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S.Yu.Gus’kov. LPI RAS

S.Yu.Gus’kov. LPI RAS.

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S.Yu.Gus’kov. LPI RAS

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  1. S.Yu.Gus’kov. LPI RAS Fast Ignition by Detonating Hydrodynamic FlowS.Yu. Gus’kov*, M. Murakami***P.N. Lebedev Physical Institute of Russian Academy of Sciences, Moscow, Russia**Institute of Laser Engineering. Osaka University. Japan 7-th Direct Drive and Fast Ignition Workshop. May 3-6, 2009. Prague Contents: 1. Fast ignition by hydrodynamic flow 2. Fast ignition by detonating hydrodynamic flow - “target from target” ignition 3. Conclusion: Practicability of fast ignition at the impactor velocity of 300-500 km/s

  2. S.Yu.Gus’kov. LPI RAS Fast ignition by hydrodynamic flow

  3. S.Yu.Gus’kov. LPI RAS Fast Ignition Drivers Compression  =(300 - 500) g/cm3 R = (3 - 4) g/cm2 Ignition T=10 keV Rign = 0. 4 g/cm2 Igniting Drivers: Fast particles from laser-produced plasma • electrons(Ee ~ 0.5-1.5 MeV) • light ions (Ei ~ 10 -100 MeV/nuclon) Laser : IL > 1019 W/cm2, L< 10-20 ps. Experiments:CD-target + cone RAL (UK), ILE (Japan) Neutron yield: 105  106 Hydrodynamic pulse Iu3 , u ~1000 km/s Laser: IL  1015 W/cm2, L 1 ns Experiments:CD-target + cone ILE (Japan) Neutron yield: 105  106 Igniting Driver Energy: Eign = (10-15)/1002 kJ Eign = (10-30) kJ Beam radius: Rign=Rign /  Rign  10-30mPulse duration: ign = Rign/108ign 10 ps Intensity: Iign (1018 - 1019) W/cm2

  4. S.Yu.Gus’kov. LPI RAS Ignition of the Impactor Ignition of the Target R=3-4 g/cm2 =300-500 g/cm3 Iign t (CDTTign)3/2, ign 0.5(im /t)1/2 Iim (CDTTign)3/2 u  1.5(t /im)1/2(CDTTign)1/2 u  (CDTTign)1/2 R=3-4 g/cm2 t = im  u = 1500 km/s, t = 10im  u > 4000 km/s, u ~1000 km/s =300-500 g/cm3 General Requirements for Impact Ignition t=300-500 g/cm3 ! Tign=10keV. I imu3 Theoretical limit of low-entropy laser-driven acceleration of a foil: 1700 km/s

  5. S.Yu.Gus’kov. LPI RAS Profiling laser pulse Simple laser pulse Hydrodynamic fast ignition Impact along a cone  ~ 1 g/cm3  V ~ 1000 km/s, M.Murakami, H. Nagatomo Nucl. Inst. & Meth. Phys. Res. A544, 67, 2005 Compression in a conical target. Detonating flow.  ~ (100-200) g/cm3 V ~ (500 - 300) km/s, S. Gus’kov, M.Murakami XXX ECLIM, 2008 1000 km/s 300 km/ • ILE (Osaka University, Japan) experiments on impact ignition, EL~ (1-3) kJ, 3: • Acceleration of the foil up to record velocity: 600–700 km/s. • Impact neutron generation:(1 -2) 106 DD-neutrons/shot.

  6. S.Yu.Gus’kov. LPI RAS Laser energy :1.3 kJ Spot size : 300 mm f Laser energy :1.9 kJ Spot size : 300 mm f 600 mm 600 mm laser laser CH plane 300 mmt Be frame Be plane (weight) Be frame CD foils 20 mmt Main fuel impactor CD foils 20 mmt Laser energy :1.9 kJ Spot size : 300 mm f laser Be frame CD foil 20 mmt ILE planar impact ignition experiments Watari T, Sakaiya T, Azachi H et al Neutron generation from impact fast ignition Proc. 5-th IFSA conference (Kobe, Japan, September 2007) 1. CD-foil - CD-target impact 3. CD-foil - CH-target impact 2. CD-foil - CD-target impact N: 106  N: 8.3105 >> N: 1.3105 1) impact nature of neutron generation and 2) neutron generation in impact-produced plasma of impactor

