ILE, Osaka

Concept of Laser Fusion Power Plant Based on First Ignition

T. Norimatsu 1), Y. Kozaki 2), N. Miyanaga 1), J. Kawanaka 1), H. Azechi 1), H. Furukawa 3),

and K. Tomabechi 4)

1) Institute of Laser Engineering, Osaka University, Suita, Osaka 5650871 Japan.

2) National Institute for Fusion Science, Oroshi, Toki, Gifu, 5095292 Japan3) Institute for Laser Technology, Nishi-ku, Osaka, 5500004, Japan.4) Previous Advisor of Central Research Institute of Electric Power

Industry

ILE, Osaka

Reactor Design Committee was organized to clarify the feasibility of Laser Fusion Plant based

on Fast Ignitionby IFE Forum and ILE, Osaka University

• Chair; A. Tomabechi• Co-chair; Y. Kozaki (IFE, Forum)

T. Norimatsu (ILE, Osaka)

Laser Working Group

N. Miyanaga (ILE),

Y. Suzuki (Laser Front Technol.),

K. Ueda (Univ. Elector-Com.),

N. Tuchiya (Nishin Co.)

Y. Oowadano (AIST),

T. Jitsuno (ILE),

M. Nakatsuka (ILE),

H. Fujita (ILE),

K. Yoshida (Osaka Inst. Technol.),

J. Kawanaka (ILE),

H. Nakano (Kinki Univ.),

Y. Fujimoto (ILE),

H. Kubomura (HP),

T. Kawashima (HP),

S. Matsuoka(HP),

T. Ikegawa(HP),

K. Tusbakimoto (ILE),

J. Nishimae (Mitsubishi Elec.),

H. Furukawa (ILT)

Target Working Group

T. Norimatsu (ILE),

M. Nishikawa (Kyushu Univ.),

T. Konishi (Kyoto Univ.),

T. Endo (Hiroshima Univ.),

H. Yoshida (Gifu Univ.),

M. Nakai (ILE)

Plant system Working Group

Y. Kozaki (ILE),

Y. Soman (Mitsubishi Heavy Ind.),

K. Okano (CRIEPI),

Y. Furukawa (ILT),

Y. Sakawa (Nagoya Univ.),

A. Sagara (NIFS),

T. Norimatsu (ILE)

Purpose1) to make a reliable scenario for the fast

ignition power plant basing on the latest knowledge of elemental technologies,

2) to identify the research goal of the elements

3) to make the critical path clear.

Core plasma Working Group

H. Azechi (ILE),

Y. Nakao (Kyushu Univ.),

H. Sakagami (Hyogo Unv.),

H. Shiraga (ILE),

R. Kodama (ILE),

H., Nagatomo(ILE),

T. Johzaki (ILE)

ILE, Osaka

KOYO-F is a commercial or very “close to” commercial power plant.

レーザー核融合エネルギー開発のロ－ドマップ

炉工学技術開発（ブランケット, 液体金属, トリチウム, 炉材料）, ITER R&D成果

FIREX-I

概念設計 工学設計実験炉(LFER)

繰返工学試験

設計

FIREX-II

建設 運転 I,II 運転 III

2005 2010 2015 2020 2025 2030 2035

実証炉(DEMO)

▲発電実証

実用発電実証 ▲

モジュール 100J 1kJ 10kJ

ターゲット照射技術開発

炉チェンバー技術開発　　液体壁ブランケット開発

炉用レーザー開発(DPSSL)

▲点火燃焼

先進レーザー開発

Load map toward Laser Fusion Energy

Conceptual design Tech. designExperimental Reactor (LFER)

Ignition and burn

Electric power generation

Demo reactor

Electric power to networkHi-rep test

Target injection and tracking

Blanket, heat cycle

Design

LFER

Module development

Laser development Advanced Laser

Reactor technologies for commercial plant (Life time)

Heating to ignition temperature

Laser 200kJ/1HzGain 50Fusion Yield 10MJElectric power 2MW

Laser 1.2MJ/16HzGain 160Fusion Yield 200MJElectric power 1280 MW

ILE, Osaka

What is new?

