A Multi-Kilojoule, Multi-Petawatt Heating Laser for Fast ... · LFEX-Laser A Multi-Kilojoule, Multi-Petawatt Heating Laser for Fast Ignition J. Kawanaka, N. Morio, S. Matsuo, K. Kawabata,

LFEX-Laser A Multi-Kilojoule, Multi-Petawatt Heating Laser

for Fast Ignition

J. Kawanaka, N. Morio, S. Matsuo, K. Kawabata, Y. Kawakami, Y. Fujimura, K. Sawai, K. Tsuji, Y. Suzuki, Y. Matsuda, T. Kawasaki, H. Murakami, M. Ishida, H. Kitamura,

H. Matsuo, T. Sakamoto, T. Sezaki, T. Yanagida, S. Tokita, Y. Nakada, K. Tsubakimoto, S. Fujioka, H. Shiraga, T. Jitsuno, and N. Miyanaga,

and Plasma Exp. Group

Institute of Laser Engineering, Osaka University

26th IAEA Fusion Energy Conference - IAEA CN-234 Kyoto, Japan

1. A view of the whole LFEX system

2. Key technologies of LFEX

2-1 Large aperture dielectric grating for kJ, ps

pulses in a pulse compressor

2-2 Deformable Mirror for wavefront compensation

2-3 Novel pulse cleaner for high intensity contrast

3. Summary

Outline

Implosion by

multiple beams

Fast heating by

Intense laser

Ignition and burn

Fast ignition in laser fusion

Gekko XII LFEX

LFEX Spec.

LFEX spec.

Wavelength: 1053 nm (Nd: glass laser)

Pulse energy: 10 kJ

Pulse width: 1-20 ps (FWHM) 10 ps (typical)

Peak Power: 0.5~10PW (10 kJ/1 ps, 5 kJ/0.5 ps for

ultra high-field science)

Pulse shape: trapezoid with <2 ps rise time

Focal spot: 20-30 µm (≥50 % encircled energy)

For >5-keV heating of dense fuel,

ps-Laser 4 beams

10 kJ 1~20 ps

0.5~10 PW

ns-Laser 12 beams 6 kJ (2w)

2.4 kJ (3w) 1~10 ns

0

1

2

3

4

5

1 10 100 1000 10000 100000

PW lasers in the world

Pulse Energy (J)

5 4 3 2 1 0

Pe

ak P

ow

er

(PW

)

1 10 102 103 104 105

Astra-Gemini

IOP CAS

J-KAREN

SIOM

GIST

Ti:sapphire

TX-PW OMEGA-EP

Vulcan Orion Z-Petawatt

(Nova)

Nd:glass

20 fs 1 ps

0

1

2

3

4

5

1 10 100 1000 10000 100000 1000000 10000000

Pe

ak P

ow

er

(PW

)

Pulse Energy (J)

How can we generate PW peak power?

300 fs

Chirp Pulse Amplification (CPA)

Chirped

Main Pulse

AOPF

Osc. Amplifier

Osc. Amplifier Pulse

Strecher Pulse

Compressor

Dt ~ x 103 ~ 105

High electric field of a laser damages optics, which are used in the amp.

PW with kJ

Seed pulse

Block diagram of the LFEX system

Main Amplifier

3-stage OPCPAs

ML Fiber Osc.

Pulse Stretcher

Spatial Light Modulator

4-pass Rod Amp. Double Rod Amps

Image Relay

Compressor Beam Divider

Target Chamber

Main Amplifier

High power shots are available now!!

1) Monochromatic (ns) > 3 kJ / beam

2) Chirped pulse (ns before compression)

~ 3 kJ / beam

3) Compressed pulse (ps) 2 kJ (4 beams)

1 ps（shortest）

2 PW（Maximum）

For >5-keV heating of dense fuel,

LFEX spec.

Wavelength : 1053 nm

Pulse energy : 10 kJ

Pulse width : 1-20 ps

Peak Power : 0.5~10PW

Pulse Intensity : >1020 W/cm2

(on target)

Pulse Contrast : <10-11

Focal spot : 20-30 µm

~ 40 mJ

~ 10 J

~ 10 J/beam

~ 3 kJ/beam

~ 2.5 kJ/beam 1 ps X 4 100 fs, 1 nJ

2.5 ns

Key Technologies

Main Amplifier

3-stage OPCPAs

ML Fiber Osc.

