Roughness Optimization at High Modes for GDP CHx Microshells
- CEA, Commissariat a l'Energie Atomique (France)
For the ''Megajoule'' Laser (LMJ) facility of the CEA, amorphous hydrogenated carbon (a-C:H) is the nominal ablator to be used for inertial confinement fusion (ICF) experiments. These capsules contain the fusible deuterium-tritium mixture to achieve ignition. Coatings are prepared by glow discharge polymerization (GDP) with trans-2-butene and hydrogen. The films properties have been investigated. Laser fusion targets must have optimized characteristics: a diameter of about 2.4 mm for LMJ targets, a thickness up to 175 {mu}m, a sphericity and a thickness concentricity better than 99% and an outer and an inner roughness lower than 20 nm at high modes. The surface finish of these laser fusion targets must be extremely smooth to minimize hydrodynamic instabilities.Movchan and Demchishin, and later Thornton introduced a structure zone model (SZM) based on both evaporated and sputtered metals. They investigated the influence of base temperature and the sputtering gas pressure on structure and properties of thick polycrystalline coatings of nickel, titanium, tungsten, aluminum oxide. An original cross-sectional analysis by atomic force microscopy (AFM) allows amorphous materials characterization and permits to make an analogy between the amorphous GDP material and the existing model (SZM). The purpose of this work is to understand the relationship between the deposition parameters, the growing structures and the surface roughness.The coating structure as a function of deposition parameters was first studied on plane silicon substrates and then optimized on PAMS shells. By adjusting the coating parameters, the structures are modified, and in some case, the high modes roughness decreases dramatically.
- OSTI ID:
- 20849625
- Journal Information:
- Fusion Science and Technology, Journal Name: Fusion Science and Technology Journal Issue: 2 Vol. 45; ISSN 1536-1055
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINIUM OXIDES
ATOMIC FORCE MICROSCOPY
BUTENES
CARBON
DEPOSITION
DEUTERIUM
GLOW DISCHARGES
HYDROGEN
ICF DEVICES
INERTIAL CONFINEMENT
LASERS
NICKEL
POLYCRYSTALS
POLYMERIZATION
ROUGHNESS
SILICON
THERMONUCLEAR IGNITION
THERMONUCLEAR REACTOR MATERIALS
TITANIUM
TRITIUM
TUNGSTEN