• Core plasma– Gain estimation and ρR simulation were carried out using

latest simulation codes.• Lasers

– Cooled Yb:YAG ceramic was newly chosen for both compression and heating lasers

• Target– Thermal cavitation technique was employed for fuel loading

in batch process.• Chamber

– Stagnation-free, liquid wall chamber with cascade flow was proposed for the modular reactors.

ILE, Osaka

The detail physics of the Fast Ignition are investigated with computational simulations

Core plasma

Simulation of non-spherical implosion for FIREX-I experiment (by PINOCO-2D)

Generation of high energy electron (by FISCOF2D)

Heating of core plasma by the high energy electrons is simulated (by FIBMET)

0 5 10 15 20102

103

104

105

106

107

1.8 MeV

0.35 MeV

5.0 MeV

Elec

tron

num

ber [

arb.

uni

t]

Electron energy [MeV]

cone

0 1 2 3 4 5 6 70.25

0.30

0.35

0.40

0.45

0.50

T core

[ke

V]Time [ps]

Te Ti

ne,rear= 2nc

ne,rear= 100nc

ne,rear= 10nc

Beam condition

0 1 2 3 4 5 6 70.25

0.30

0.35

0.40

0.45

0.50

T core

[ke

V]Time [ps]

Te Ti

ne,rear= 2nc

ne,rear= 100nc

ne,rear= 10nc

Beam condition

w/ initial perturbation

w/O initial perturbation

Electron spectrum generated by the laser plasma interaction in the cone geometry

Magnetic field in the cone geometry. The hot electrons are transported along cone surface guided by static magnetic and electric field.

CH-DT shell target with gold cone is imploded by GXII laser. Even though, initial perturbation exists on the target surface, high density core plasma is formed.

In this simulation, initial condition of core plasma is determined by the implosion simulation, PINOCO-2D. Boundary condition of Input hot electron is determined by FISCOF2D.Temporal profiles of bulk-electron and ion temperatures averaged over the dense core region (r > 10g/cc) obtained for the three different REB conditions (ne,rear = 2, 10 and 100 nc)

ILE, Osaka

ILE OsakaAlthough dynamics of cone-guided implosion is quite different from conventional spherical one, high ρR for ignition can be achieved

•existence of the cone causesnon-symmetric slip boundaryablated plasma

•implosion velocity

•timing of maximum density•hot spot

•shock hits the surface of the cone

ρR=2.4g/cm2

Core plasma

ILE, Osaka

Actual energy and power of heating laser required for fast ignition after S. Atzeni, (Phy.Plasmas’99)

d

Rrb

Assuming high energy electron range ;ρ d = 0.6 g/cm2

• Eh = 140{ρ/(100g/cc)}-1.85 kJ• Pb = 2.6{ρ/(100g/cc)}-1.0 PW• Ib = 2.4X1019 {ρ/(100g/cc)}0.95 W/cm2

• rb = 60{ρ/(100g/cc)}-0.975 µm EL= 60 - 100 kJ

Core plasma

Fast Ignition Gain Performance

ILE, Osaka

ρ = 300g/cc,

Energy coupling; ηimp = 5% for implosion & ηheat = 30% for core heating

Pulse width of >10 ps would be accepted for the heating laser. This result relaxes requirements for heating laser. We can use transmitting optics.

0 20 40 60 80 100 120 1401E111E121E131E141E151E161E171E18

Fu

sion

pow

er [W

]

Time [ps]

Core heating duration ( τ = 10ps)

High gain

Transition phase to explosive burning

FIREX-I

FIREX-II

0 20 40 60 80 100 120 1401E111E121E131E141E151E161E171E18

Fu

sion

pow

er [W

]

Time [ps]

Fusi

on p

ower

[W]

Time [ps]

Core heating duration ( τ = 10ps)

High gain

Transition phase to explosive burning

FIREX-I

FIREX-IIρR=0.7g/cm2

Eab=3.5kJ

ρR=1.2g/cm2

Eab=18.4kJ

ρR=2.7g/cm2

Eab=18.4kJ

This is a good news. We can use conventional transmitting optics.

