Controlling the Expansion of Laser-Fusion Plasma to Minimize Impact Damage
I propose to analytically model the rapid, nonequilibrium expansion of laser-fusion plasma from an initial diameter of 1 mm to a final diameter of 10 m. The aim is to devise a counterforce that minimizes the impact damage on optics by laser-plasma debris. This flow model is the basis of an idea for a dynamic target that efficiently converts laser energy to x-rays while minimizing the total mass propelled as debris. Also, the flow model is the basis of an idea to magnetically deflect material away from the optic ports in the vacuum chamber wall. The model combines results for supersonic one-dimensional gas flow of cylindrical-hemispherical symmetry, with a transition from thermal to nonequilibrium (''frozen'') plasma flow, which is set differently along each characteristic line (the ''Bray criterion'' as a Riemann invariant). The model shows how density, pressure, velocity, ionization fraction, electron temperature, and electrical conductivity vary over space and time, given an impulsively-heated source mass. The model is analytical, and examples are calculated on a desktop computer. This ease-of-use makes it possible to iterate quickly when refining ideas, such as a dynamic metal-vapor target that propels minimal debris, and a magnetohydrodynamic generator as a brake on the flow speed directed at the optic ports. The work involved here is that of an individual refining his analysis.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE Office of Defense Programs (DP) (US)
- DOE Contract Number:
- W-7405-Eng-48
- OSTI ID:
- 793849
- Report Number(s):
- UCRL-ID-136628; TRN: US200221%%112
- Resource Relation:
- Other Information: PBD: 18 Mar 1999
- Country of Publication:
- United States
- Language:
- English
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