Fusion Science and Technology / Volume 49 / Number 4 / May 2006 / Pages 813-817
Technical Paper / Target Fabrication
In the last years, many applications of pulsed laser in precision machining have been demonstrated. Short pulse durations (nanosecond, picosecond and femtosecond) and short wavelength (U.V. and visible) create small heat-affected zones during the interaction with material such as polymers or metals. In the case of excimer lasers, energy carried by ultra-violet photon is sufficient to break apart molecular bonds without thermal effects, particularly in the case of the 3.7 eV C=H bond. All these properties facilitate high spatial resolution and high accuracy processes. This is especially true in the case of high absorbing carbon-hydrogen polymers.
An excimer multipulses engraving technique using time-resolved surface ablation was developped using our home-made laser micro-machining work station. This four-axis work station is composed of motor-controlled translation and rotation stages. This experimental set-up was designed to pattern 3D object by the mean of the association of rotative and translative motions. Sinusoidal recording on polystyrene, polyimide and GDP polymers about ten micrometers spatial frequency and a few micrometers amplitude were performed using binary masks with particular shapes.
Applications to hydrodynamics modes growth (which have detrimental effect on fusion burn in the "Megajoule laser" LMJ CH-GDP -shell) measurements will be performed on OMEGA laser facility.