Core plasma

ILE, Osaka

Target for KOYO-F

Fuel shell DT(gas) (<0.01mg/cc) 1,500µｍ

DT(Solid) (250mg/cc+10mg/cc Foam) 300µｍGas barrier (CHO, 1.07g/cc) 2 µｍCH foam insulator (250mg/cc) 150 µｍOuter diameter 1,952 µｍMas of fuel 2.57mg

Total Mas of shell 4.45mg

Basic specification Compression laser 1.1 MJ Heating laser 70kJ Gain 165 Fusion yield 200MJ

Cone Material Li17Pb83 Length 11mm Diameter 5.4 mm Mas 520 mg

3.9 mm

15o9 mm

11 mm

5.4 mm3 mm4.0 mm

Plastic coating

Prabolic mirror

Foam insulator Solid DT+Foam

ILE, Osaka

Critical issues toward high gain

• Can we achieve low adiabat α ?– Current experiments α >2.5

Pulse control, target design are the key.

Self-Ignition

High-Gain

Driven-Ignition

ELtot [kJ]G

ain,

Q

α = 3

10 100 10000.1

1

10

100 α = 2

FIREX-1

FIREX-2

Wet wall reactor

Dry wall reactor

Self-Ignition

High-Gain

Driven-Ignition

ELtot [kJ]G

ain,

Q

α = 3

10 100 10000.1

1

10

100 α = 2

FIREX-1

FIREX-2

FIREX-1

FIREX-2

Wet wall reactor

Dry wall reactor

104

106

108

0.1 1

Neu

tron

Yie

ld

Heating Laser Power (PW)

η = 15%

Heating efficiency η = 30%

Ignition Equivalent Laser Intensity

•Can we deposit 20-30% heating laser energy in a 60 µm diameter x 100 µm area?

•Current theory 15-20 % by 1D• 40% by 2D

?

The Answer will be obtained withFIREX projects.

Lasers

ILE, Osaka

Compression and heating lasers based on identical amplifier

architecture

Compression laser

Main pulse Foot pulse

Energy/pulse 1.1 MJ TBD 100 kJ

Wavelength UV (3ω) 343 nm Visible (2ω) 515 nm 1030 nm

Laser material Cooled Yb:YAG ceramic

Efficiency Efficient Sacrifice of efficiency （ Sacrifice of efficiency ）

Heating laser

Band width Narrow bandBroad band

1.6 THzBroad band (rectangular pulse)

~3 nm

Method forbroad band

Arrayed beam with different wavelength

~0.1 nm@1030 nm(0.08 THz@343 nm)

Broad-band OPA pumped by 3ω,

Spectral angular dispersion

Broad-band OPCPA pumped by 2ω

OPA: optical parametric amplifierOPCPA : optical parametric chirped pulse amplifier

ILE, Osaka

Lasers Originally Yb:YAG has high quantum efficiency of 90%. Why Cooled Yb:YAG now ?

Because there are dramatic Improvements in;

1. Wide Tuning Range of Emission Cross Section (Saturation Fluence)

Realize an efficient energy extraction without optics damages

2. 4-Level Laser System

Enough Laser gain even in diode-pump

3. Improved Thermal Characteristics

High average power operation

Room Temperature

Pump

Laser

Re-absorption

Laser Diode・Low Brightness

400~800cm-1

Quasi-3-Level

2F7/2

2F5/2

Low Temperature

No Re-absorption

4-Level

Lasers

ILE, Osaka

Cooled Yb:YAG ceramic is promising as the laser driver material.

Cooled Yb:YAG ceramic

熱ショックパラメーター

R

T (

W/c

m)

飽和パラメーター hν/σ (J/cm2)

1

10

100

0.10.1 1 10 100

望ましい領域

Glass

Yb:S-FAP

熱破壊

Disordered crystal

crystal

Crystal

Nd:CNGG

寄生発振限界

小口径

モジュール

Nd:SiO2

LHG-8

LSG-91H

LHG-10BK-7

Yb:YAG

HAP4

Nd:Y:CaF2

光学破壊限界

Nd:YAG

ceramics

crystal

ceramics

?

