화학공학소재연구정보센터
Journal of Vacuum Science & Technology A, Vol.19, No.1, 118-123, 2001
Doped CHx microshells prepared by radio frequency plasma enhanced chemical vapor deposition for inertial confinement fusion experiments
French targets prepared for inertial confinement fusion experiments, to be shot on the Laser Megajoule facility, are organic (CHx) microshells. The microshell, that contains the deuterium-tritium mixture (DT), is placed in a gold holraum that converts the laser light into an x-ray flow. It is an indirect drive to reach ignition. This microshell, whose role is an ablator to initiate compression of the target, is fabricated by plasma polymerization of organic precursors. In these implosion experiments, it is necessary to control the preheat of the deuterium-tritium fusible mixture in the capsule, and the ablation front instability, by doping the ablator layer with a small quantity of high Z material. The germanium or bromine doping of the CHx enables the control of the microshell opacity to prevent the preheat of DT from high energetic x rays. Titanium is used to diagnostises the implosion of the target. The coating properties evolve with the amount of dopant incorporated in the CHx matrix. Evolution of the deposition rate, the roughness, the thermal stability, or the optical gap (UV/visible spectroscopy) are studied in this article. Concentration and homogeneity of the dopants are also determined as well as the chemical bindings between the dopants and the hydrocarbon matrix. Many characterizations are done by scanning electron microscopy, Rutherford backscattering spectroscopy, x-ray photoelectron spectroscopy, or Fourier-transform infrared.