  7. S.Yu.Gus’kov. LPI RAS Plastic scintillator 18 cm f × 2.5 cm 52° 178 cm Target chamber 190 cm 25° 168° Pb 10 cm 80° MANDALA 47 cm 311 cm target 1344 cm Plastic scintillator 10 cm f × 5 cm 421 detectors P M T ILE spherical impact ignition experiments Watari T, Sakaiya T, Azachi H et al. Neutron generation from impact fast ignition. Proc. 5-th IFSA conference (Kobe, Japan, September 2007 1. Nmax= 2106 2. Ti=1.59 keV 3. Nmax corresponds to coincidence of the moments of maximal compression and impact

  8. S.Yu.Gus’kov. LPI RAS Impactor’s state before collision. Impactor’s density and velocity distributions along the central axis. L = 600 mm, t = 1.8 ns L = 1000 mm, t = 2 ns u u r r < u 600 km/s u 800 km/s > r  0.2 g / cc r  0.08 g /cc

  9. S.Yu.Gus’kov. LPI RAS Impact-produced plasma of impactor and target Density, ion and electron temperature distributions along the central axis << L = 600 mm, t = 1.8 ns N 106 N 6.3106 L = 1000 mm, t = 2 ns Target Impactor Target Impactor Ti > Te Ti > Te r r Ti=Te Ti=Te Impactor Ti  2.2 keV, Te  1.2 keV r  0.18 g/cc Impactor Ti  6.2 keV, Te 1.8 keV r  0.12 g/cc Target Ti  80 eV, r  3.8 g/cc Target Ti  60 eV, r  3.8 g/cc

  10. S.Yu.Gus’kov. LPI RAS Gekko/HIPER • Impactor’s density significantly less than target’s density: • imp  0.6 g/cm3 << t  4 g/cm3 • Predominant heating of impactor’s ions,Ti>>Te . Equilibrium target’s plasma Ti=Te . Impactor’s temperature significantly larger than target’s temperature: • Timp  (1.5 -3) keV >> Tt  (0.1 -0.2) keV • Neutron yield from impactor significantly larger than neutron yield from the target: • Nm  107 >> Nm  106 •  • Confirmation of the approach: • initial ignition of impactor and subsequent propagation of detonation wave • from impactor to compressed thermonuclear fuel of ICF-target

  11. S.Yu.Gus’kov. LPI RAS Fast ignition by detonating hydrodynamic flow

  12. S.Yu.Gus’kov. LPI RAS Detonating impactor Development of “Cone-Guided Impactor” to “Target inside Target” Ignition by Detonating Impactor - “Target From Target” Ignition Two well-known ICF-methods: 1. Profiled Laser Pulseand 2. Initial Density Distribution Multi-layer cone target 1. Cone target with homogeneous DT-fuel and profiled laser pulse 2. Cone target with spatial distributed density Ablator Pusher Igniter Cone target Cone target Cone target ICF-target ICF-target ICF-target

  13. S.Yu.Gus’kov. LPI RAS General requirement for ignition by detonating DT-impactor 1. Ignition of the impactor: 2. Detonation wave to DT-fuel: United requirement : Minimal ignition energy, m= t : Factor of exceeding: m t

  14. S.Yu.Gus’kov. LPI RAS “Target from Target” Ignition by Three-Layer Cone Target

  15. S.Yu.Gus’kov. LPI RAS • Three-layer cone target • 1. Ablator. • Light-element material: (CH)n-plastics, Be, Al and others. • Function: Acceleration of impactor  laser light absorption, ablation pressure creation. • Totally evaporated at the acceleration stage. • 2. Pusher. • Heavy-element material: Cu, Pb, Au and others. • Function: Impact-driven adiabatic compression of the igniter. • 3. DT-ice Igniter. • Function: Self-burning and ignition of ICF-target DT fuel by the detonation wave

