23rd IAEA FEC - 1

Studying Ignition Schemes Studying Ignition Schemes on European Laser Facilitieson European Laser Facilities

S. JacquemotS. Jacquemot

23rd IAEA FEC11-16/10/2010, Daejeon

23rd IAEA FEC - 2

A dual European horizon

1 - a very-large-scale laser facility: the Laser MégaJouleto trustfully demonstrate indirectly-driven laser ignition at the MJ level

thanks to an improved target design & a series of validating experimental campaigns

2 – an ambitious project: HiPERtowards Inertial Fusion Energycurrently supporting numerical and experimental studies ofalternative ignition schemes & innovative technologies

23rd IAEA FEC - 3

� Czech Rep.: FZU/PALS & CTU Prague� France: CEA, LULI, CELIA & LPGP� Germany: GSI & MPQ� United Kingdom: STFC/RAL� Hungary: KFKI RMKI & Szeged� Italy: ENEA/Frascati, U. Milano-Bicocca, Roma “La Sapienza” & ILIL Pisa� Poland: IPPLM� Portugal: IST/GoLP� Spain: CIEMAT & UPM

Vulcan LULI2000

ABC

Phelix

HILL PALS

The key partners

23rd IAEA FEC - 4

The generic laser-target assembly for LMJ ID ICF

3 UV lasercones

high-Z (Au) hohlraum low-Z gas(HHe, <1mg/cc)

L~1cm, Φ~6mm

adequate pulse shaping�

spherical convergence ofaccurately timed shock waves

�isentropic compression & hot spot formation

polyimide windowΦ~3mm

solid fuel shell(cryo. DT) e~100µm

gaseous DT

uniformly doped ablator (e.g. CHGe)e~160µm

0.3mg/ccR~1.2mm

3.5MK550TW / 1.8MJ

23rd IAEA FEC - 5

Current status of the LMJ facilityup to 240 beams in 60 quads, up to 2 MJ/600TW

building commissioned, 2(/4) laser bays completed, target chamber being equippedcryo. target assembly under characterization & insertion systems validated

1st experiments end of 2014

PET

UTCC

PCC

Chambre de transfert

J. Ebradt CEA/DAN

23rd IAEA FEC - 6

* cocktail hohlraum (75%U-25%Au) to improve the hohlraum energetics* rugby-shaped hohlraumfor a significant x-ray driveenhancement

* gradually doped ablatorto reduce hydro. risks &control rad. preheating

* 160 laser beams in 2 cones

Improved target design provides flexibility

� 1.2 MJ – 330TW

C. Cherfils, D. Juraszek CEA/DIF

~10 mm

~3 mm

23rd IAEA FEC - 7

Laser-Plasma Interaction experiments on the LIL facility give confidence on the effectiveness of the implemented optical smoothing techniqueto control parametric instabilities

laser beams

LEH

λ0

λ0 + ∆λ0

∆L3ω gratings

1ω gratingsKDP 14GHz

1014 1015

Intensity [W/cm2]1014 1015

10

1Refle

ctivit

y (%)

0.2

20

SRSSBS

1014 1015

Intensity [W/cm2]1014 1015

10

1Refle

ctivit

y (%)

0.2

20

SRSSBS

C. Rousseaux CEA/DIF

simul. theo.

SRS

SBS

23rd IAEA FEC - 8

Rugby-shaped hohlraums allow improving the overall energeticsthanks to reduction of the wall surface (and thus of the wall losses) up to +25% expected in LMJ conditions

experiments on OMEGA (LLE, US) exhibit a significant increase of the radiative temperature(+16%)

leading to a record neutron flux (1.5 1010) for a D2 indirectly-driven implosion @20kJ

F. Philippe CEA/DIF

RugbyCylinder

23rd IAEA FEC - 9

VISAR 2ω VISAR ω VDC

F. Philippe CEA/DIF

The first 2 shock dynamics has been reproduced on LIL using a LMJ-relevant radiation drive

PS Al

2nd shock

1st shock

t0

time

23rd IAEA FEC - 10

3. Driverhigh repetition rate, low costgood “wallplug” efficiency &availability

4. Fusion schemerobust & simple target designhigh gain

1. Target factorymass production of low-cost targets2. Target engagementhigh rep. rate injection, tracking &shooting – survivability

5. Fusion chamberlong lifetime & low activation

6. Steam plantPout~0.4 GW � driver ηd~20% @ 20Hz � target G~100 & Ed~600kJ(shock ignition)

Perspectives: Inertial Fusion Energy (IFE)

23rd IAEA FEC - 11

The HiPER projectto demonstrate high repetition rate operation and solve power-production bottlenecks

in a single facility stepPETAL on LMJ:a forerunner to addressphysics issues

26 Eu partners

C. Edwards STFC, F. Amiranoff LULI, N. Blanchot CEA/CESTA

23rd IAEA FEC - 12

Preparatory Phase

Physics roadmapignition scheme down-select &

experimental validation (LMJ/PETAL)

1 & 10 kJ beamlines prototyping

Final design & cost analysis

Technology Developments & Risk Reduction

Technology roadmap

reactor concept design.

