Micromachining for laser fusion pellet

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.)