Illumination stability for high-repetition-rate laser facilities in direct-drive inertial confinement fusion
Dipartimento SBAI, Università degli Studi di Roma “La Sapienza” and CNISM - via A. Scarpa 14, 00161, Roma, Italy, EU
Accepted: 1 April 2011
The illumination uniformity of a spherical target is of fundamental importance in direct-drive inertial confinement fusion. The laser intensity asymmetry is studied here using numerical calculations, taking into account target positioning errors and laser system shot-to-shot fluctuations. The optimisation of a laser beam configuration is outlined on the basis of a statistical analysis of the illumination uniformity using three independent selection criteria. The particular case of a 48-beam laser facility is discussed in detail. It is found that the fluctuation of the illumination asymmetry is a key parameter for assessing the stability of operation in high-repetition-rate mode. Moreover the target positioning error arising from the injection system could be the dominant source of illumination asymmetry in a fusion reactor.
PACS: 52.57.-z – Laser inertial confinement / 52.57.Fg – Implosion symmetry and hydrodynamic instability (Rayleigh-Taylor, Richtmyer-Meshkov, imprint, etc.) / 42.60.Jf – Beam characteristics: profile, intensity, and power; spatial pattern formation
© EPLA, 2011