Cooling

Artificial control ofemission cross section

Practical use ofceramic technology

2Saturation parameter

Ther

mal

sho

ck p

aram

eter

Parasitic osc. limit Damage threshold

Thermal fracture

Optimal areaSmallmodule

ILE, Osaka

We experimentally confirmed performance of cooled Yb;YAG

-1 0 1Position (mm)

Inte

nsity

Gaussian fit

Horizontal profile

0

2

4

6

8

0 20 40 60 80 100 120 140 160

g 0(c

m-1

)

Crystal Temperature (K)

g0 = 8 cm-1

at 1.3 kW/cm2

CalculationUsing the observed σem and σab

Dope : 25 at.%Thickness: 1 mm

0

2

4

6

8

0

2

4

6

8

0 20 40 60 80 100 120 140 1600 20 40 60 80 100 120 140 160

g 0(c

m-1

)

Crystal Temperature (K)

g0 = 8 cm-1

at 1.3 kW/cm2

g0 = 8 cm-1

at 1.3 kW/cm2

CalculationUsing the observed σem and σab

CalculationUsing the observed σem and σab

Dope : 25 at.%Thickness: 1 mm

10 100

10

100

1000

3 30 3003

30

300

1% single0.7% ceramics

Temperature (K)

Ther

mal

Con

duct

ivity

(W/m

K)

ILE, Osaka

Overall Efficiencyfrom Electricity to Laser

Implosion Laser Heating Laser

Laser Power 17.6 MW(1.1MJ, 16 Hz) 1.6 MW(0.1MJ, 16Hz)

LD Electrical – LD Optical 60%

LD Optical – 1ω 42%

LD Electrical – 1ω 25.2% (= 0.6 x 0.42)

1ω – 3ω 70% -

1ω – 2ω - 80%

OPCPA Eff. - 40%

Pulse Compression Eff. - 80%

Transportation Eff. 90% 90%

Harmonic Generation and Transportation 63% 23%

Electric Input Power 111 MW 27.6 W

Crystal Heating Power 7 MW 0.7MW

Cooler Electric Power 23 MW 2.1 MW

Electric Power Demands 134 MW 30 MW

Total Electric Power 164 MW

Overall Efficiency 12% (13% + 5.4%)

Lasers

ILE, Osaka

Beam arrays of implosion and hearting lasers

Compression laser beam(343 nm)

Absorber

8x8 incoherentarrays

Heating laser beam (1030 nm)

Foot pulse beam(515 nm)

Heating laser beam

80cm×80cm,32 beams

∆λ = 0.1 nm@fundamental(∆ν = 0.08 THz)

(Grating DT = 3 J/cm2)

(DT = 10 J/cm2)

210cm×210cm,21x21 coherent arrays or

9 bundles of 7x7 coherent arrays

Foot pulse beam(515nm)

Lasers

ILE, Osaka

Illustration of main amplifier using active mirror concept

FiberOscillator

Pre-Amplifier(~ kJ, NIR) Main-Amplifier

(~ MJ, NIR)

3rd Harmonics

2nd Harmonics

PulseCompresso

r

compression Laser(1.1MJ, blue, ns)

Heating Laser(0.1MJ, NIR, ps)

OPCPA

PulseStretcher

Mode-lockOscillator

60kJ x 8 beams

ILE, Osaka

Large diameter laser beams will be distributed to 4 modular reactors using

rotating corner cubes.

FiberOscillator

Pre-Amplifier(~ kJ, NIR) Main-Amplifier

(~ MJ, NIR)

3rd Harmonics

2nd Harmonics

PulseCompresso

r

compression Laser(1.1MJ, blue, ns)

Heating Laser(0.1MJ, NIR, ps)

OPCPA

PulseStretcher

Mode-lockOscillator

・コーナーキューブミラー： 　既設激光XII号光路長調整機構に使用 ・ハニカム構造ミラーによる軽量化 　（試作段階完了）

1

3

分配ビーム配置

回転コーナーキューブミラー

回転軸

蹴り出しミラー

入射ビーム

平行度 < 10 µrad（工作精度） 　→　ポインティング精度* < 10 µrad 　　　 （歳差運動の影響無し）

像転送 　→　センタリング精度* < 1cm（回転周期変動= 0.1%）

* : 最終集光系上で

回転速度モニター

42

(3 rpm)

Rotating corner cubeat 4 Hz

Accuracy for pointing < 10 µrad

No influence of axis vibration

Accuracy for centering <0,5 cm

Layout of distributed beams

Input beam

Lasers

ILE, Osaka

Cooling system with 2MW at 200K can be constructed with existing technology.

