October 19, 2003 Fusion Power Associates

Status of Fast Ignition-High Energy Density Physics

Joe Kilkenny

Director Inertial Fusion TechnologyGeneral Atomics

San Diego, California

Ignition and gain curves for multiple target concepts show the advantages of Fast Ignition

— Fast ignition potentially gives more gain and lower threshold energy then “Hot Spot” ICF but the science and technology are far less developed

FI at NIF

T ρ

Shock heated central spot ignites - a high density cold shell

~ Pc = αρc5/3~

Conventional ICF

Intensity ~1014 - 1015 w/cm2

Fastinjectionof heat

T

r

ρ

-Fast e– heated side spot ignites , a lower density larger uniform

>> fuel ball Pc =

Fast Ignitor

Intensity ~1020 w/cm2

Indirect Drive

Advanced Indirect

Drive on NIF

Fast Ignition has attractive features in addition to high gain at lower total drive energy

• Challenging science and technology• Compression MIGHT be possible with all Drivers

0.53 m , 1.05m (?)• Brightness requirements for compression drivers are reduced

– Radiation temperatures of ~100ev required for compression!• Direct and Indirect target schemes for compression• Innovative target concepts

– one-sided indirect drive– indirect drive illumination ( PDD) for direct drive– asymmetric compression drive configurations

• Target fabrication tolerances are relaxed

NIF produces ~4 MJ at 1.05 m

Heavy Ion Beam Drive

Z-pinch DriveIndirect Laser drive

Direct Laser driveHeavy Ion Beam Drive

ions

Fast Ignition is compatible with all drivers

Innovative target designs are possible

BUTIgnitor laser energy

must be determined!

NNSA is interested too! The photons, electrons and ions from PW lasers can be used to heat and diagnose HEDP plasmas

Multi-kJ PW’s are now planned for OMEGA(EP), Z-R, and NIF

The Z-Beamlet laser is being upgraded to provide a high energy PW laser for use on Sandia’s Z facility

Z-Beamlet multikilojoule laser facility

Z-Beamlet and Z-PW laser

facility

Z z-pinch facility

Z multimegajoule z-pinch facility

• The Z-Beamlet laser will provide a 2-4 kJ, 1-10 psec laser ~ 2007

• A 50-200 J, 0.5 - 10 psec prototype laser system will begin operation in 2004.

High energy radiography and fast ignitor experiments on Z facility

Resistive inhibition needs testing under ignition relevant conditions

Experiments are needed in low resistivity plasmas

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

0.1 1 10 100 1000

Temperature eV

Resis

tivit

y O

hm

m

Current expts

DT fuel

Au cone ??

Ohmic limit in FI

CD1 g/cc

D2

10 g/cc

100 g/cc

Au

CD

Critical Surface

Dense Gold

Coronal Plasma/Gold

Compressed Core

e

US OFES effort addresses all aspects of FI

• OFES support is highly leveraged– Complementary programs– Internal funds – Overseas collaborations

• FI Target design efforts at NNSA funded labs

– SNL - Z - PW– LLE - Omega EP– LLNL - NIF -HEPW

US Fusion Energy program OFES

UC Davis

Princeton

GA

Vulcan

GekkoXII

LULI

LLNL

LLE

SNL

UN,Reno

Ignition target design

Fast Ignition Concept Exploration

OMEGA

Hydro Modeling agrees very well

• Stagnation time, shape

• Compressed density

• Emission from target

• Model does not include mixing of Au vapor with collapsing shell - will measure from excess self-emission

Models may be sufficiently accurately to for target design extrapolations

• Compact mass, ~60 mg/cm2

minimal cone vapor

Electron beam is moderately well directed

Al thickness micron

2500 5000 7500 10000 125000905xray03

180 m

Cu

20m

Al

20 m

0

100

200

300

400

500

600

0 100 200 300 400 500

Al thickness, µm

Spot diameter, µm

LULI data (20 J, 0.5 ps)

RAL data (100J, 0.8 ps)

• Minimum spot size 70 m, cone angle 40°

• Insensitive to pulse energy (to 100 J)

GEKKO laser: 12 green laser beamsE= 10 kJ, t = 1-2 nsec.Uniform irradiation(phase plates) for high density compression.I ~1014 watts/cm2

PW laser: 1 beam (~400 J)At 1 micron.PW peak power is utilized for fast heating.I~1019 watts/cm2

ILE Osaka

Integral FI experiments at Gekko XII-PW have catalyzed FI interest worldwide

Integral experiments at ILE show efficient heating

• Nine drive beams, 2.5 kJ• 1/2 PW ignition beam• Deuterated plastic target

300 J short pulse doubled the core plasma temp to 0.8 keV implying 40% coupling of EPW

250m

X-ray image

Cone Target

104

106

108

0.1 1

Neu

tro

n Y

ield

Heating Laser Power (PW)

c

Rqd timing ~50ps

0

100

200

-200 -100 0 100 200Injection Timing (ps)

0

10

5

a

2.25 2.35 2.45 2.55 2.65

Energy [MeV]

0

1.0

0.5

b

T~0.8 keV

ILE Osaka

A credible pathway to take FI to concept demonstration exists

• Proof of Principle (Concept Extension) Significant core heating at relevant conditions– FIREX1 (Japan)

• Concept Demonstration (Ignition/gain)– US Facilities (, Z, NIF)

with PW

Summary

• Short pulse ( < ~10 psec), high brightness lasers (B > 1015

Watts/cm2-st) have enabled the new field of “high energy density physics (HEDP)”

• There is an increasing national and international interest in HEDP• Fast Ignition exploits the physics and technology of HEDP

& features:– Science frontier-relativistic plasmas, etc– Compatible with all drivers– Flexibility in reactor concepts– International collaborations ?– High gain potential at sub-megajoule energies