Heavy Ion Fusion-a Future Perspective

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Heavy Ion Fusion-a Future Perspective
E. Michael Campbell PPPL, June 7, 2004
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Presentation Outline

• Present Fusion landscape
• Why HIF
• Challenges
• Opportunities
• Path Forward

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Fusion Facts

• No Administration commitment to rapid development
  of Fusion energy
• Budget deficit is increasing problem (approaching
  of GDP seen in late 1980s) and no cold war
  windfall
• War, Homeland security are priorities
• Energy Priorities are nearer term solutions
• Hydrogen (Hydrogen already at 11 Mtons/year and
  annual growth is 10)
• Fission
• Viewed as Science Program with energy ST
  deferred to after Burning plasmas or Scientific
  feasibility demonstrated

NGNP at INL
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Fusion Facts (contd)

• ITER and not IFE initiative will be OFES focus
  for next decade
• IFE not supported (we cant afford two
  approaches today) by DOE, OFES or OMB
• OFES and OS view is ICF/IFE is NNSA (NNSAgtgtOS)
  responsibility
• OFES priority after ITER is to better exploit
  existing facilities (present run time on 3 major
  OFES facilities is 14 weeks)
• Some OS interest in High Energy Density Physics

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ICF ST advances, funding and controversy are
made possible by its Multiple Missions HIF lies
in the Energy and ST plane
National Security
Stockpile Stewardship
ICF
Energy(National Security)
Science/technology
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An IFE initiative should be catalyzed by Ignition
and High Performance Implosion Results

• Ignition will catalyze IFE interest and may lead
  to broad support for an IFE initiative
• ICF/IFE community must maintain ignition focus on
  NIF (2010)
• Implosion Experiments will have an impact if
  successful
• Cryogenic, low ?, DT Direct drive implosions on
  Omega (2006)
• Integral Fast Ignition experiments on FIREXI and
  Omega-EP (ZR and PW?)
• Implosions on Z

And HIF.
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The Motivation for HIF has not changed

• HIF accelerators have attractive efficiency,
  rep-rate and durability for IFE
• Large accelerator community experience that is
  relevant
• Focusing optics are more robust to fusion chamber
  environment (radiation/debris) than lasers
• lt 4? illumination for targets allows for
  neutronically thick liquid walls
• NNSA indirect target physics program (and FI
  research (OFES NNSA))

BUT
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HIF Development faces significant challenges

• Development path is costly and has not been
  viewed as symbiotic with other ICF/IFE programs
• Little/no target experiments
• Advantages are too far off to motivate IFE
  support today
• Competition from HEDP facilities

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What Would Marshall say?
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Innovation and a broad program approach will
position HIF for a future IFE initiative

• Accelerator
• Increase modularity (reduce unit size)
• Beam manipulations in space and time (like
  lasers!)
• Lasers
• temporal pulse shaping
• CPA (extreme temporal compression -103-104)
• Phase plates and deformable mirrors
• Pulse Power developing analogous capabilities
• Develop average power experiments
• Target design and fabrication
• Advanced simulations
• Targets to compensate for driver limitations
• Fast Ignition
• Develop average power experiments

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Innovation and a broad program approach will
position HIF for a future IFE initiative

• Utilize existing facilities
• Implosions to exploit HIF relevant concepts
• Symmetry control (Shims)
• Low temperature ablators ( BeCu)
• Rad-Hydro with foams
• Ions from short pulse lasers
• Ion-plasma interaction
• Neutralization physics (?)
• Source development required!
• Synergistic Engineering Physics and technology
  with Pulse Power
• Neutronically thick liquid walls
• Reactor concepts
• Driver technology

There is time to innovate.
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IFE requires
Drivers
OMEGA EP Nike,Trident,..
Z-R
NIF
3D rad.-hydro Simulation of igniting target
Simulations
Target ST
Double shell target
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Accelerators
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Improved HIF Beam Manipulations are required !
Pulse Shaping for Robust HIF Point Design
(Indirect Drive) 120 beams, 7MJ
Laser Pulse Shaping (Direct Drive) 60 beams 2 MJ
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Innovations
Beam Production
Longitudinal Compression
Accel-decel injector compression
Neutralized drift compression
Transverse Focusing
Transport
Solenoid transport of large-perveance heavy-ion
beams
Plasma lens, Plasma channel pinch transport
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LSP simulations of neutralized drift and
focusing show significant spatial and temporal
compression
R(cm)

• Axial compression 120 X
• Radial compression to 1/e focal spot radius lt 1
  mm
• Beam intensity on target increases by 50,000 X.