.

.

.

� power-to-grid demonstration in ~ 2040

...

� construction

C. Edwards STFC, F. Amiranoff LULI

23rd IAEA FEC - 13

Alternative ignition schemes allow reducing laser energy requirementsfast ignition & shock ignition both rely on decoupling direct drive target compression from ignition, using – as an external match - either a laser-accelerated fast particle beam or a strong shock

lateral hot spot / central hot spotlateral hot spot / central hot spot

23rd IAEA FEC - 14

An optimized irradiation configuration, using only 48 laser beams, has been found

2D multimode simulations show that the target ignites despite capsule deformation due to illumination non-uniformitiesreasonable power imbalance & pointing error can be borne if focal spot carefully optimized

M. Temporal UPM, B. Canaud CEA/DIF et al., S. Atzeni U. Rome « La Sapienza »

23rd IAEA FEC - 15

2D hydro, PIC & transport simulations allow following fast ignition for an asymmetric illumination

A. Debayle, J. Honrubia UPMet al.

and investigating influence of the electron beam divergence

increase of the ignition energy thresholdby a factor ~1/[1-θr/∆θ0]

23rd IAEA FEC - 16

First experiments at RAL on electron transport in pre-compressed matter provide valuable information to benchmark numerical codes

M. Koenig LULI, D. Batani U. Milano-Bicocca et al.

% of electrons passing throughthe whole cylinder

5 x 1018 W/cm2

160J/10ps

compression4x50J / 1ns

fast electron generationpolyimide cylinder with CH foam inside

(0.1-1 g/cc)

Proton radiography

X-ray radiography+ ps probe beam

good agreement with numerical simulations (MC code)gold shield

proton energy too low

Simulated

good agreement with numerical simulations (transmission)

Ni foilCu foil

Ni-Kαααα Ni-KββββCu-Kαααα Cu-Kββββ

HOPG spectrometer

Cu-Kα imager (side & rear)

detection of fast electrons in compressed matter

Cu-K

α/ N

i-Kβ

max comp.time (ns)

100 µm

23rd IAEA FEC - 17F. Perez LULI, A. Debayle UPM

1 g/cc1 g/cc2.5 ns

B field

fast electrons density

resistivity

2D Cu-Kα side

before stagnation: due to resistivity gradients, magnetic fields collimate the fast electron beamat stagnation: the shock converging to the center, the resistivity gradients disappear & the electron beam is no longer collimated

2D Cu-Kα side fast electrons density

B fieldresistivity

t=1.5 ns t=2 ns

Very good agreement between experiment and simulations

2D hybrid simulations show importance of resistivitygradients

23rd IAEA FEC - 18

Shock ignition leads to higher gain and lower energy threshold for a non-isobaric fuel assembly

mDT=0.01mg

mDT=0.1mg

mDT=1mg

ε increasing from 1 to 5mDT=5mg

mDT=0.01mg

mDT=0.1mg

mDT=1mg

ε increasing from 1 to 5mDT=5mg

X. Ribeyre et al. CELIA

Intens

ity(10

15W/

cm²) parametric instabilities hydro. instabilities

80kJ

1.5MJ

250kJ

h = 2.0

Implosion velocity (km/s)

risks due to hydrodynamic and parametric instabilities can be minimized thanks to homothetic scaling of the HiPER targeth = 0.5

h = 1.0

Implosion velocity (km/s)

Spike

inten

sity(

PW/cm

2 )

compression energy100kJ

2MJ

23rd IAEA FEC - 19

Experiments have already started to investigate LPI and shock formation at PALS & LULI2000

