ILE OsakaActivities on reactor designfor fast ignition

T. Norimatsu, H. Azechi, Y. Kozaki, Y. Fujimoto, T. Jitsuno, T. Kanabe, R. Kodama, K. Kondo, N. Miyanaga, H. Nagatomo, M. Nakatsuka, H. Shiraga, K. A.

Tanaka, K. Tsubakimoto, M. Yamanaka, R. Yasuhara, and Y. Izawa,

Institute of Laser Engineering, Osaka University, 2-6, Yamada-oka, Suita, Osaka 565-0871, Japan, E-mail; norimats@ile.osaka-u.ac.jp

Presented at Japan-US workshop on Laser IFE

March 21-23, 2005, GA. San Diego, USA

ILE Osaka

Outline• Introduction

– IFE plant Design Committee– Roadmap

• Chamber concept– KOYO-F with a wet wall

• Protection scheme for the final optics

• Scenario for fuel loading and injection

• Summary

ILE Osaka

IFE plant design committee was organized under collaboration of ILE, Osaka and IFE Forum.

• Chairman: K. Tomabechi Blue; from companyVice chairman: Y. Kozaki, T. Norimatsu Black; form university

• Supervisor groupK. Ueda, M. Nishikwam K. Okano, T. Yamanaka, A. Nosaka, Y. Ogawa, H. Kan, A. Koyama, T. Konishi, N. Tanaka, A. Sagara, Y. Hirooka, H. Nakazato, Y. Soman, H. Azechil K. Mima, S. Mori, Y. Nakao, N. Miyanaga, M. Nishikawa, K. Tanaka

• Plasma working groupH. Azechi, H. Shiraga, K. Mima, R. Kodama, Y. Nakao, H. Nagatomo, S. Ishiguro, T. Jozaki

• Laser working groupN. Miyanaga, Y. Suzuki, Y. Owadano, T. Jitsuno, M. Nakatsuka, H. Fujita, K. Yoshida, H. Nakano, T. Kanabe, H. Kubomura, Y. Fujimoto, T. Tsubakimoto, T. Kawashima, H. Furukawa, J. Nishimae

• Target working groupT. Norimatsu, A. Iwamoto, M. Nishikawa, M. Nakai, H. Yoshida, T. Endo

• System working groupY. Kozaki, K. Okano, A. Sagara, Kunugi, T. Konishi, H. Furukawa, M. Nishikawa, Y. Sakawa, Y. Ueda, K. Hayashi, Y. Soman, M. Nakai

ILE Osaka

Fast ignition can reduce the required laser energy because of the smaller PV work.

rhρh < ρc/4

rcrc

rh < rc/4ρh ~ ρc

Fast heating needs petawatt laser.Critical issue is energy coupling.

Central ignition Fuel capsule is compressed with 4MJ laser to nucleate a hot core for self ignition.

Compression Ignition Burn

Heating laser 1-10 ps pulse length 50 - 100 kJ

Compression laser 10 ns pulse length 50-500 kJ

Fast ignition Fuel capsule is compressed with 0.5 MJ laser to a high density and ignited by a PW laser.

Gain for commercial reactor

US NIF

KOYO

0.01 0.1 1 10Laser Energy (MJ)

1

10

100

Fusi

on G

ain

Fast ignirionCentral ignition

KOYO-F (solid wall)

KOYO-F (liquid wall)

ILE Osaka

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

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

d

Rrb

EL= 60 - 100 kJ

40 60 80 1000

50

100

150

Targ

et G

ain

Driver Energy for Core Heating,Edh[kJ]

Pure DT10mg/cc Foam

30mg/cc Foam

ILE Osaka

Roadmap toward laser fusion power plant by fast ignition

Road map of Fueling

FIREX (Fast Ignition Realization Experiment)

