Improved Performance of Direct-Drive Inertial Confinement Fusion Target Designs with Adiabat Shaping Using an Intensity Picket
(B204)Hydrodynamic instabilities seeded by laser imprint and surface roughness limit the compression ratio and neutron yield in the direct-drive inertial confinement fusion target designs. New improved-performance designs use adiabat shaping to increase the entropy of only the outer portion of the shell, reducing the instability growth. The inner portion of the shell is kept on a lower entropy to maximize shell compressibility. The adiabat shaping is implemented using a high-intensity picket in front of the main-drive pulse. The picket launches a strong shock that decays as it propagates through the shell. This increases the ablation velocity and reduces the Rayleigh-Taylor growth rates. In addition, as shown earlier [T.J.B. Collis and S. Skupsky, Phys. Plasmas 9 275 (2002)], the picket reduces the instability seed due to the laser imprint. To test the results of calculations, a series of the picket pulse implosions of CH capsules were performed on the OMEGA laser system [T.R. Boehly, D .L. Brown, R.S. Craxton, et al., Opt. Commun. 133, 495 (1997)]. The experiments demonstrated a significant improvement in target yields for the pulses with the picket compared to the pulses without the picket. Results of the theory and experiments with adiabat shaping are being extended to future OMEGA and the National Ignition Facility's [J.A. Paisner, J.D. Boyes, S.A. Kumpan, W.H. Lowdermilk, and M.S. Sorem, Laser Focus World 30, 75 (1994)] cryogenic target designs.
- Research Organization:
- Laboratory for Laser Energetics (US)
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- FC03-92SF19460
- OSTI ID:
- 810677
- Report Number(s):
- DE/SF-19460-486; 1359; 2003-71; TRN: US200312%%304
- Journal Information:
- Physics of Plasmas, Vol. 10, Issue 5; Other Information: Submitted to the Physics of Plasmas; Volume 10, No.5 (7 May 2003); PBD: 7 May 2003
- Country of Publication:
- United States
- Language:
- English
Similar Records
Improved target stability using picket pulses to increase and shape the ablator adiabat
Increasing robustness of indirect drive capsule designs against short wavelength hydrodynamic instabilities