Planar cryo (deuterium wicked into foam) allow studies of

Richtmyer-Meshkov & Rayleigh-Taylor instabilities with

initial target thickness close to that of a high gain target.

D2

150-200 mm

RF foam with

D2

FAST simulation

RT RM

laser

Initial imposed perturbation

Hybrid x-ray & direct drive

Conventional direct drive design but with a thin high-Z overcoat

High-Z overcoat

(50 to 500 nm thick)

Frozen DT fuel

Ablator

High-Z = high atomic number, e.g. gold or palladium

Laser Direct and Indirect drive have their respective

advantages – is there a way to combine the advantages?

Hybrid approach with symmetric drive may enable

robust ignition and substantial yield on NIF

• Early time x-ray drive reduces laser imprint

• Higher mass ablation rate reduces hydro-

instabliy

Laser light

Initial X-ray drive Later time direct drive

Efficiency of direct drive retained

Thin Au or Pd layer

NRL experiments confirm physics underpinnings of hybrid

approach (1 of 2) -- Streak camera images with and without gold layer.

Tim

e Low laser intensity

( for compression)

High laser intensity

( for acceleration)

X-rays from gold layer

laser

0.4 mm

plastic

plastic +

Gold layer

• Laser is absorbed

near plastic target

• Laser “imprints” on

target.

• Laser is absorbed far

from plastic target

• Minimizes laser

imprint

Laser burns thru

gold layer and

direct drive begins. With gold layer

NRL experiments confirm laser imprint reduction and

suppression of hydro instability with hybrid approach.

• Experiments testing this hybrid approach are ongoing on

OMEGA and have started on NIF.

• NRL simulations support this effort

Nike planar

Experiment

Laser driven instabilities cause problems for ICF and HED

experiments High energy electrons can preheat target impeding its compression

LPI induced scattering reduces laser drive and can spoil symmetry.

42

In addition to higher target performance, use of KrF’s shorter

wavelength light reduces the risk from laser plasma instability.

Predicted threshold for two plasmon decay instability ( EM plane wave analysis):

Ithreshold (2pe ) ~ 80 TkeV/(mm× Lmm) ×1015 W/cm2

LLE and NRL experiments agree with this prediction.

Stoeckl, et al., Phys. Rev. Lett. 90 235002 (2003),

J. Weaver, Bull. Amer. Physics Soc. , 54 No. 15, JO5.8 (2009).

1000

100

10

1

½

osig

nal

20

25

20

5

0

3/2

o

an

d h

ard

x-r

ays

0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2

Laser Intensity (1015 W/cm2)

1000

100

10

1

½

osig

nal

20

25

20

5

0

3/2

o

an

d h

ard

x-r

ays

0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2

Laser Intensity (1015 W/cm2)

Lmm = 120 nm

scale length

Ithreshold Nike

λ =248 nm

OMEGA

λ =351 nm

Nike KrF laser accelerates targets to greater than 1000 km/sec

(0 to 2.2 million miles per hour in a billionth of a second!)

Target velocity versus time

Previous record of 700 km/s achieved on Gekko XII/HIPER glass (351nm) laser at Osaka

Made possible by the high uniformity and high ablation pressure generated by the KrF laser

Target

KrF laser beams Joint experiment with Institute of Laser

Engineering, Osaka University

Tim

e (ns)

10.5µm CH foil Laser

NRL Nike Laser Achieves Spot in Guinness World Records

44

Development Path to ICF

45

Today all funding support in the U.S. comes from DOE-NNSA for

research in support of stockpile stewardship for nuclear weapons.

NNSA also supports an effort in magnetized target fusion that operates at lower compressed density & pressure than ICF but higher than MFE

46

Physics of magnetized target fusion is being explored using Sandia’s Z pulsed power facility

47

Photo of shot on Z

48

How far will NIF go towards ignition?

