Crossed-beam energy transfer in direct-drive implosions
Direct-drive-implosion experiments on the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] have showed discrepancies between simulations of the scattered (non-absorbed) light levels and measured ones that indicate the presence of a mechanism that reduces laser coupling efficiency by 10%-20%. This appears to be due to crossed-beam energy transfer (CBET) that involves electromagnetic-seeded, low-gain stimulated Brillouin scattering. CBET scatters energy from the central portion of the incoming light beam to outgoing light, reducing the laser absorption and hydrodynamic efficiency of implosions. One-dimensional hydrodynamic simulations including CBET show good agreement with all observables in implosion experiments on OMEGA. Three strategies to mitigate CBET and improve laser coupling are considered: the use of narrow beams, multicolor lasers, and higher-Z ablators. Experiments on OMEGA using narrow beams have demonstrated improvements in implosion performance.
- Research Organization:
- Laboratory for Laser Energetics, University of Rochester, Rochester, NY
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FC52-08NA28302
- OSTI ID:
- 1043686
- Report Number(s):
- DOE/NA/28302-1063; 2011-122; 2040
- Journal Information:
- PHYSICS OF PLASMAS, Vol. 19
- Country of Publication:
- United States
- Language:
- English
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Crossed-beam energy transfer in direct-drive implosions
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