[en] A hollow foam sphere is completely immersed in liquid heavy hydrogen fuels and heated externally. Liquid impregnated to the inside of the hollow sphere driven out by the heating step. Accordingly, it is possible to prepare a target in which liquid fuel is impregnated only to the portion of the foam wall. Further, according to the fuel charging device for the cryogenic form target of this invention, fuel gas is liquefied and the form hollow foam sphere is completely immersed in the liquefied fuel. Subsequently, the hollow foam sphere is heated by the heating device to drive out the liquids impregnated to the inside of the hollow sphere. Accordingly, it is possible to manufacture a target in which the liquefied fuel is impregnated only to the portion of the foam wall. As a result, an appropriate amount of fuel can be charged uniformly only at the portion of the foam wall. Further, this is also applicable to mass production of targets in near future. (I.S.)

[en] The present report describes ultralow density (2∼10 mg/cm³) hydrocarbon plastic (CH₂) foams with a controllable micro- or nano-meter-sized lamella structure. These foams are prepared from a poly(4-methyl-1-pentene) gel with hexanol and butanol derivatives by extraction using supercritical fluid CO₂. Their intended use is in laser-plasma experiments and as a laser-plasma X-ray source. Their microstructure approached to nanometer and was varied using different alcohols. The finest ultralow density foam was prepared from 2-butanol gel

No abstract available

[en] Cryogenic targets which have uniform liquid or solid fuel layers on the inner surfaces of their capsules are promising candidate for inertial confinement fusion targets. Techniques to make the uniform fuel layer under existing of the gravity include foam, beta heating and plasma heating techniques. These techniques are reviewed on a view point of use in near future implosion experiments. (author)

[en] Historical aspect, current status, and future prospect of elemental research of laser fusion target are reported including fabrication of fuel capsules, cryogenic technologies to make a uniform solid DT layer, and coating technologies. (author)

No abstract available

[en] Smooth and highly spherical capsule fabrication methods, the ablation-controlled functional surface materials and very low density porous materials, which are used for the laser fusion target, are described. The plastic capsule is made of poly(α-methylstyrene) (PAMS), polymethyl methacrylate and polyimide by a density-matched emulsion method. Glow Discharge Polymer (GDP) capsule was made by coating method using PAMS as mandrel. Very low temperature deuterium capsule is made by β-heating method, plasma heating method, IR-heating method and foam-cryo method. Cone guide type laser fusion target was observed by adding heat to plasma until 10⁷ degree. Porous plastic for laser target is made by three methods such as volatile solvent mixing method, freeze de aeration method and aerogel method. A nanometer level precise target is prepared by monolayer film adhesion method. (S.Y.)

[en] In laser nuclear fusion, the fusion reaction is induced by irradiating powerful laser beam on the pellets filled with fuel, and compressing and heating the fuel by implosion. At this time, in order to compress it up to high density, it is very important to compress as the spherical symmetry is maintained. The uniformity of the sphericity and wall thickness is required to be more than 98 %. Besides, in order to heighten the efficiency, it is necessary to limit the temperature of main fuel low, to ignite with hot sparks at the center, and to burn remaining fuel with the alpha particles which are generated by the nuclear fusion reaction there. For this purpose, various target structures have been proposed. The cryogenic target for ablative compression, the double shell target and the cannonball target are shown. In order to produce these targets, the development of the fuel spheres which have high uniformity and good sphericity in the required size, the development of the coating process with good surface finish which can do uniform coating at the rate of about 10 μm/h, the development of micromachining technology, the development of cryogenic technology and so on are necessary. Also the levitation of pellets by magnetic suspension method is explained. (K.I.)

[en] A uniform laser ablation was observed in a polystyrene film coated with a photovoltaic perylene/phthalocyanine bilayer when an incident took place at an intensity range of 10⁹-10¹⁰ W/cm² (λ=1064 nm, 1.1 ns FWHM). Without the bilayer coating, the laser pulse formed spiky structures in the polystyrene film as self-focusing traces of the laser pulse, while for the coated film, the uniform surface ablation trace without the spiky interior structures was observed. In the case of incident of 532 nm where the coating material exhibits no reflection, such difference depending the coating was not observed. These phenomena were coupled with the reflection and conduction properties via its photovoltaic effect, and agreed with the required ablation to achieve high-density compression of the fuel capsule for inertial fusion energy (IFE)

[en] Current topics on target fabrication for ignition and burn experiments using next generation lasers are discussed. Fabrication of plastic shells with high sphericity and wall uniformity is necessary to achieve implosions with high energy gain. Such targets will have a uniform solid or liquid fuel layer inside using either beta layering, plasma layering or foam method. (author)