D. Batani U. Milano-Bicocca, P. Koester ILIL Pisa, J. Badziak IPPLM – S. Baton LULI et al.

backscattered light (SBS, SRS)time-resolved

1st shockI ~ 51013 W/cm2

“spike”I ~ 1015 W/cm2

VISAR

SOP

hot electrons

CH

Ti foil

SiO2CH

Ti foil

SiO2

tλ

ttλ

fiducial

1st shock

2nd shock

tt

tt

23rd IAEA FEC - 20

The European DPSSL program

100 J @ 10Hz & 6J @ 100Hz

none

1kJ @ 10 Hznone

100 J @ 10Hz7 J @ 2 Hz

150 J @ 0.1Hz12 J @ 0.003 Hz

Goal AchievementDPSSL Programs Gain medium Amplifier

architectureGermany

Yb: CaF2crystalsRT° and cryo gas cooled multi-slab

FranceYb:YAG

crystals & ceramicsRT° and cryo gas cooled active

mirrorUK

Yb:YAGceramics & glass

cryo gas cooled multi-slab

Czech Republictbd tbd

100 J @ 10Hz & 6J @ 100Hz

none

1kJ @ 10 Hznone

100 J @ 10Hz7 J @ 2 Hz

150 J @ 0.1Hz12 J @ 0.003 Hz

Goal AchievementDPSSL Programs Gain medium Amplifier

architectureGermany

Yb: CaF2crystalsRT° and cryo gas cooled multi-slab

FranceYb:YAG

crystals & ceramicsRT° and cryo gas cooled active

mirrorUK

Yb:YAGceramics & glass

cryo gas cooled multi-slab

Czech Republictbd tbd

J.-C. Chanteloup

23rd IAEA FEC - 21

SummaryCurrent experiments and target design improvements give confidence in demonstrating indirectly-driven ignition at ~1 MJ on NIF and then LMJ.It will be a major step towards determining the feasibility of ICF as an energy source.In the framework of the EURATOM keep-in-touch & the HiPER programs Europe has launched coordinated studies to: (i) choose the most suitable ignition scheme, thanks to innovative experiments and 2D numerical simulations, (ii) improve DPSSL driver and target technologies. with the support of LASERLAB-Europe for transnational access to laser facilities

23rd IAEA FEC - 22

23rd IAEA FEC - 23

Additional tricks could be employed to further reduce LPI risks and increase safety margins: 2ω operation or plasma-induced beam smoothing

0611030

creationbeam

interaction beam

CH50 µm

time

1.5 ns

creation interaction

0611030

creationbeam

interaction beam

CH50 µm

time

1.5 ns

creation interaction

(a)

LULI2000

LIL

S. Depierreux CEA/DIF, C. Labaune LULI

0 1 2 3 1015 W/cm2

3ω

RSBS(%)

10

1

0 1 2 3 1015 W/cm2

3ω

2ω

RSBS(%)

10

1

23rd IAEA FEC - 24

Fast electron transport has been studied on LULI2000 in well-characterized pre-plasmas

P. Norreys STFC, S. Baton LULI et al.

electrons are less divergent in steep-gradient plasmas (at high laser contrast)

2D Cu-Kα imager

HOPGAg-Kα & Cu-Kα

Conical spectrometerAl-Kα & Cu-Kα

Bremsstrahlung cannons

e- / p spectrometer

Hard X-ray spectrometer (LCS) Au-Ka & Ag-Ka

optical diagnostics• HISAC• OTR

1ps , 25-40 J1019 W/cm2

1ω / 2ω

2D Cu-Kα imager

HOPGAg-Kα & Cu-Kα

Conical spectrometerAl-Kα & Cu-Kα

Bremsstrahlung cannons

e- / p spectrometer

Hard X-ray spectrometer (LCS) Au-Ka & Ag-Ka

optical diagnostics• HISAC• OTR

1ps , 25-40 J1019 W/cm2

1ω / 2ω

ω 2ω

23rd IAEA FEC - 25

Realistic PIC simulations address one of the key issues for this scheme: parametric instabilities

V. Tikhonchuk CELIA, O. Klimo CTU Prague

ω/ω0

time(p

s)

SBSSRS

spike intensity above threshold� SRS & SBS growth observed, but:* transient SBS* absolute local (nc/4-nc/16) SRS associated with cavitation� strong laser energy absorption

Tcold = 6 kev

Thot = 29 kev

absorbed energy transported by 30 keVelectrons to the ablation zone� high amplitude shock wave generated in the dense shell

23rd IAEA FEC - 26

PALS experiments on shock formationin well-characterized pre-plasma conditions (x-ray deflectometry & spectroscopy)

D. Batani U. Milano-Bicocca, P. Koester ILIL Pisa, J. Badziak IPPLM

1keV plasma creation2 1013W/cm2, ω (1.3µm)

shock generation5 1015W/cm2, 3ω (0.44µm)

Al CH

wavelength (nm)

inten

sity

SRS < 5%

wavelength (nm)

inten

sity

SRS < 5%

20km/s20km/s

next (2011): characterize hot electrons

20km/s

SRS < 5%