2005 2010 2015 2020 2025 2030

Conceptual design Design LFER Laser Fusion Experiment ReactorHigh Repetition

Test Facility

DEMO Power PlantDesign

Cryogenic Technology

Foam method

Controlled beta layering

Mass production

Elemental technology Shell, Cone, Assembling

Fuel loading

Injection

Pneumatic method

Coil gun method

Full injection system Continuou mode

DesignOff site

Target Factory

DesignOn site

Fueling system

Tracking

Optical phase conjugationmethod

Optical Correlator method

System integration

Multi injection system Burst mode

ILE Osaka

Outline• Introduction

– Reactor Design Committee– Roadmap

• Chamber concept– KOYO-F with a wet wall

• Protection scheme for the final optics

• Scenario for fuel loading and injection

• Summary

ILE Osaka

Basic specification of KOYO-F with liquid wall

• Plant with 5 modular reactors– Electric output power 1200 MW

(250MW for laser)• Laser 1100kJ+100kJ

Rep-rate 4 Hz x 4Operation power 250 MW

• Target gain 160Blanket gain 1.15Thermal output power 770 MW/reactor

• Conversion efficiency 40 %

ILE Osaka

Wet wall reactor for fast ignition scheme

• KOYO-F has 1.1 MJ, 32 beams for compression, 100kJ heating laser and two target injectors.

• Thermal out put 200 MJ/shot

Rep-rate 4 Hz

• KOYO-F has vertically off-centered irradiation geometry to simplify the protection of ceiling.

ILE Osaka

Layout of heating laser makes new issue.

30 compression beams + heating laser 32 compression beams + heating laser

(0,0,0)

(1,0,0)

In the case of (0,0,0) layout, 80 % energy of neighboring 3 beams irradiates the cone.Power control is necessary.

ILE Osaka

In the previous cascade reactor, chamber clearance would be the critical issue.

Ten kg of LiPb will evaporate by a microexplosin. Top-open geometry will form an upwardflow, which would make the clearance time longer.

ILE Osaka

The first wall is pours metal plates that are saturated with liquid LiPb and are tilted to make a down flow after collisions at the center.

Average gas pressure assuming pure laminar flowY. Kozaki et al., IAEA, FEC

Mixing of surface flow is necessary to reduce the vapor pressure before the next laser irradiation.

ILE Osaka

To keep the surface wet,pours metal will be used.

• Pours metal allows penetration of Liquid LiPb, resulting the surface is always kept wet.

This scheme can save the electric power to circulate the heavy liquid LiPb.1MW for the surface flow0.3 MW for blanket.

Ferrite

1m

0.1m

400oC0.8m3/s

400oC2.1m3/s

500oC550oC

Vav=0.4m/s

Vav=0.1m/s

δt=1.3 oC/shot

1 m

Graphite

1 m

LiPb Blanket

0.2 m

Gass buffer to prevent "water hammer" Porous metal

Average flow rate0.1 m/s

0.2 m/s

δt=0.5 oC/shot

ILE Osaka

Concept of cooling system

For laser and utilities250MWe

For 1st wall

Electric power1450MWeT -> E 41�

Electric output1200MWeTurbin

eGenerator

Steam generator

Blanket

400�

400�

550�

500�

Blanket

Liquid wall

Reactor

4 reactors

(LiPb)

(LiPb)

(LiPb)

(LiPb)

3.1×10�kg/h (0.83m�/s)

8.38×10�kg/h (2.22m�/s)Fusion yield (with blanket)

770MWt (870MWt)

,750MWt

,150MWt

By SohmanJNC

ILE Osaka

Outline• Introduction

– Reactor Design Committee

• Chamber concept– KOYO-F with a wet wall

• Protection scheme for the final optics

• Scenario for fuel loading and injection

• Summary

ILE Osaka

Motion of ablated plume

1 016

1 017

1 018

1 019

1 020

1 021

1 022

1 023

1 03

1 04

1 05

N u m b e r D en sity

T e m p e r a tur e

(b)

Tem

peratu

re (Kelvin

)