NIF indirect drive

• Most explored approach

• Impressive recent progress

But

• Physics very complicated

• Small fraction of laser energy on capsule

NIF polar direct drive (utilize indirect drive beams)

• Much more efficient use of laser energy

• Better diagnostic access

• Effort will advance physics of direct drive

• Impressive effort by LLE to implement

But

• Far from the optimum configuration for

direct drive

https://lasers.llnl.gov/about/nif/

Requirements for robust ignition & high yield with MJ class lasers

Maximum energy to

capsule Symmetric direct drive with UV laser light

Minimize laser-plasma

instability

Highly symmetric

implosions

Highly uniform laser illumination & targets

Hybrid approach with high-Z layers

Deep UV laser light , broad laser bandwidth

Minimize cross beam

energy transfer (CBET Laser focal zooming, broad laser bandwidth

NIF has chamber ports to accommodate symmetric direct drive

But

A new facility based on the KrF laser would be superior

• Less risk from hydro and laser plasma instabilities

• Better predicted target performance & less laser energy required

• Capability for much higher shot rates (many per day versus few per day)

Development Path to IFE

51

Tritium

breeding

Reaction

chamber

Electricity

or Hydrogen

Generator target

target factory

Laser

Array

Final optics

Key Parts of a Laser Inertial Fusion Energy Power Plant

Major components are modular and separable

Two laser options for Direct Drive. Both have potential to meet the IFE requirements

Electra KrF Laser (NRL)

= 248 nm (fundamental)

Gas Laser

Mercury DPSSL Laser (LLNL)

= 351 nm (if tripled)

Diode-Pumped Solid State Laser

700 J @ 5 pulses/second with λ=248 nm 60 J @ 10 pulses/second with λ=527 nm

The Electra KrF Laser program developed many

technogies needed for IFE

300-700 Joules, 5 Hz

Effective means to cool laser

gas & diode pressure foils

High efficiency transmission

of E-beam into laser gas

Durable large area

cold cathodes

The High Average Power Laser (HAPL) Program: Integrated program to develop the science and technologies for Fusion

Energy with Laser Direct Drive (1999-2008)

Universities 1. UCSD 2. Wisconsin 3. Georgia Tech 4. UCLA 5. U Rochester, LLE 6. UC Santa Barbara 7. UC Berkeley 8. UNC 9. Penn State Electro-optics

Government Labs 1. NRL 2. LLNL 3. SNL 4. LANL 5. ORNL 6. PPPL 7. SRNL 8. INEL

Industry 1. General Atomics 2. L3/PSD 3. Schafer Corp 4. SAIC 5. Commonwealth Tech 6. Coherent 7. Onyx 8. DEI

9. Voss Scientific 10. Northrup 11. Ultramet, Inc 12. Plasma Processes, Inc 13. PLEX Corporation 14. FTF Corporation 15. Research Scientific Inst 16. Optiswitch Technology 17. ESLI

16th HAPL meeting

Dec 4 & 5, 2006

Princeton Plasma Physics Lab

HAPL generated, and in many cases, “bench tested” solutions for most key components

Final Optics:

High Laser Damage Threshold

Grazing Incidence Metal Mirror

Target Fabrication:

Mass Produced Foam Shells

10 M shots at

3.5 J/cm2

(not a limit!)

Target Engagement:

Glint system: accuracy 28 microns

Developing two chamber concepts Engineered Wall Magnetic Intervention

Axis Polar

cusp (2)

Equatorial

cusp

Axis Polar

cusp (2)

Equatorial

cusp

Estimate Target Cost 16 c each

The first wall of an IFE reactor must survive the “threat” spectrum

from a the target – which is sensitive details of the target design.

Alpha particles penetrate a few microns, form helium

bubbles, and can cause the first wall surface to exfoliate

Chamber concepts to prevent damage from alphas

(pressure from helium bubbles exfoliates surface )

Tungsten “foam” with

cell size small enough

for helium to escape

Axis Polar

cusp (2)

Equatorial

cusp

Axis Polar

cusp (2)

Equatorial

cusp

Magnetic Intervention

Engineered first Wall

Fusion should be developed as a phased program, with well

defined gates to advance to the next phase

Phase I: Basic IFE

Science and

Technology

Phase II:

Develop full size

components

Phase III:

Fusion Test Facility • Demonstrate integrated

physics / technologies for a

power plant.