１５ｍ

２８ｍ

Electric input power 3600+1500kWCooling water 1300m3/h (32-37oC)Cooling power 2MW at 200K

(δT=5K)Efficiency >30%Coolant R507A（High）＋R23(Low)

Image of 600kW, two coolants refrigerator*This image was produced by Maekawa MFG. Co. LTD.

Lasers

ILE, Osaka

After fast ignition, share of lasers in the construction cost became minor.

Required laser energy became ¼ after fast ignition.

Number of LDs became 1/3 after use of Cooled Yb:YAG

Fast ignition KOYO-FCentral ignition KOYO

Chamber

ILE, Osaka

KOYO-F with 32 beams for compression and one heating beam

• Vertically off-set irradiation

• Cascade surface flow with mixing channel

• SiC panels coated with wetable metal

• Tilted first panel to make no stagnation point of ablated vapor

• Compact rotary shutters with 3 synchronized disks

Chamber

ILE, Osaka

The surface flow is mixed with inner cold flow step by step to reduce the

surface temperature.

If the surface flow is a laminar flow, vapor pressure is too high to reach designated pressure of 5-10 Pa.

This concept was experimentally confirmed by Dr. Kunugi.

Chamber

ILE, Osaka

To prevent stagnation of ablated LiPb, front panels were tilted by 30 degree.

Tilted front panels

Cone type ceiling t=0 ms

t=10ms

t=20ms

Position of mass center of ablated vapor

ILE, Osaka

Beam port will be protected using a magnetic field.

• Preliminary numerical simulation indicates that the tip of beam port can be protected from alpha particles.– B=1 T, pulse operation.– Alpha, 6.3×1017 n/m2, τ=0.18 µs

• Electrons are treated as a fluid and alpha particles are treatedas ions.

H. Nakajima and Y. Kajimura, Private communication

3m

Coil

Inner diameter 15cm

Outer diameter 35 cm

200 MJ/.shot

ILE, Osaka

Final optics will be protected with synchronized rotary shutter, magnetic field, and buffer gas.

1 m s2nd shot

3rd shot4th shot

1s1 0 µ s 1 0 0 µ s 10ms 1 0 0ms

2nd shutter 16rps

3rd shutter 4rps

1st shutter 32rps

Target injectionMiss fired target

1st bluster wave from the wall

v=3,000m/s @20,000K

v=150 m/s

Charged particlies from plasma 1 - 2 µ s alpha 0.2 - 0.4 µ s X-rays 10 ns

Blaster waves

1000

1500

2000

Tem

pera

true

of

inne

r sur

face

(K)

Open

Open

Open

2500

500

Gas temperature (Local peak)

Wall surfaceHole on 1st disk

Hole on 2nd disk

Hole on 3rd disk

32 Hz 16 Hz 4Hz

Vapor

６０ｃｍ

B=1T, ２ｍ

0.5m100m/s

Magnetic field for ions

Rotary shutter for neutral gas

Buffer gas for slow neutral vapor

Chamber

ILE, Osaka

Thermal flow of KOYO-F

SGTurbin

500℃

300℃300℃

50MW

210MW70MW

70MW

240MW

80MW

80MW

500℃

F2+F3 (80cm)12.84 ton/s

Average flow 7.8 cm/s

F１ (20cm)8.56 ton/s

Average flow 24.3 cm/s

Flow rate 21.4 ton/s

904MW

Watercycle

Chamber

LiPb cycle

δt=0.5 oC/shot δt=1.3 oC/shot

ILE, Osaka

Residual gases can be evacuated with lead diffusion pumps.