Nu

mb

er D

ensi

ty (

cm-3) Time = 2982.1 ns

0 0.2 0.4 0.8 1.00.6x (mm ) 10 20

10 21

10 22

10 23

10 3

10 4

10 5

0 0.2 0.4 0.6 0.8 1

Nu

mb

er D

ensi

ty (

cm-3) T

emperatu

re (Kelvin

)

x (mm)

Temperature

Number Density

140m/s

Simulation resultInitial condition for analytical model

Reference H. Furukawa, Y. Kozaki, K. Yamamoto, T. Johzaki, and Kunioki Mima,

‘Simulation on Interactions of X-Ray and Charged Particles with First Wall for IFE Reactor ‘

Submitted to Fusion Engineering and Design (2004).P 1

ILE Osaka

Saturation and Quenching of Pb plumein spherical isothermal expansion

rq t( ) / R t( ) = 1− tk Ψ t( )dΨ t( ) / dt( )1/2

rc t( ) / R t( ) = 1− Tc / T0( )Ψ t( )

10-1

100

101

102

10-1 100 101 102

Time ( µs)

u 0 = 3x10 4 cm / s

Plume Boundary

Quenching Wave

Saturation Wave

r (t

) / R

0

10-1

100

101

102

10-1 100 101 102

u 0 = 10 5 cm / s

r (t

) / R

0

Time ( µs)

Quenching Wave

Saturation Wave

Plume Boundary

A saturation wave , and a quenching wave propagate from outside to the center.When the saturation wave passed by, condensation starts. (The temperature decreases.)

When the quenching wave passed by, condensation ends. ( The density is too low)

P 4

ILE Osaka

Protection scheme of final optics by synchronized rotary shutters

0.05Torr Xe or D2

The rotational speed of the 1st disk is~1000 rpm.

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Simulation of liquid wall reactor started.

LiPb in 2004

ILE Osaka

No deposition of LiPb was observed on witness plate in 0.1 Torr H2.

0

20

40

60

80

100

0 200 400 600 800 1000 1200

No increase in absorption was obserbed.

Glass substrateTopBottom

Tran

smitt

ance

(%)

Wavelength (nm)

Pb deposition area

It seems that Pb vapor condenses on cold surface before forming aerosol.

3 cm

50 cm

1400K

800K

300K

500K

Pb vapor rich

H2

ILE Osaka

Pb vapor whose initial speed of 100 m/s can not reach final optics in 0.1 Torr buffer gas.

0.5m100m/s

Pb get into the duct at the rage of 5 mg/shot.-> 473 kg/year !! Cleaning is necessary.

ILE Osaka

If evaporated vapors collide at the center and lose the momentum, the rep-rate would be limited.

Compression beams

Fire position

Chamber center

Aerozol

Top view

Target injectorOffset irradiation would be the solution.

In the case of LFE reactor, the fire position is not necessary at the chamber center.

ILE Osaka

Outline• Introduction

– Reactor Design Committee

• Chamber concept– KOYO-F with a wet wall

• Protection scheme for the final optics

• Scenario for fuel loading and injection

• Summary

ILE Osaka

Two or three injector will be used because it seems difficult to load fragile foam targets

into the sabots at 4 Hz

0 m10 m20 m30 m

1st 2nd

Pneumatic gun Coil gun

Differential pump zone

Sabot decelerator

Detection Differential pump Sabot collect

Fuel, Sabot loading zone Rotary shutter

10 m

2 Hz x 2 = 4Hz�@‚ ‚é ‚¢ ‚Í 3Šî ‚É‘�‚â ‚µ �A1‘ä ‚Í ŒÌ�᎞—p‚Ì ƒI ƒvƒVƒ‡ƒ“‚à

• Pneumatic acceleration with 80K He and fine adjustment by coils

• V=300+/-1m/s 2 Hz operation

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Model target

• Foam insulated Solid DT with LiPb cone whose inner surface is parabolic

• ShellOuter insulator 250mg/cc

200µmGas barrier 2µmSolid DT 200µm

• ConeLiPb 0.5�

Issue; Fabrication of cone with LiPbHow to fill the fuel in short time?

