StudyingStudying IgnitionIgnition SchemesSchemes onon EuropeanEuropean LaserLaser FacilitiesFacilities

S. Jacquemot

23 rd IAEA FEC

11-16/10/2010,rd Daejeon 23 IAEA FEC - 1 A dual European horizon

1 - a very-large-scale facility: the Laser MégaJoule

to 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: HiPER

towards Inertial Fusion Energy

currently supporting numerical and experimental studies of alternative ignition schemes & innovative technologies

rd 23 IAEA FEC - 2 The key partners Phelix  Czech Rep.: FZU/PALS & CTU Prague

 France: CEA, LULI, CELIA & LPGP HILL PALS  Germany: GSI & MPQ

 United Kingdom: STFC/RAL

 Hungary: KFKI RMKI & Szeged

 Italy: ENEA/Frascati, U. Milano-Bicocca, Roma “La Sapienza” & ILIL Pisa

ABC  Poland: IPPLM

 Portugal: IST/GoLP

 Spain: CIEMAT & UPM Vulcan LULI2000

rd 23 IAEA FEC - 3 The generic laser-target assembly for LMJ ID ICF

Φ L~1cm, ~6mm uniformly doped ablator (e.g. CHGe) e~160µm polyimid solid fuel shell e window 3 UV laser Φ e~100µm ~3mm cones (cryo. DT) R~1.2mm gaseous DT 0.3mg/cc high-Z (Au) hohlraum low-Z gas (HHe, <1mg/cc)

550TW / 1.8MJ adequate pulse shaping 3.5MK  spherical convergence of accurately timed shock waves  isentropic compression & hot spot formation

rd 23 IAEA FEC - 4 Current status of the LMJ facility up to 240 beams in 60 quads, up to 2 MJ/600TW

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

UTCC

Chambre de transfert

1st experiments end of 2014 rd J. Ebradt CEA/DAN 23 IAEA FEC - 5 Improved target design provides flexibility

* cocktail hohlraum (75%U-25%Au) to improve the hohlraum energetics ~10 mm * rugby-shaped hohlraum for a significant x-ray drive enhancement ~3 mm * gradually doped ablator to reduce hydro. risks & control rad. preheating

* 160 laser beams in 2 cones

 1.2 MJ – 330TW

rd C. Cherfils, D. Juraszek CEA/DIF 23 IAEA FEC - 6 Laser- Interaction experiments on the LIL facility give confidence on the effectiveness of the implemented optical smoothing technique to control parametric instabilities

λ0 laser beams SRS ω ∆L 3 gratings λ λ 0 + ∆ 0

KDP 14GHz SBS LEH ω 1 gratings

20 SBS 10 SRS

1 Reflectivity (%) (%) Reflectivity Reflectivity

simul. theo. 0.2 14 15 14 15 10 10 10 10 2 Intensity [W/cm ]

rd C. Rousseaux CEA/DIF 23 IAEA FEC - 7 Rugby-shaped hohlraums allow improving the overall energetics thanks 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%)

Rugby

Cylinder leading to a record flux (1.5 10 10 ) for a D 2 indirectly-driven implosion @20kJ

rd F. Philippe CEA/DIF 23 IAEA FEC - 8 The first 2 shock dynamics has been reproduced on LIL using a LMJ- relevant radiation drive

VISAR 2 ω VISAR ω VDC

2nd shock time 1st shock

t0 PS Al

rd F. Philippe CEA/DIF 23 IAEA FEC - 9 Perspectives: Inertial Fusion Energy (IFE)

3. Driver 1. Target factory high repetition rate, low cost mass production of low-cost targets good “wallplug” efficiency & availability 2. Target engagement high rep. rate injection, tracking & shooting – survivability

4. Fusion scheme 5. Fusion chamber robust & simple target design long lifetime & low activation high

6. Steam plant

  Pout ~0.4 GW driver ηd~20% @ 20Hz target G~100 & E d~600kJ (shock ignition)

rd 23 IAEA FEC - 10 The HiPER project to demonstrate high repetition rate operation and solve power-production bottlenecks

26 Eu partners

in a single facility step

PETAL on LMJ: a forerunner to address physics issues

rd C. Edwards STFC, F. Amiranoff LULI, N. Blanchot CEA/CESTA 23 IAEA FEC - 11 . . .

Preparatory Technology Developments & Final design & Phase Risk Reduction cost analysis

 construction ignition scheme down-select & Physics roadmap experimental validation (LMJ/PETAL)

1 & 10 kJ beamlines prototyping . Technology roadmap . .

reactor concept design.

 power-to-grid demonstration in ~ 2040

rd C. Edwards STFC, F. Amiranoff LULI 23 IAEA FEC - 12 Alternative ignition schemes allow reducing laser energy requirements fast 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 spot

rd 23 IAEA FEC - 13 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- uniformities

reasonable power imbalance & pointing error can be borne if focal spot carefully optimized

et al rd M. Temporal UPM, B. Canaud CEA/DIF ., S. Atzeni U. Rome « La Sapienza » 23 IAEA FEC - 14 2D hydro, PIC & transport simulations allow following fast ignition for an asymmetric illumination and investigating influence of the electron beam divergence

increase of the ignition energy threshold by a factor ~1/[1-θr/∆θ 0]

et al rd A. Debayle, J. Honrubia UPM . 23 IAEA FEC - 15 First experiments at RAL on electron transport in pre-compressed matter provide valuable information to benchmark numerical codes Cu foil Proton radiography Ni foil good agreement with gold compression numerical simulations shield 4x50J / 1ns (MC code)

proton energy too low polyimide cylinder fast electron generation 18 2 with CH foam inside 5 x 10 W/cm + ps probe beam (0.1-1 g/cc) 160J/10ps X-ray radiography