Pb蒸気拡散

ポンプ

トリチウム

回収処理系へ

A'A

10000.00

LiPb 上部ﾌﾞﾗﾝｹｯﾄ 300 ℃

A-A' 断面図

LiPb液体壁チェンバ－概念図 1/100 単位mm

φ6000.00

Fusion output 　 200 MJ / pulse, 800 MW,Pulse rep-rate s 4 Hz Chamber inner radius 　 3.0 m, upper wall distance from burning center 10.0 m Pulse heat load 　　　 max. 32 J / cm2 , upper wall 2.9 J / cm2 average heat load 　　　 max. 128 W / cm2 , upper wall 11.5 W / cm2 Neutron wall load 　　　 max. 5.6 MW / m2, upper wall 0.5 MW / m2

A A’

ドライ

スクロール

ポンプ

6m

Φ 0.55m

粗びきポンプ区画

（ 1 x 1 x 1m）

5m

Pb拡散

ポンプ

Lead diffusion pump

To tritium recovery system

Dry pump

ILE, Osaka

Tritium necessary for one fuel loading system is about 100g

n=20 x 80 (for 13 min at 2 Hz)

12 cm

Air lock

Air lockAir lockCooling zone Freezing zoneLoading zone

Liquid N2

Liquid He

20 K He 100 torr

19 K DT 128 torr

19 K DT 128 torr

10 K DT 1 torr

DT Pump

DT Pump

2nd Tritium barrier

Vacuum vessel

3 hr

Vacuum Pump

TRS IS & Strage

To injector

Laser Not to scale

Tritium inventory76 g as liquid

0.82 g as vapor

4g in 1600 targets

1.2 g/13 min

5mg/s

ILE, Osaka

Tritium in gas phase and LiPb leach their ultimate concentrations in 30 sec 6 hr, respectively.

3 mg/s

5Pa, 0.16g as gas

Gap for tritium recovery

Tritium barrier

2.8〜28 g in LiPb

0.1 ppm〜1ppm

TBR=1.3

30% burning rate

Tritium of 1 kg is necessary as the initial inventory for 1200MWeplant.

Tritium can be recovered as fuel but diffusion through the heat cycle seems most critical.

Chamber

ILE, Osaka

We estimated the ablation process using ACORE. Stopping power in ionized vapor

was calculated.

Atomic Process Code

Ionization Degree, Population, Energy Level

Stopping Power Code EOS Code Emissivity and Opacity Code

Stopping power Ionization DegreePressure, Specifiic heat

Emissivity, Opacity

ACORE (Ablation COde for REactor)

0

4

8

12

Number Density

(cm -3)1014

1018

1022

Temperature (eV)

10

1

0.1

0.01

Z*

Ziegler’s model

−dEdx

= ni Inll∑

n∑ Pnl π

Z0 e2

Inl

⎛

⎝ ⎜ ⎞

⎠ ⎟

2

Gv

vnl

⎛ ⎝ ⎜

⎞ ⎠ ⎟

102

103

104

105

106

0 0.5 1 1.5 2 2.5 3 3.5

ni = nl , Te = 2024 K

liquid

Ref.

present- dE

/ d

x (M

eV/c

m)

E (MeV)

Present model

G V( ) =α 3/2

V 2 α +23

1 + β( )ln 2.7 + V( )⎡ ⎣ ⎢

⎤ ⎦ ⎥

4 2 20

02 2

4 4e e

e e e

e Z n n edE hKdx m v n v m

π π⎛ ⎞− = ⎜ ⎟⎜ ⎟

⎝ ⎠

Ziegler

Corrected Bethe

Ionization rate of Pb

Chamber

ILE, Osaka

Density, Temperature and velocity profile of ablated material.

1020

1021

1022

1023

-200

0

200

400

600

800

1000

-0.2 0 0.2 0.4 0.6 0.8 1 1.2

Time = 1932 ns

Number Density

Velocity

Num

ber

Den

sity

(cm

-3)

Velocity (m

/s)

x (mm)500

1000

1500

2000

2500

3000

3500

4000

4500

-0.2 0 0.2 0.4 0.6 0.8 1 1.2

R = 3 m

595.5 ns

1932 nsT

empe

ratu

re (K

)

x (mm)

102

103

104

105

106

107

108

109

0.0 0.5 1.0 1.5 2.0

alfaalfa (debri)deuteriumtritiumprotonherium3

Inte

nsit

y (W

/cm

2 )

Time (µs)

1020

1021

1022

1023

-0.2 0 0.2 0.4 0.6 0.8 1 1.2

R = 3 m

595.5 ns

1932 ns

Num

ber

Den

sity

(cm

-3)

x (mm)

Chamber

ILE, Osaka

Lot of 0.1 µm radius clusters are formed after adiabatic expansion.

