generator is the first step in the process for
IFE target fabrication

• Divinylbenzene (DVB) foam shells for HAPL
  high-gain design
• Polycondensation chemistry Overcoat for gas
  tightness
• Sputter coating High-Z layer for IR reflectivity

We are focusing on meeting specifications for
ignition quality targets - Brian Vermillion will
present.
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2) DT Fuel Fill
DT filling is done by permeation through the
overcoat

• Filling requires slow increase of pressure to
  avoid buckling of the shell
• Modeling with known permeation rates predicts
  lt1 kg is possible
• Elevated temperature permeation shortens fill
  time and decreases inventory
• Ref A. Schwendt et al, Fusion Science and
  Technology, 43, March, 2003

D. Harding, HAPL 10/04
Status (filling HAPL shells) - variable buckle
pressures, microcracks, adding GDPPVP to retain
gas
Bottom line - confirmation of buckle pressure and
fill rate is needed on real samples as they
become available
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3) DT Fuel Layer
Basic principles of layering have been developed,
the challenge for IFE is high-rate
Layering redistribution of DT in the shell
Fill/Layer Demo 24 Diameter
Fluidized Bed (cold gas flow moves targets
rapidly)

• Thicker parts heat more and DT is transported
• ?T 450 ?K for 1 ?wall

• Layering widely studied in ICF program, methods
  still being perfected
• Issues for IFE are mass-production, and lower
  temperature
• Status - cryostat with gas circuit for fluidized
  bed being fabricated

J. Hoffer D. Geller will report on HAPL-
specific studies for DT
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4) Inject Target
Current status of injection and engagement
25 m total length, based on Sombrero design

• Status - we have demonstrated
• Injection velocity of 400 m/s
• Rep-rated operation (6 Hz, burst mode)
• Two-piece sabot separation and deflection
• Membrane support of target in sabot
• Time jitter at chamber center of 0.5 ms
• Target placement accuracy 1? of 10 mm

Gas gun
Feasibility testing for a cryogenic
electromagnet-based, self-centering injector
system (A. Robson, NRL)
Mechanical injector for lower velocities (50-100
m/s)
New variants (e.g., magnetically protected or
no-gas chamber) may allow slower injection..
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5) Track Target
Potential target tracking systems are being
demonstrated

• 1st Generation tracking system is ex-chamber,
  has shown full prediction to 500 ?m (1 ?) at gt400
  m/s (requirement is 20 ?m)
• In-chamber system uses continuous transverse
  tracking along the injection axis - plus Doppler
  for z-position

Poisson spot on CCD
Mark Tillack will talk about the progress in
demonstrating these target tracking
systems. Graham Flint will talk about target
tracking in a power plant.
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A famous speaker in our midst?
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TARGET FABRICATION, INJECTION, ENGAGEMENT
245 - 305 (20) Overview of target status and challenges D. Goodin (GA)
305 - 335 (30) Target Fabrication Progress, including DVB foams, update on mass cryo layering B. Vermillion (GA)
335 - 350 (15) Resumption of LANL DT studies YES theyre back!! J. Hoffer and D Geller (LANL)
350 410 (20) Laboratory Demonstration of In-chamber Target Engagement M. Tillack (UCSD)
410 - 430 (20) Target trackingin a Power Plant G. Flint (GA)
430 - 440 (10) Target Fab/tracking/engagement Discussions All
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Backups
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The top-level requirements are defined
Fab Plant
Target fabrication critical issues 1) Fabricate
500,000/day 2) Fabricate precision targets
economically 3) Fabricate, assemble,
fill/layer/inject at required rates (6 Hz)
APS/DPP SavannahNovember 2004
Power plant studies have concluded that 0.25 -
0.30 targets are needed
Target injection critical issues 4) Withstand
acceleration (up to 1000 gs) during injection 5)
Survive thermal environment 6) Accuracy
repeatability, tracking (?5 mm, ?20 ?m tracking)
Injection heating
Experimental plan for target injection is being
carried out (Nuclear Fusion, 41. May 2001)
Ref UCRL-ID-133629, LLNL, April 7, 1999
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Strategies and pathways in the target supply

• Current target directions
• Define a controlled target baseline for studies
• Make the first ignition-quality target meeting
  specs
• Show feasibility of tracking system concepts
• Move towards mass-production and scaleup.
• Near-term future objectives
• Move to cryogenics with the cryogenic fluidized
  bed (fill/layer)
• Mass-production characterization method
  conceptualization (100 inspection)
• Build a prototypical injector and couple it to
  tracking systems for hit-on-the-fly
• Couple prototypical injector to cryogenic target
  supply
• Long-term future objectives
• 1) Build and proof systems for 100,000s per day