Pulse Stretcher

Spatial Light Modulator

4-pass Rod Amp. Double Rod Amps

Image Relay

Compressor Beam Divider

Target Chamber

Main Amplifier

High power shots are available now!!

1) Monochromatic (ns) > 3 kJ / beam

2) Chirped pulse (ns before compression)

~ 3 kJ / beam

3) Compressed pulse (ps) 2 kJ (4 beams)

1 ps（shortest）

2 PW（Maximum）

Large-aperture Deformable Mirror

Novel Pulse Cleaner

Large-aperture Dielectric Grating

Key Technologies

Main Amplifier

3-stage OPCPAs

ML Fiber Osc.

Pulse Stretcher

Spatial Light Modulator

4-pass Rod Amp. Double Rod Amps

Image Relay

Compressor Beam Divider

Target Chamber

Main Amplifier

High power shots are available now!!

1) Monochromatic (ns) > 3 kJ / beam

2) Chirped pulse (ns before compression)

~ 3 kJ / beam

3) Compressed pulse (ps) 2 kJ (4 beams)

1 ps（shortest）

2 PW（Maximum）

Large-aperture Deformable Mirror

Novel Pulse Cleaner

Large-aperture Dielectric Grating

Diamond compressor

Main Amplifier

High power shots are available now!!

1) Monochromatic (ns) > 3 kJ / beam

2) Chirped pulse (ns before compression)

~ 3 kJ / beam

3) Compressed pulse (ps) 2 kJ (4 beams)

1 ps（shortest）

2 PW（Maximum）

Gratings 2

Gratings 1

Mirror

Mirror

Mirror

Mirror

~ 1 ps ns

E = 2.5 kJ/beam

Uth ~ 0.2 J/cm2 (Au)

2 J/cm2 (Dielectric)

S = 5000 cm2 1250 cm2

Meter size

Dielectric Gratings Damage threshold Minimum cross section

Pulse energy

All large aperture dielectric gratings are fully installed.

92 cm × 42 cm, 1740 grooves/mm

R

+Z

+X

-Z

-X X

Z 42 cm

1740 grooves/mm

92 cm

The world’s largest dielectric gratings

Difficulties ・ Dielectric coating on large aperture silica glass ・ Extremely precise grooving (0.05ppm)

Grating blank

92 cm 42 cm

Ion Etching

Scanning Exposure (1.3-m stage)

Resist coating

Dielectirc coating

Polishing

Quartz material (Tosoh Co.)

ILE, Osaka Univ.

Japan

U.S.

Ion source

Melting pot

Wavefront Inspection

Cleaning

Wavefront Inspection

PGL, Massachusetts

Okamoto Optics Works (Yokohama)

2m-size Coating machine

Development & manufacturing system of large-aperture, high perfomance dielectric gratins

The Observed Typical Characteristics

+20%

-20%

The pulse energy is limited below 500 J/beam because of optical damage of mirrors. ↓

2 kJ with 4 beams

Am

plif

ied E

ne

rgy (

J)

Input pulse energy after OPCPA (mJ)

0

100

200

300

400

0

500

100 200 300 500 600 700 400

Pulse energy

H1 SSA

ShotNo.2126 ShotNo.2127

Rod Shot Disk Shot

H1 SSA

ShotNo.2126 ShotNo.2127

Rod Shot Disk Shot

Disk

Rod

Pulse width (Single Shot Auto-Collirator)

1 ps

2kJ, 1 ps, 2 PW

LFEX is the highest peak-power laser in kilojoule

Pulse Energy (J)

LFEX 2 PW 2 kJ 1 ps

5 4 3 2 1 0

Pe

ak P

ow

er

(PW

)

1 10 102 103 104 105

Astra-Gemini

IOP CAS

J-KAREN

SIOM

GIST

Ti:sapphire

TX-PW OMEGA-EP

Vulcan Orion Z-Petawatt

(Nova)

Nd:glass

20 fs 1 ps

The world’s highest peak power in kilo-joule

Key Technologies

Main Amplifier

3-stage OPCPAs

ML Fiber Osc.

Pulse Stretcher

Spatial Light Modulator

4-pass Rod Amp. Double Rod Amps

Image Relay

Compressor Beam Divider

Target Chamber

Main Amplifier

High power shots are available now!!

