Experiments on Parametric Instabilities in Laser-Plasma Interactions

  • Francis F. Chen
Part of the Nobel Symposium Committee (1976) book series (NOFS, volume 36)

Abstract

Recent experiments in laser-fusion laboratories have indicated the importance of non-classical processes in the absorption of intense laser radiation by solid targets. For instance, back-scattered light typically ranges from 10% to 50% of the incident intensity, larger than can be explained by classical reflection at the critical layer; and the excess has often been attributed to a parametric instability such as stimulated Brillouin or Raman scattering. Absorption of light—typically 40%—is lower than classical inverse bremsstrahlung in some experiments and higher in others. The parametric decay and OTS (oscillating two-stream) instabilities are supposed to occur near the critical layer to enhance the absorption. Even when classical processes are sufficient to explain the observed absorption, anomalous effects are indicated by the appearance of suprathermal electrons, as revealed by x-ray spectra. An even more serious effect is the generation of fast ions, which have in some instances accounted for as much as 80% of the absorbed energy. Acceleration of ions by electric fields generated in nonlinear processes has been conjectured. Finally, experiments on transmission through and fast ions from plastic foils have shown that heat conductivity is anomalously low, thus raising the possibility of large, self-generated magnetic fields.

Keywords

Plasma Focus Parametric Instability Ponderomotive Force Critical Layer Plasma Target 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1977

Authors and Affiliations

  • Francis F. Chen
    • 1
  1. 1.University of CaliforniaLos AngelesUSA

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