2 results
Progress in inertial confinement fusion physics at Centre d'Etudes de Limeil-Valenton
- M. André, D. Babonneau, C. Bayer, M. Bernard, J-L. Bocher, J. Bruneau, A. Coudeville, J. Coutant, R. Dautray, A. Decoster, M. Decroisette, D. Desenne, J-M. Dufour, J-P. Garçonnet, P-A. Holstein, J-P. Jadaud, A. Jolas, D. Juraszek, J. Lachkar, P. Lascaux, J-P. Le Breton, M. Louis-Jacquet, B. Meyer, F. Mucchielli, C. Rousseaux, D. Schirmann, G. Schurtz, D. Véron, J-P. Watteau
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- Journal:
- Laser and Particle Beams / Volume 12 / Issue 3 / September 1994
- Published online by Cambridge University Press:
- 09 March 2009, pp. 329-342
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- Article
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The laser program developed at the Centre d'Etudes de Limeil-Valenton, Saint-Georges, France (CEL-V) is concentrated on a systematic investigation of indirect drive fusion; by comparison with direct drive, this process is expected to provide the required irradiation uniformity with relaxed constraints on laser beam quality. The main concerns are radiative transfer and preheat, hydrodynamic instabilities, and high-density X-ray driven implosions. Ablative implosion experiments have been conducted with the two beams at the Phebus facility (5 kJ, 1.3 ns, 0.35 μm). Symmetry was proved to be controlled by the casing structure, following scaling laws describing hohlraum physics. A compressed DT density ∼100 ρ0 (ρ0 liquid DT density) has been deduced from activation measurements. Different aspects of the soft X-ray transfer processes, and particularly of the ablation of a low-Z material, which drives the capsule implosion, are dealt with in detailed investigations. Reported here are results on X-ray reemission and penetration in several materials, and on induced hydrodynamics of accelerated foils. The laser energy required to reach fuel ignition conditions has been evaluated from numerical simulations as well as from analytical models, taking into account hohlraum physics, capsule implosion, hot spot formation, and burn propagation. Several crucial parameters have been drawn, the most important being the radiation temperature. A target gain in the order of 10 appears achievable with a 2-MJ laser.
ICF-related experiments at CEL-V
- M. Andre, C. Bayer, D. Babonneau, M. Bernard, J. L. Bocher, J. Bruneau, A. Coudeville, J. Coutant, R. Dautray, A. Decoster, M. Decroisette, D. Desenne, B. Duborgel, J. M. Dufour, J. P. Jadaud, D. Juraszek, J. P. Garçonnet, P. A. Holstein, J. Lachkar, M. Louis-Jacquet, F. Mucchielli, B. Meyer, J. P. Lebreton, J. Ouvry, D. Schirmann, G. Schurtz, D. Véron, J. P. Watteau
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- Journal:
- Laser and Particle Beams / Volume 10 / Issue 4 / December 1992
- Published online by Cambridge University Press:
- 09 March 2009, pp. 557-571
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Implosion experiments performed at Centre d'Etudes de Limeil-Valenton in the indirect drive scheme using the two-beams Nd:glass laser facility Phebus at the energy level = 6 kJ (blue light) are presented. A final density of compressed DT close to 100 ρ0 has been obtained; it has been deduced from radiochemistry of the activated silicon atoms in the pusher. The best irradiance uniformity on the microballoon was evaluated to = 15% rms. Phebus has also been equipped with an optical fiber oscillator to study the effect of a smoothing technique on coupling processes: It appeared that at 0·53 μm absorption efficiency is increased by =15–20%. With the eight-beams Octal laser, hydrodynamic instabilities development in accelerated planar targets has been investigated both for direct and indirect drives; the mixing zone detected at the light-heavy interface does not present visible bubble-and-spike like structures and is less developed in the indirect configuration. Atomic physics in laser plasmas is also deeply studied; a particular effort has been made on absorption spectroscopy, a powerful diagnostic of ionization dynamics in cold and dense plasmas. Experiments have been realized either in multilayered targets or using rear-side X-ray emission of thin Au foils to heat the samples. To reach fuel ignition conditions, more powerful lasers, in the range of megajoule, will be needed. Their design needs further technological developments to reduce the capital cost in $/W. At Limeil, we work mainly on high-damage threshold optical coatings, using the sol-gel process, high-quality, low-cost mirror fabrication, using the replica technics, and incoherent laser pulse generation for beam smoothing.