(Luk’yanchuk, Zeldovich-Raizer Model)

20% of ablated vapor becomes aerosol.

Chamber

ILE, Osaka

Beam ports and ceiling will be made with porous metal and followed by condensation of vapor ablated by previous shot.

80%

20%

Diameter 0.1µｍ

Liquidmembrane

aerosol

Vapor ～1000m/s

Condensation rates of the fast and slow component at the first bounce are about 60% and 100%, respectively.

These rates are sufficient to keep the vapor pressure < 5 Pa and to form a 2 µm-hick, protective layer before the next laser shot.

0 2000 4000 6000 8000 1 1040

Ti

Pb

蒸気温度（Ｋ）

吸着係数

Con

dens

atio

n co

effic

ient

on

col

d su

rfac

e

Vapor temperature (K)

1

Aerosol mainly appears in slow component. Now secondary particles because the surface energy > kinetic energy

ILE, Osaka

Critical issue in chamber

• Probability for direct exposure of the same place <1/103 – 1/104

– If we assume maintenance period of 2 years and acceptable erosion of 3mm, the probability for direct exposure of the same place with α particles must be less than 1/104.

– The answer would be improve flow control, material selection, and chamber radius

• Although tilted front panels will reduce the stagnation to 1/103, few gram of LiPb vapor will stagnate at the center.– Off set irradiation would be the answer.

Dry surfaceLiquid LiPb

ILE, Osaka

Summary 1

– 1) We have examined the design windows and the issues of the fast ignition laser fusion power plants. ~1200 MWe modular power plants driven at ~16 Hz

– 2) For laser driver we have considered the DPSSL design using the Yb:YAG ceramic operating at low temperature (~200K).

– 3) We have proposed the free fall cascade liquid chamber for cooling surface quickly enough to several Hz pulses operation by short flow path. The chamber ceiling and laser beam port are protected from the thermal load by keeping the surface colder to enhance condensation of LiPb vapor.

– 4)For exhausting DT gas mixed with LiPb vapor we have designed diffusion pumps using Pb (or LiPb) vapor with effective exhaust velocity about 8 m3/s DT gas.

ILE, Osaka

Summary 2

• Core plasma, – High density compression of cone target– Heating efficiency of 30% – Adiabat a <2.5

• In the laser system– Construction of laser itself seems possible with existing

technology.– Beam steering of ignition beam may be critical.

• Chamber system– Chamber clearance– Tritium confinement

ILE, Osaka

Basic specification of KOYO-F

Net electric output 1283 MWe (320 MWe x 4)

Electric output from one module 320 MWe

Target gain 167

Fusion Yield 200 MJ

Laser energy/Beam number 1.2 MJ（Compression=1.1MJ/32beams, Heating=100kJ 1beam）

Laser material／Rep-rate Cooled Yb:YAG ceramics at 150～220K /16 Hz

Chamber structure/Rep-rate at module Cascade-type, free-fall liquid LiPb wall/4 Hz

Fusion power from a module 800 MWth

Blanket gain 1.2（design goal）

Total thermal output from a module 916 MWth

Total thermal output from a plant 3664 MWth (916 MWth x 4 )

Heat-electricity conversion efficiency 41.5 %（LiPb Temperature 500℃)

Gross electric output 1519 MWe

Laser efficiencies13.1% (compression), 5.4% (heating)、Total 11.8%（including cooling power)

Recirculating power for laser 164 MWe（1.2 MJ x 16 Hz / 0.118)

Net electric output/efficiency 1283 MWe(1519 MWe - 164 MWe - 72 MWe Aux.)/32.7%

ILE, Osaka

Plant size is 303mlong x 110mwidth x 50mhigh.