首页   按字顺浏览 期刊浏览 卷期浏览 Self‐focusing and filamentation of laser light in highZplasmas
Self‐focusing and filamentation of laser light in highZplasmas

 

作者: R. D. Jones,   W. C. Mead,   S. V. Coggeshall,   C. H. Aldrich,   J. L. Norton,   G. D. Pollak,   J. M. Wallace,  

 

期刊: Physics of Fluids(00319171)  (AIP Available online 1988)
卷期: Volume 31, issue 5  

页码: 1249-1272

 

ISSN:0031-9171

 

年代: 1988

 

DOI:10.1063/1.866754

 

出版商: AIP

 

数据来源: AIP

 

摘要:

Self‐focusing and filamentation of short wavelength laser light in highZplasmas of interest to laser fusion are discussed. It is found that self‐focusing behavior is very dependent on the details of the characteristics of the laser beam, the plasma conditions, and the energy transport processes. Laser light absorption and self‐focusing are strongly competitive processes. At. 0.26 &mgr;m wavelength the collisional absorption is often so great that there is no intensity amplification of the beam despite the fact that strong self‐focusing is present. Wide variations are found in laser light penetration, affected by several factors. Diverging optics reduce the likelihood of self‐focusing. Large scale length density gradients have little effect on focusing behavior. The self‐focusing behavior is very dependent on beam shape. Large scale hot spots can have a significant effect on whole beam self‐focusing early in the pulse. The behavior of small scale hot spots can be qualitatively different than the standard picture. The calculations indicate that small scale hot spots do not achieve a steady state in some cases. Sound waves cause chaotic interactions among neighboring hot spots. It is found that sub‐beam size structures are also generated when nonlocal thermodynamic equilibrium (non‐LTE) radiation and atomic physics are used in the calculations. The nature of the heat flux and thermoelectric magnetic field generation are examined with a kinetic model. Stimulated Raman backscattering levels in self‐focused light are significantly reduced for short wavelengths and highZplasmas Landau damping plays an important role in determining the Raman levels. Implications for suprathermal electron production, symmetric illumination, x‐ray conversion efficiency, and laser light absorption are discussed.

 

点击下载:  PDF (3077KB)



返 回