1) Monochromatic (ns) > 3 kJ / beam

2) Chirped pulse (ns before compression)

~ 3 kJ / beam

3) Compressed pulse (ps) 2 kJ (4 beams)

1 ps（shortest）

2 PW（Maximum） Pulse compressor with large aperture dielectric gratings

Deformable Mirror

Pulse Cleaner

Wavefront compensation with Deformable Mirror

Main Amplifier

High power shots are available now!!

1) Monochromatic (ns) > 3 kJ / beam

2) Chirped pulse (ns before compression)

~ 3 kJ / beam

3) Compressed pulse (ps) 2 kJ (4 beams)

1 ps（shortest）

2 PW（Maximum）

Normal Mirror

Distorted Wavefront

Defomable Mirror (DFM)

Distorted Wavefront

DFM Mirror

Wavefront Compensation!!

Major cause of

phase aberration

0.54µm rms

FFP

Wavefront w/o DFM

Shack-Hartmann

Active pre-compensation with large-aperture DFM

Main Amplifier Image Relay

DFM75 DFM125

H1H-FFP

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

Energ

y  I

n  A

pert

ure

 (％

)

1514131211109876543210

Diffraction  Limitt  (2.44Fλ)

H1_ROD H1_DA

Rod

DA

46% @ 5Fl

FFP

Shack-Hartmann

Wavefront

FFP

w. DFM

0.11µm rms

High focusability 5% @5Fl 35% @5Fl

Key Technologies

Main Amplifier

3-stage OPCPAs

ML Fiber Osc.

Pulse Stretcher

Spatial Light Modulator

4-pass Rod Amp. Double Rod Amps

Image Relay

Compressor Beam Divider

Target Chamber

Main Amplifier

High power shots are available now!!

1) Monochromatic (ns) > 3 kJ / beam

2) Chirped pulse (ns before compression)

~ 3 kJ / beam

3) Compressed pulse (ps) 2 kJ (4 beams)

1 ps（shortest）

2 PW（Maximum） Pulse compressor with large aperture dielectric gratings

Deformable Mirror

Pulse cleaner

Main Pulse

AOPF (Amplified Optical

Parametric

Fluorescence)

Pulse intensity contrast

Pulse Intensity (on target) : >1020 W/cm2

Laser intensity to generate plasma : ~109 W/cm2

Required Intensity Contrast : <10-11

Pre-Plasma Production

Imain

IAOPF Intensity Contrast = Imain

IAOPF

Target

SA (Cr4+:YAG)

Pulse Compression

CPA

General

Main Pulse

AOPF

Chirped Main Pulse

AOPF

Residual AOPF

Compressed

Main Pulse

Pre-Plasma Production

Saturable absorber as pulse cleaner

Cr4+:YAGTransmission

GratingTransmission

Grating

Main Pulse

AOPF

Lens

Original Spectrally Resolved Pulse Cleaner

4-f non-dispersive optical layout

f f f f

Saturable Absorber

(Cr4+:YAG) Transmission

Grating Transmission

Grating

Lens Lens

Chirped

Main Pulse AOPF

2~3 ns

~20 ps

AOPF is reduced

-300 -200 -100 0 100

1 10-1

10-2

10-3

10-4

10-5

10-6

10-7

10-8

10-9

10-10

10-11

Time (ps)

Inte

nsity (

arb

. u

nit)

w/o SA

with SA

10 ps

50 ps

170 ps

Pulse intensity contrast after OPCPA

1 x 10-10 Third autocorrelator Mesurement Limit

High contrast is successfully achieved for plasma experiments.

Key technologies

・ Large aperture dielectric gratings has been developed for kJ, ps pulse

compressor.

・ Large aperture deformable mirrors has been successfully pre-compensated

the wavefront distortion to improve focusability.

・ Our original pulse cleaner improved the intensity contrast.

As a result,

The world’s highest peak-power laser in kilojoule, LFEX has been

successfully demonstrated.

1. Pulse energy : < 500J / beam (due to mirror damage after compression)

2. Pulse duration: 1~2ps (observed with single-shot auto-correlator)

3. Peak Power : ~ 2 PW

4. Pulse contrast : <10-10 (@ -170ps by using our new pulse cleaners)

In future,

Pulse energy will be increased for fast ignition demonstration by improving filling factor and so on,.

