The Twelfth IAEA Conference on Plasma Physics and Controlled Nuclear Fusion Research featured some seventy tokamak experimental papers, pertaining to every issue of tokamak physics. While previous conferences have sometimes been dominated by a single result, for example achievement of high nτ or T-values, such was not the case of the Nice meeting. Rather, this conference was characterized by a multitude of excellent scientific results on virtually all aspects of tokamak behaviour: confinement, operational limits such as density and beta MHD stability, heating, current drive and, to a lesser extent, impurity control. Taken together, these results lay a solid foundation for continued progress and future steps.

No abstract

No abstract

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 jim). Symmetry was proved to be controlled by the casing structure, following scaling laws describing hohlraum physics. A compressed DT densitỹ 100 p 0 (fio 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.

Pulses of 20 TW have been generated at 1064 nm using the chirped pulse amplification technique coupled to a 90 mm output aperture Nd–silicate glass amplification line. The chirped pulses are compressed to 1.2 psec with an energy of 24 J using large holographic gold-coated 1740 lines/mm diffraction gratings. In a first step, the beam is focused by an aspherical lens, but the maximum measured irradiance is limited to 1018 W/cm2 by self-focusing effects in the air path and in the lens. Higher values up to 1019 W/cm2 will need propagation of the compressed beam in vacuum and focusing by reflective optics. The first experiments deal with laser–plasma coupling, with emphasis on the power contrast ratio. Further plans include multiple Compton scattering and x-ray laser generation. Theoretical works on ionization processes and particle accelerator are also presented.