Characterization of heat transport dynamics in laser-produced plasmas using collective Thomson scattering: Simulation and proposed experiment
- Sandia National Labs., Albuquerque, NM (United States)
- Lawrence Livermore National Lab., CA (United States)
The authors propose an experiment in which the collective Thomson scattering lineshape obtained from ion acoustic waves is used to infer the spatial structure of local heat transport parameters and collisionality in a laser-produced plasma. The peak-height asymmetry in the ion acoustic wave spectrum will be used in conjunction with a recently developed model describing the effects of collisional and Landau damping contributions on the low-frequency electron density fluctuation spectrum to extract the relative electron drift velocity. This drift arises from temperature gradients in the plasma. The local heat flux, which is proportional to the drift, can then be estimated, and the electron thermal conductivity will be inferred from the relationship between the calculated heat flux and the experimentally determined temperature gradient. Damping of the entropy wave component at zero mode frequency is shown to be an estimate of the ion thermal conductivity, and its visibility is a direct measure of the ion-ion mean free path. The authors also propose to measure thermal transport parameters under dynamic conditions in which the plasma is heated impulsively by a laser beam on a fast ({approximately}50 ps) time scale. This technique will enable the authors to study heat transport in the presence of the large temperature gradients that are generated by this local heating mechanism. Deviations of the inferred local thermal conductivity from its Spitzer-Haerm value can be used to study the transition to the nonlocal heat transport regime. The authors have constructed a simple numerical model of this proposed experiment and present the results of a simulation. 41 refs., 9 figs.
- Research Organization:
- Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
- DOE Contract Number:
- AC04-94AL85000; W-7405-ENG-48
- OSTI ID:
- 415012
- Journal Information:
- Journal of Fusion Energy, Vol. 14, Issue 4; Other Information: PBD: Dec 1995
- Country of Publication:
- United States
- Language:
- English
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