HOPG spectrometer Simulated Ni-Kααα Cu-Kααα Ni-Kβββ Cu-Kβββ % of electrons passing through the whole cylinder good agreement with numerical

β simulations (transmission)

100 µm / Ni-K

α Cu-Kα imager (side & rear) max comp. Cu-K

time (ns) detection of fast electrons in compressed matter

et al. rd M. Koenig LULI, D. Batani U. Milano-Bicocca 23 IAEA FEC - 16 2D hybrid simulations show importance of resistivity gradients

t=1.5 ns t=2 ns 2.5 ns

1 g/cc

resistivity B field resistivity B field

α 2D Cu-K side fast electrons density 2D Cu-Kα side fast electrons density

Very good agreement between experiment and simulations before stagnation: due to resistivity gradients, magnetic fields collimate the fast electron beam at stagnation: the shock converging to the center, the resistivity gradients disappear & the electron beam is no longer collimated

rd F. Perez LULI, A. Debayle UPM 23 IAEA FEC - 17 Shock ignition leads to higher gain and lower energy threshold for a non-isobaric fuel assembly ) ε 2 increasing from 1 to 5 compression energy mDT =5mg 100kJ mDT =1mg

mDT =0.1mg 2MJ

mDT =0.01mg Spike intensity (PW/cm

Implosion velocity (km/s) hydro. instabilities parametric instabilities

W/cm²) 80kJ risks due to hydrodynamic and parametric 15 h = 0.5 instabilities can be minimized thanks to 250kJ homothetic scaling of the HiPER target h = 1.0

Intensity (10 1.5MJ h = 2.0

Implosion velocity (km/s)

rd X. Ribeyre et al. CELIA 23 IAEA FEC - 18 Experiments have already started to investigate LPI and shock formation at PALS & LULI2000

fiducial backscattered light (SBS, SRS) λ time-resolved t

CH SiO 2 “spike” 15 2 Ti foil t I ~ 10 W/cm SOP

1st shock VISAR I ~ 510 13 W/cm 2 hot electrons 1st shock 2nd shock

t

rd D. Batani U. Milano-Bicocca, P. Koester ILIL Pisa, J. Badziak IPPLM – S. Baton LULI et al. 23 IAEA FEC - 19 The European DPSSL program

Goal Amplifier DPSSL Programs Gain medium Achievement architecture Germany 150 J @ 0.1Hz Yb: CaF 2 RT° and cryo gas 12 J @ 0.003 Hz crystals cooled multi-slab

France RT° and cryo gas 100 J @ 10Hz Yb:YAG cooled active 7 J @ 2 Hz crystals & ceramics mirror

UK 1kJ @ 10 Hz Yb:YAG cryo gas none ceramics & glass cooled multi-slab

Czech Republic 100 J @ 10Hz & 6J @ 100Hz tbd tbd none

rd J.-C. Chanteloup 23 IAEA FEC - 20 Summary

Current 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

rd 23 IAEA FEC - 21 rd 23 IAEA FEC - 22 Additional tricks could be employed to further reduce LPI risks and ω increase safety margins: 2 operation or plasma-induced beam smoothing

creation interaction RSBS (%) LULI2000 time 1.5 ns 3ω 10

2ω creation beam CH 50 µm 1 interaction beam 0611030 0 1 2 3 10 15 W/cm 2 LIL (a)

rd S. Depierreux CEA/DIF, C. Labaune LULI 23 IAEA FEC - 23 Fast electron transport has been studied on LULI2000 in well-characterized pre-plasmas optical diagnostics • HISAC α • 2D Cu-K imager OTR

e- / p spectrometer

Conical spectrometer α α Al-K & Cu-K 1ps , 25-40 J HOPG 19 2 α α 10 W/cm Ag-K & Cu-K ω ω 1 / 2

Bremsstrahlung cannons

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

ω 2ω

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

et al. rd P. Norreys STFC, S. Baton LULI 23 IAEA FEC - 24 Realistic PIC simulations address one of the key issues for this scheme: parametric instabilities

spike intensity above threshold  SRS & SBS growth observed, but:

* transient SBS * absolute local (n /4-n /16) SRS

time(ps) c c associated with cavitation SRS SBS  strong laser energy absorption

ω/ω 0 Tcold = 6 kev

absorbed energy transported by 30 keV electrons to the ablation zone  high amplitude shock wave generated Thot = 29 kev in the dense shell

rd V. Tikhonchuk CELIA, O. Klimo CTU Prague 23 IAEA FEC - 25 PALS experiments on shock formation in well-characterized pre-plasma conditions (x-ray deflectometry & )

SRS < 5% SRS < 5% intensity intensity

wavelength (nm)

20km/s20km/s Al CH

shock generation 1keV plasma creation 15 2 ω next (2011): characterize hot electrons 13 2 ω 5 10 W/cm , 3 (0.44µm) 2 10 W/cm , (1.3µm) rd D. Batani U. Milano-Bicocca, P. Koester ILIL Pisa, J. Badziak IPPLM 23 IAEA FEC - 26