Z(cm)
(cm)
3.9T solenoid
Ramped 220-390 keV K ion beam injected into a
1.4-m long plasma column. Background plasma at 10
times beam density (not shown).
Experiments are essential to validate concept!
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Targets
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IFE has benefited from Innovation in Drivers,
Physics, and Target Fabrication Target design
and fabrication(graded BeCu ablators and fill
tubes)
A small fill tube
Graded Cu dopant In Be shell
Increased Hydro stability
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HIF can benefit from Innovation in Target Design
and Fabrication (Shims to control symmetry)

• Target design and Fabrication can compensate for
  Driver Limitations (3D Rad-Hydro Codes are
  required!!!)

HIF
Z
Shims

• Experiments are underway at Z to validate
  concepts
• Future Experiments on Omega and NIF

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Fast Ignition Concepts for HIF and Z are similar
Ignitor Beam
Pulse Power FI Concept
HIF FI Concept (120 ev radiation Implosion)
Final Shell position
Initial shell Position
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Polar Direct Drive on NIF is an example of
non-spherical initial conditions that may lead
to ignition/gain imploded fuel assemblies)
Baseline Approach Move the Beams!
New Approach Re-point the Beams!
Multi-Dimensional Calculations and 192 beams make
this possible!
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Ions From UUL
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Protons and ions are accelerated in relativistic
laser-solid interactions by three principal
mechanisms

• III. Target Normal Sheath Acceleration
• Ei 10 x Te
• Electrons penetrate target form dense sheath
  on rear, non-irradiated surface
• Strong electrostatic sheath field ionizes
  surface layer (Eo kT / eld MV/mm)
• Rapid (ps) acceleration in expanding sheath
  produces very laminar ion beam

II. Front-surface charge separation Static
limit Ti Te
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Laser-Ion diodes have very interesting
characteristics but need development
50 mm W 1 mm CaF2 (900O C)
20 J, 350 fs 1.054 mm
Laser-ion diodes

• Transverse emittance lt 0.006 p mm-mrad (
• Longitudinal emittance lt keV-ns (velocity
  correlated)
• Energy spread 100
• Bunch charge 1011 1013 protons/ions
• Source diameter 50 mm (fwhm)
• Charge state purity gt80 He-like
• Particle current gt100 kA (at source)
• Rep-rate determined by laser driver
• Laser-ion efficiency gt 1 (4-20 observed
• Neutralization 100

4 conversion of laser energy to F7 ion beam
observed !!
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PW IONs can be focused
50 mm
200mm
gt400mm
Streak images of visible Planckian emission
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Al has been heated to 23 ev by a focused laser
produced proton beam
T 23 ev (7 x 105 j/g) (0.2 joules from 10 joule
laser)

• Laser to Proton conversion efficiencies 10 were
  observed at Nova PW
• Next generation of PW (2-3 kJ) may lead to 100ev
  via ion heating

P K Patel et al
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Laser-Ion acceleration should be explored in
conjunction with Heavy-ion Inertial Fusion
program and Fast Ignitor
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Chambers
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HIF and Z pinch employ thick liquid walls enabled
by lt 4 ? target illumination
Xray driven targets
Flibe Jets
Z pinch IFE
HIF
Reactor Physics collaboration should be key
element of Z and HIF IFE research
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Multiple reactor chambers are a feature of Pulse
Power IFE
Z-Pinch IFE DEMO study used 12 chambers,
Symbiosis with HIF?
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Innovation and a broad program approach will
position HIF for a future IFE initiative

• Accelerators
• Target design and fabrication
• Exploit existing Facilities
• Partner with Pulse power for reactor design and
  Engineering
• Become Champion of average power experiments

Always keep sight of the end goal !