Summary

0

1

2

3

4

5

1 10 100 1000 10000 100000 1000000 10000000

Pe

ak P

ow

er

(PW

)

Pulse Energy (J)

Stretcher and Compressor

300 fs

Chirped

Main Pulse

AOPF

Lens Lens Grating Grating

Grating

Grating Grating

Compressor

Stretcher

Mirror fs ~ ps ns

fs ~ ps ns

Large aperture grating with high optical strength is necessary to kJ pulse energy.

Output from amplifier

2x2

1x4

2x2

Beam transport

Pulse compressor

Focusin Optic

Sensor - 3

Sensor - 1

GXII Target Chamber

105cm×85cm

・途中大幅設計変更

・LLNLとの共同研究

連携企業：三菱電機通信機製作所

Pulse compressor and focusing optics

Interaction

chamber

SM1

SM2

M2

M7

M7

M6

M4

M3

M9

M-10

M1

Grating 2

Grating 1

Monitor 1

Monitor 3 Off axis

parabola mirror

M5

SiO2 HfO2 SiO2 HfO2

0.575 µm

with

PC

&

PM

w/o

PC

&

PM

@ -2.8 ns

100 μm/div

＠ -140 ps ＠ +1.6 ns @ -2.0 ns

100 μm/div 100 μm/div 100 μm/div

@ -1.3 ns

27

Irradiation to metal target with high energy pulses

S. Fujioka, Y. Arikawa, S. Kojima et al., Physics of Plasmas, 23, 0565308 (2016).

No pre-plasma at 140ps before the main pulse

2013

before

cool REB

2014

after

cool REB

Arikawa et al.,

28

Electron temperature in plasma

w/o pulse cleaners

Reducing electron tempearture

w pulse cleaners

1018

1019

1020

1021

10

100

Experiments

Weak focusing,

High contrast

tL= 1.5 ps

tL= 3 ps

tL= 6 ps

Tight focusing,

Low contrast

tL= 1 ps

M

axim

um

Pro

ton

En

erg

y [

Me

V]

Laser Intensity [Wcm-2]

50Adiabatic model

with 3D effect

for tL = 1 ps

29

Low-contrast pulse Small focal spot VULCAN-PW, 400J, 1ps, Nat. Phys. 3, 58 (2007)

The results were well scaled by TNSA model involving adiabatic cooling and 3D effect that weaken the ion energy.

Scaling of proton energy with PW laser Our experimental results are higher than the prediction of TNSA model.

Proton energy increases with the pulse duration on a fixed intensity.

High-contrast pulse Large focal spot LFEX (present)

Target : Al, 5 mmt

Y. Arikawa, A. Morace, A. Yogo, X. Vaisseau, Y. Abe, S. Kojima, S. Sakata, H. Lee, T. Hosoda, K. Law, K. Matsuo, T. Gawa, S. Tosaki, Y. Fujimoto, T. Jitsuno, Y. Hironaka, K. Mima, M. Murakami, N. Miyanaga, H. Nagatomo, M. Nakai, Y. Nakata, K. Nishihara, H. Nishimura, T. Norimatsu, T. Sano, Y. Sakawa, K. Shigemori, K. Tsubakimoto, H. Shiraga, H. Azechi Institute of Laser Engineering, Osaka University, Japan A. Sunahara Institute for Laser Technology, Japan T. Johzaki Hiroshima University, Japan K. Kondo Tokyo Inst. Tech., Japan A. Iwamoto, T. Ozaki, T. Watanabe, H. Sakagami National Institute for Fusion Science, Japan T. Shirato, N. Ohnishi Tohoku Univ., Japan H. Sawada, Y. Sentoku University of Nevada, Reno, USA Z. Zhang Institute of Physics, China J. Santos, M. Bailly-Grandvaux, D. Batani, R. Bouillaud, P. Forestier-Colleoni, S. Hulin, Ph. Nicolaï, V. Tikhonchuk CELIA, Univ. Bordeaux, France L. Giuffrida ELI-Beamline Project, Institute of Physics, Czech Republic J.L. Dubois, J. Gazave, D. Raffestin and J. Ribolzi. CEA, France M. Chevrot, S. Dorard, E. Loyez, J.R. Marques, F. Serres LULI, Ecole Polytechnique, France J. Honrubia Universidad Politécnica de Madrid, Spain 3

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