Peripheral Elements and Technology Associated with Pulsed Power Inertial Fusion

From the various peripheral elements and technology associated with pulsed power inertial fusion, we selected two kinds of subjects to discuss our future direction of the IFE reactor design in this paper. The first is reactor wall ablations with the implosion X-ray, and the second is a probable way to adopt medium-mass ion sources as the future candidate energy driver for the IFE reactor design. After the recent results concerning these topics are shown, the future plans are described briefly to promote the advanced studies in these fields. 1. Significance of Overall Problem and Long-range Objectives The fast pinch discharge can now transform the stored electrical energy into X-ray with very high efficiency as Sandia National Laboratories show. The pulsed ion beam with mediumweight is also interesting from the point of view of a candidate energy driver for IFE and the industrial application. These belong to the group of pulsed power inertial fusion. If the problem of the rep-rate operation of the pinch source will be solved, and if the tight focus of the medium-mass beam will be obtained, the power plant designs with both energy drivers will become more realistic in the near future. So that, we will try to investigate the peripheral elements and technology associated with these drivers. 2. Recent Results of Wall Material Ablation Induced by X-ray Associated with Target Implosion: Numerical Calculation The first subject in this paper is our numerical estimation of the wall ablation with the target implosion X-ray. Recently we started the preliminary calculation of the thickness of the wallmaterial which is ablated with the implosion. At first we gathered the necessary data for X-ray absorption as a function of radiation wavelength. Taking into account of the spectral distribution of the implosion Xray and the absorption data, we then obtained the absorbed Xray energy to estimate the evaporated wall thickness, for example. 2.1. Example of X-ray Produced by Laser-Target Implosion One example of laser target calculations is shown in reference [1]. When the laser energy of 3MJ hits a target with the energy gain of 148, we get nuclear fusion energy of 445MJ, X-ray energy of 4MJ, neutron energy of 303MJ and charged particle energy of 138MJ. The time history and the spectrum of the X-ray are shown in FIG. 1(a) and (b). The inner radius of the solid reactor wall is assumed to be 4m. Although the energy of X-ray is lower than the other ones, it hits the reactor wall at first and the peak power is highest among others. As this kind of X-ray may degrade the first wall of the inertial confinement fusion reactor, we estimated the ablated thickness of the solid wall. ______________________________ 1 Supported by the Ministry of Education, Science, Culture and Sports in Japan, the Japan Society for the Promotion of Sciences, Tokyo Institute of Technology, Sandia National Laboratories and Institute of Laser Engineering, Osaka University. 2 Collaborations with M.Funatsu, S.Saitoh, T.Kamiya (Tokyo Institute of Technology), T.Yamanaka, S.Nakai, K.Mima, H.Nishimura, Y.Kozaki (Osaka University), T.Renk, B.Turman, C.Olson, J.Quintenz (Sandia National Laboratories).