1. 1CEA-DAM Ile-de-France High-Gain Direct-Drive Shock Ignition for the Laser Megajoule:prospects and first results. B. Canaud CEA, DAM, DIF France 7th Workshop Direct Drive and Fast Ignition May, 3-6, 2009 Prague, FCI2 Direct Drive @ 2 rings Density at stagnation 50100 Radius (µm) 50 100

2. 2CEA-DAM Ile-de-France Collaborators X. Ribeyre, M. Lafon, J.L. Feugeas, J. Breil, G. Schurtz CELIA, Bordeaux M. Temporal, R. Ramis ETSIA, Madrid, Spain

3. 3CEA-DAM Ile-de-France Standard LMJ direct drive illumination differs from indirect one by a more isotropic beam layout on the target chamber. a) Baseline LMJ Direct Driveb) LMJ Indirect Drive 33.2° (10 beams) 49° (10 beams) 59.5° (10 beams) Z DT 33.2° (10 beams) 78° (10 beams) 59.5° (10 beams) Z DT  Quad Each LMJ beamlet is limited by its power max: P max ≤ 2.5 TW.

4. 4CEA-DAM Ile-de-France A few years ago, we proposed a new direct drive configuration with indirect drive beam layout [*]… b) LMJ Indirect Drivea) Baseline LMJ Direct Drive 33.2° (10 beams) 78° (10 beams) 59.5° (10 beams) DT 33.2° (10 beams) 49° (10 beams) 59.5° (10 beams) Z DT  … but with only 1.2 MJ of laser energy. (*) Canaud B. et al, Plasmas Phys. Cont. Fusion, 49, B601 (2007).

5. 5CEA-DAM Ile-de-France 49° (45%) 59.5° (55%) Z early time late time large spot narrow spot Focal spot zooming increases laser-target coupling efficiency [**]. 1 beam large, 3 narrows on each quad. With zooming and 2 rings, Gain=32 with 1 MJ laser. With zooming and 2 rings, Gain=32 with 1 MJ laser. A new 2-rings baseline( * ) high-gain Direct-Drive design has been proposed with focal spot zooming. (*) Canaud B. et al, Nucl. Fus., 47, 1642 (2007) 1 µm CH DTgas DT ice Wetted foam 165 µ m 134 µ m 1341 µ m Adiabat = 3.5 V=4.10 5 m/s FCI2 Direct Drive @ 2 rings Density at stagnation 50100 Radius (µm) 50 100 (**) Canaud B. et al, Nucl. Fus., 45, L43 (2005)

6. 6CEA-DAM Ile-de-France Laser energy (MJ) with 3D ray-tracing Thermonuclear gain Adiabat = 3.5 V=4.10 5 m/s 0.1 1 10 100 0.41 0.63 w/o Zooming w/ Zooming LMJ design with zooming Without zooming, the target is marginally igniting. LMJ design without zooming  : adiabat v : implosion velocity Homothetic target family curve

7. 7CEA-DAM Ile-de-France Isobaric ignition concerns standard direct drive ignition. Alternative exists to displace the energy threshold towards lower energies, keeping constant the implosion target parameters ( ,v). Hot-spot DT fuel radius T  P iso Isobaric Ignition threshold  : adiabatic parameter v : implosion velocity Burn of Hot spot Burn of DT fuel (*) Betti R. et al, Phys.Rev. Lett., 98, 155001 (2007) Non-isobaric ignition reduces the energy threshold for ignition. Hot spot DT fuel radius T  P non iso where P iso

8. 8CEA-DAM Ile-de-France A low-isentrope compression is obtained by a usual pulse shape. Non isobaric conditions can be achieved by launching a strong shock at the end of the implosion. An additional spike launches a strong shock in the target. t spike P spike

9. 9CEA-DAM Ile-de-France Shock can be created by the 33°-ring of the LMJ(*). 33.2° (10 beams) 49° (10 beams) 59.5° (10 beams) Z DT } (*) Ribeyre X. et al, Plasmas Phys. Cont. Fusion, 51, 015013 (2009). 2D CHIC simulations of bipolar shock ignition show a good sphericity of the ignitor shock.

10. 10CEA-DAM Ile-de-France The target is far below the ignition threshold. Fast-ignitor (*) targets can be considered for Shock Ignition ( + ). (*) Ribeyre X. et al, Plasmas Phys. Cont. Fusion, 50, 025007 (2008). ( + ) Ribeyre X. et al, Plasmas Phys. Cont. Fusion, 51, 015013 (2009) t spike P spike (TW) 100 200 50 10 20 30 40 10 P (TW) t (ns) t spike P spike 200 ps 300 ps 200 ps 10 9.510.4 DTgas DT ice @ 250 kg/m 3 210 µ m 1040 µ m HiPER (*) baseline target 1D implosion data Absorbed energy110 kJ Adiabat 1 Implosion velocity 290 km/s Density Max600 g/cm 3 Areal density max1.5 g/cm 2 P=180 TW E Th =20 MJ

