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Outline of this talk

Impact Fast Ignition as Another Pathway to Laser Fusion. Outline of this talk. M. MURAKAMI. Institute of Laser Engineering, Osaka University, Japan. In collaboration with. １） Introduction & present status 2 ） Impact Ignition 3 ） Super-high velocity experiment

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Outline of this talk

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  1. Impact Fast Ignition as Another Pathway to Laser Fusion Outline of this talk M. MURAKAMI Institute of Laser Engineering, Osaka University, Japan In collaboration with １）Introduction & present status 2）Impact Ignition 3）Super-high velocity experiment 4) Integrate target experiment T. Sakaiya, H. Saito, H. Azechi, K. Otani, T. Watari, K. Takeda, D. Ichinose, H. Hosoda, S. Fujioka, K. Shigemori, M. Nakai, H. Shiraga, H. Nagatomo, A. Sunahara, and K. Mima ILE (Japan) M. Karasik, J. Gardner, J. Bates, D. Colombant, J. Weber, Y. Aglitskiy, A. Velikovich and S. Obenschain NRL (USA)

  2. Schematic picture and features of Impact Fast Ignition Target ILE Osaka Requirement for Ignition Impactor: Kinetic energy → Thermal energy ( T = 5 keV ) v = 1000 km/s Momentum ( , a= 3,rcore= 200 g/cc) r = 5 g/cc Feature of Impact Fast Ignition (IFI) 1. Simple physics 2. High gain 3. Low cost Ref. M. Murakami and H. Nagatomo, Nucl. Instrum. Meth. Phys. Res. A 544, 67 (2005).

  3. Gain curve expected for Impact Fast Ignition

  4. 1kg/cc (1000 times the solid density) compression has been demonstrated Azechi et al., Laser& Particle Beams 1990

  5. Density measurement with a Cu witness foil impactor X-ray Cu-foil UV emission from rear surface Of the witness foil

  6. Phys. Rev. Lett. 92 (2004) 195001

  7. Suppression of RT instability Rayleigh-Taylor instability is suppressed by the radiation from doped high-Z material. ILE Osaka Suppression technique of Rayleigh-Taylor (RT) instability ・High-Z doping (CHBr): Ref.S. Fujioka et al., Phys. Rev. Lett. 92, 195001 (2004). t = 3.5 ns t = 2.6 ns CH 40 µmt CHBr(3%) 13.5 µmt 2D sim.: J.H.Gardner @NRL

  8. By controlling the Br-dope, we could optimize the acceleration performance. CHBr targets Laser energy: 1.5 kJ Reference: CH 2.5 mg/cm2 190 km/s (300 km/s) 350 km/s #29527 #29517 CHBr 3% 300 mm 2 ns 2 ns 400 km/s (600 km/s) #29529 #29535 400 km/s (550 km/s) CHBr 0.3% 300 mm 2.5 mg/cm2 1.7 mg/cm2

  9. We have observed a maximum velocity, 650 km/s, ever achieved The super-high velocity of 1000 km/s seems to be achievable with appropriate ablator/pulse design.

  10. Integrated experiment The impactor of hemispherical fuel impacts to the pre-compressed main fuel. ILE Osaka Experimental condition Main fuel: Laser: 2w, E = 3 kJ, 1.3 ns-Gaussian shape Target: CD shell 7 mmt, 500 mmf Impactor: Laser: 2w, I ~ 200 TW/cm2 , 1.3 ns-Gaussian shape Target: hemispherical CD 10 mmt, 500 mmf

  11. Experimental procedure The plastic scintillators were arranged in various directions. ILE Osaka Experimental setup (Top view) 2 3 Plastic scintillator 18 cm f × 2.5 cm 178 cm 52° Target chamber 190 cm 25° Pb 10 cm 80° 168° 4 311 cm 47 cm Pb 6 cm Target 1 P M T Plastic scintillator 10 cm f × 5 cm

  12. Experiment results Neutrons are very likely to have thermal origin. ILE Osaka Energy (MeV) Neutron yield Distance: 47 cm Angle: 168° Angle( 168゜): 1.8 × 106 ±15% Angle( 25゜) : 1.6 × 106 ±13% Angle( 80゜) : 1.8 × 106 ±19% Angle( 52゜) : 2.0 × 106 ±13% X rays Distance: 190 cm Angle: 25° Signal (V) ・Neutron emission is isotropic. ・No significant energy shift. X rays Distance: 311 cm Angle: 80° Thermal neutrons X rays Distance: 178 cm Angle: 52° Flying time (ns)

  13. With the impact effect, neutron yield has been enhanced by a factor of about 100.

  14. Impact fast ignition has potential as an alternative approach to inertial fusion energy.

  15. Summary 1. Super-high velocity of 640 km/s has been achieved experimentally. 2. In-flight density of 0.2-0.8 g/cm3 has been achieved experimentally. 3. In the first integrated experiment, it was observed that neutron yield is enhanced by a factor of 100 due to the impact effect. 4. These results show that the Impact Fast Ignition has a high potential as another path way to laser fusion.

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