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 laser 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-Plasma 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 neutron 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 gain
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 & spectroscopy)
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