11. 11CEA-DAM Ile-de-France With the spike and 2 rings, G 1D =50 with 0.2 MJ absorbed laser. With the spike and 2 rings, G 1D =50 with 0.2 MJ absorbed laser. Marginally igniting standard direct drive target can be triggered by shock ignition (SI). 1 µm CH DTgas DT ice Wetted foam 120 µ m 100 µ m 960 µ m Baseline Direct Drive  = 3.5 V=400 km/s 50 100 150 7 P (TW) t (ns) t spike P spike 200 ps 300 ps 200 ps 1D implosion data Absorbed energy200 kJ Density Max500 g/cm 3 Areal density max1. g/cm 2 With SI (@max) Pspike190 TW Density Max1700 g/cm 3 Areal density max1.27 g/cm 2 Eth11 MJ 0,01 0,1 1 10 100 0,010,1 E thermonuclear (MJ) E kinetic (MJ) With Shock ignition

12. 12CEA-DAM Ile-de-France Different targets from the FI-family should be considered for LMJ. 100 KJ-absorbed500 KJ-absorbed  =1 v = 290 km/s  max = 600 g/cm 3 1D implosion data Absorbed energy 500 kJ  r 2 g/cm 2 Spike Laser Power max 110 TW Abs Intensity 2e15 W/cm 2 Thermonuclear rho r 2.2 g/cm 2 Energy Th. 133 MJ 850 KJ-absorbed 1D implosion data Absorbed energy 850 kJ  r 2.24 g/cm 2 Spike Laser Power 100 TW Abs Intensity 1e15 W/cm 2 Thermonuclear rho r 2.4 g/cm 2 Energy Th. 260 MJ 2090 µ m DT gas DT ice 420 µ m 1750 µ m DT gas DT ice 350 µ m 1D implosion data Absorbed energy 200 kJ  r 1.6 g/cm 2 Spike Laser Power 160 TW Abs Intensity 5e15 W/cm 2 Thermonuclear rho r 2 g/cm 2 Energy Th. 44 MJ 1D implosion data Absorbed energy 100 kJ  r 1.2 g/cm 2 Spike Laser Power max 120 TW Abs Intensity 6e15 W/cm 2 Thermonuclear rho r 1.7 g/cm 2 Energy Th. 18 MJ 1040 µ m DT gas DT ice 210 µ m 200 KJ-absorbed 1240 µ m DT gas DT ice 250 µ m

13. 13CEA-DAM Ile-de-France The power in the spike is a key parameter for SI. 100 KJ-absorbed  =1 v = 290 km/s  max = 600 g/cm 3 1040 µ m DT gas DT ice 210 µ m 200 KJ-absorbed 1240 µ m DT gas DT ice 250 µ m Need between 200 and 300 TW for ignitor pulses : The 33° rings will produce only 200 TW We need to redefine a target design and to improve the laser- target coupling efficiency for the ignitor pulses. 1D implosion data Absorbed energy 200 kJ  r 1.6 g/cm 2 Spike Laser Power 160 TW Abs Intensity 5e15 W/cm 2 Thermonuclear  r 2 g/cm 2 Energy Th. 44 MJ 1D implosion data Absorbed energy 100 kJ  r 1.2 g/cm 2 Spike Laser Power max 120 TW Abs Intensity 6e15 W/cm 2 Thermonuclear  r 1.7 g/cm 2 Energy Th. 18 MJ

14. 14CEA-DAM Ile-de-France Low energy for fuel assembly should allow to use only the 49° ring. 100 KJ-absorbed  =1 v = 290 km/s  max = 600 g/cm 3 1D implosion data Absorbed energy 200 kJ  r 1.6 g/cm 2 Spike Laser Power 160 TW Abs Intensity 5e15 W/cm 2 Thermonuclear  r 2 g/cm 2 Energy Th. 44 MJ 1D implosion data Absorbed energy 100 kJ  r 1.2 g/cm 2 Spike Laser Power max 120 TW Abs Intensity 6e15 W/cm 2 Thermonuclear  r 1.7 g/cm 2 Energy Th. 18 MJ 1040 µ m DT gas DT ice 210 µ m 200 KJ-absorbed 1240 µ m DT gas DT ice 250 µ m b) LMJ Indirect Drive 33.2° 49° 59.5° Z DT We need more than 200 kJ to assemble the target: the 49° rings should be a good candidate. We need to improve the irradiation uniformity.

15. 15CEA-DAM Ile-de-France High gain direct drive Shock ignition on LMJ requires to address several physical key issues. Summary Standard direct drive fuel assembly is achievable with a part of X drive beams (rings @ 49° et 59°5). Using the ring @ 49° needs well characterize and to improve (if necessary) the irradiation uniformity (PDD, Green House Target, …) Shock ignition with the last beams (rings @ 33°) should be possible but we may need to redefine a target with lower power ignitor. Extremely high gains could be achieved on LMJ : E 1D absorbed ~ 0.2 MJ, E th ~ 40 MJ Restrictions Parametric instabilities driven by the shock ignitor could be problematic. Hydrodynamic stability of the capsule must be addressed Unknown Physics (eos, heat conductivity, kinetic effects,…) could be limiting. … 1D design must be revisited (wetted foam, reduced IFAR, …). Fully 2D calculations (with ray-tracing 3D) have to be done for LMJ. In addition, to be done …