3.46 mm

5 mm

8.5 mm5

mm

3.5 mm

15o

1.06 mm

24.5oFor Reactor

ILE Osaka

Thermal cavitation technique is the solution for fuel loading in batch process.

Vent holeFeeder hole

• Thermal cavitation method can fill liquid fuel into foam layer without feed-back control.

• Required condition is;

Diameter of foam shell��Vent port�Feeder port��Cell size of foam

ILE Osaka

Demonstration of thermal cavitation with hemi foam shell

• Liquid D2 was evacuated by a heater outside the pot.

ƒq�[ƒ^�[

CCDƒJƒ�ƒ‰

‰t‘Ì �d�…‘f

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Step 1 Saturation of foam with liquid DT

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Step 2 Evacuation by laser heating

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Step 3 Finish

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Extra fuel (5.4%) will be loaded due to the meniscus formed between cone and shell.

• Liquid fuel in outer meniscus will move to inside after stopping the laser irradiation.

• There is another extra liquid in the meniscus formed between the cone and inner surface of the foam layer.

• These extra fuel will compensate the shrinkage of hydrogen during freexing(15%)..

ILE Osaka

Fuel loading system by thermal cavitation method.

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 inventory100g

ILE Osaka

When gun length is 10 m, residual gas pressure at the next injection is estimated to be 0.03 atm, which may disturb

cryogenic layer.

For simplification, the gas is initially stationary and pumping starts at both ends at t=0.

Pevac pressure in tube at the next injection

tevac time needs for evacuation Our estimation indicated that the pressure of residual gas at the next injection is 0.03 atm.

Thermal load for cryogenic target?

Needs differential pumping system

This work is supported by Dr. T. Endo of Hiroshima Univ..

ILE Osaka

To vacuum

Radiation shield

To vacuum

Differential pumping

To vacuum

Room Temp. Atmospheric pressure

Cryogenic Temp. Vacuum

To vacuum

To vacuumTo vacuum

To coil gun

Concept of sabot / target loader

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‚P‚O‚j

‰t‘Ì ’‚ ‘f ‰·“x

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�æ�¼�@‰—�@‘æ3‰ñ�@”R—¿Œn‚v ‚f �ì‹Æ‰ï •½�¬16”N6ŒŽ21“ú

ILE Osaka

ILE Osaka

The size of revolver needs about 60 cm in the diameter

• The thermal load due to propellant gas is ~1.2 kW.

• Heat exchange rate with liquid He is ~ 0.1 W/cm2.

• The diameter of revolver is estimated to be 60 cm, which makes hard to obtain high rep-rate.

4 Hz -> 2 Hz x 2

1.2 kW

60 cm

Estimation of thermal load 1

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1 MW of electric power will be consumed to

operate a pneumatic injector.

Žº‰·

‚P‚O‚j

‰t‘Ì ’‚ ‘f ‰·“x

Radiation shield

3 hr

280W

470W

to cool the revolver(280+470x2)×100=120 kW

66 kW

to cool thermal radiation66 ×10=660 kW

160 kW

to cool targets and egg plates200kW

In total 980kW / injector

Estimation of thermal load 2

ILE Osaka

ILE Osaka

Summary

• Conceptual design of KOYO-F is continued basing on a wet wall.

Critical issue of wet wall seems chamber clearance to achieve 4 Hz rep-rate.

• In a future laser fusion reactor, final optics at the end of 30m-long beam duct can be protected from metal vapor using a rotary shutter and 0.1 Torr hydrogen gas.

The vapor (v=100m/s) will stop within 6m from the entrance of beam port.

• Fuel loading in mass production process will be carried out by thermal cavitation technique. Accuracy of fuel loading (goal, < 1%) is future issue.