• Tritium breeding, fusion

power handling.

• Develop/ validate fusion

materials and structures.

• READY FOR PILOT

POWER PLANT

Increasing size

Increasing performance

Decreasing scientific risk

Increasing Industry Partnership

60

Example: development plan for IFE with KrF

500 kJ FTF

Single KrF Laser

Phase I – Complete full performance subscale KrF system

Phase II Develop full size components

• Single 5 Hz 18 kJ KrF laser beamline

• Target fabrication /injection /tracking

• Chamber, optics technologies

• Refine target physics

Phase III Fusion Test Facility (FTF) 250 MW Fusion (thermal) power

• Thirty 18 kJ KrF laser beamlines

• Show integrated physics / technologies

• Gain (about) 100

• Tritium breeding, power handling

• Develop fusion materials /structures

Phase IV Prototype Power plant(s)

• Electricity to the grid

Chamber

30 KrF Lasers

The FTF Chamber (conceptual)

GIMM

1.8/3.4 J/cm2

Reaction Chamber

5.5 m inner radius

= 3.2 dpa/yr*

Lens/window

1.0 J/cm2

Laser beam cluster

TARGET

Containment vessel

13 m inner radius Conservatively large radius to first wall

Introduce test materials closer to reaction

(10 - 50 dpa/yr)*

*dpa assumes 70% availability, 250 MW Fusion Power, 70% in neutrons

Coal-fired and KrF laser fusion power power plants have a need for pulsed electron beams.

Electra experiments indicate shorter duration

electron beams are more efficient at

removing Nox from synthetic flue gas.

KrF electron beam technologies are being developed for fossil fuel pollution control

See: http://www.nrl.navy.mil/media/news-

releases/2014/with-electron-beams-nrl-to-clean-up-

nox-emissions-from-coal-power-plant

NRL has a Cooperative Research and Development

Agreement with Zerronox Corporation to pursue solutions

for reducing NOx from coal-fired power plants and other

combustion-based energy sources. Further developing the

pulsed electron beam and implementing a working system

is additionally supported by their parternship with a large

power company.

64

Summary & Discussion

Physics and technology of laboratory fusion is progressing but remains

challenging

Inertial fusion provides a fundamentally different approach to magnetic

Is fusion energy needed? When?

There needs to be more support for creative approaches if we indeed desire

practical fusion energy this century.

Nuclear power will eventually be the only option for high density central

power production.

References and acknowledgements

A Laser Based Fusion Test Facility, S. P. Obenschain, J. D. Sethian, A. J. Schmitt, Fusion Science and Technology / Volume 56 / Number 2 / August 2009 / Pages 594-603 Fusion Technology Plenary / Eighteenth Topical Meeting on the Technology of Fusion Energy (Part 2)

Laser Acceleration of targets to record speeds (>1000 km/sec) http://www.nrl.navy.mil/media/news-releases/2014/nrl-nike-laser-achieves-spot-in-guinness-world-records

Capacity of NRL Nike KrF facility to zoom high energy laser focus (needed to follow ICF capsule implosion: http://www.nrl.navy.mil/media/news-releases/2013/nrl-nike-laser-focuses-on-nuclear-fusion

Clean-up of fossil fuel power plant emissions using technology developed for laser fusion energy: http://www.nrl.navy.mil/media/news-releases/2014/with-electron-beams-nrl-to-clean-up-nox-emissions-from-coal-power-plant

How will nuclear fusion develop in a carbon-free world? http://www.thehindu.com/opinion/blogs/blogs-the-copernican/article4206415.ece http://fusionpower.org/ http://nnsa.energy.gov/aboutus/ourprograms/defenseprograms/stockpilestewardship/inertialconfinementfusion

65

Thanks for permission to utilize material from previous ICF presentations to:

• Dr. John Edwards, Lawrence Livermore National Lab

• Dr. Daniel Sinars, Sandia National Laboratory

• Dr. Craig Sangster, University of Rochester, Laboratory for Laser Energetics