  16. S.Yu.Gus’kov. LPI RAS Statement of the Problem. Planar Approximation. Pressure in the igniter at a burning stage: R=0.4 г/см2, T=10 keV, =100 г/см2  P~100-200 Gbar 1. Deceleration of the igniter by first shock wave, Pb0 << Pt 2. Deceleration of the pusher and adiabatic compression of the ignitor, Pb>>Pb0 3. Shock wave in ICF-Target DT-fuel; Effect of DT-fuel compressibility, Pb>Pt

  17. S.Yu.Gus’kov. LPI RAS Compression and heating of the igniter The moment of maximal compression: deceleration of the impactor down to the velocity of shock wave in ICF-target DT-fuel Residual kinetic energy of the impactor Energy of shock wave in ICF-target DT-fuel Adiabatic compression at the initial entropy from first shock wave: 1. Residual kinetic energy of the impactor: 2. Energy of shock wave in ICF-target DT-fuel:

  18. S.Yu.Gus’kov. LPI RAS Final state of the igniter Exact solution for m= s=t=: Compressibility factor “Uncompressible” solution Internal energy of igniter Uncompressible ICF-target fuel: Pb/Pw  1100,m  75 g/cm3; T=10 keV, at um 365 km/s; energy factor, 0.25 Au-pusher, Ms/Mm=20 Compressible ICF-target fuel: Pb/Pw  700; m  52 g/cm3; T=10 keV, at um 410 km/s; energy factor, 0.18

  19. S.Yu.Gus’kov. LPI RAS Final igniter density and velocity of ignition Pusher and igniter mass ratio vs final igniter density 1, 2, 3, 4 - energy factor, Em /E0 = 0.3 5, 6, 7, 8 - energy factor, Em /E0 = 0.5 Tig=10 keV: initial impactor velocity vs final igniter density t=500g/cc t=300g/cc t=200g/cc - - - - uncompressible ICF-target fuel u  330 km/s Au-pusher: Mpusher/Migniter 38 DT-igniter, ()ig=0.4 g/cm2: ig  40 m  Migniter 4 10-5 g Mpusher 1.5 10-4 g Initial: Eimpactor  70 kJ Final: Eigniter  40 kJ t=300 g/cm3 Eigniter/Eimpactor = 0,56 ig=100 g/cm3

  20. S.Yu.Gus’kov. LPI RAS Conical three - layer igniting target design

  21. S.Yu.Gus’kov. LPI RAS Igniting target. Requirements to the design  2R0 Cone opening angle   400-600 (R)ig , ig L (R)t , t Ignition of the igniter: (R)ig=0.4 g/cm2 High gain of ICF-target (R)t=3-4 g/cm2 Shell velocity: Evaporation - 50%, M0 / Mf = 2  Mass of ablator = a half of total mass,   0.3, u  0.57(I2)1/3 R0 0.153 cm, L0. 32 cm,  19.5ns Eimp=70 kJ, u = 3.3 107 cm/s, =0.3, =50o,  = 0.35 m

  22. S.Yu.Gus’kov. LPI RAS Igniting conical target design R0 0.153 cm DT-igniter: Migniter 4 10-5 g Au-pusher: Mpusher 1.5 10-4 g Be-ablator: Mablator=Mpusher Elaser= Eimpactor / Kabs Eimpactor  70 kJ  = 0.3, Kabs= 0.7 Elaser 320 kJ igniter  21,3 m pusher  10.7 m ablator  115.6 m  2R00.3 cm 115.6 m  10.7 m  21,3 m L  0. 32 cm =50o

  23. Conclusion:Practicability of hydrodynamic ignition at the velocity of 300-500 km/s • 1. Fast Ignition by Detonating Hydrodynamical Flow • Approach of “Target from Target” ignition • Conical three-layer igniting target: • Ignition at the initial velocity of hydrodynamical flow 330 km/s • and final density of detonating flow 100 g/cm3 • Laser parameters: EL= 320 kJ, L= 19.5 ns • 2. Key points: • Hydrodynamic instability • Impactor’s state before impact • EOS of heavy pusher 3. Experiments: collision of multi-layer impactor accelerated along conical or cyllindrical channels with a massive plane target.

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