| Research Abstract |
The purpose of the present study is to investigate the role of fusion-produced particles in ICF plasma, on the basis of multi-dimensional transport-hydrodynamic calculations. First, we developed two-dimensional transport and diffusion codes for alpha-particles, and verified usefulness of these codes in analyzing the effects of alpha-particle heating.
The developed diffusion code was coupled with a radiation-hydrodynamic code to investigate how and to what extent the hydrodynamic instability in the stagnation phase affects the ignition and burn property of compressed fuel spheres. As an initial condition, we assumed a fuel sphere at the stagnation phase and applied a sinusoidal single mode perturbation to the density, temperature and fluid velocity profiles in the boundary region between the hot spark and main fuel. It was confirmed that once a certain amount of fusion reactions occur in the spark region, the initial perturbations are drastically smoothed by the alpha-particle heating. It was also found that the amplitudes of the initial perturbations should be less than 5% of the hot spot radius in order to achieve a sufficient fuel gain (>1000).
In the latter half of the study, our attention was directed to the code plasma heating and ignition process in the fast ignition scheme. To this end, we developed a kinetic transport code for relativistic electrons. In addition to binary collisions at short range, we considered long-range collisions between screened particles. Given the source distribution of beam electrons entering the core region, the code is capable of calculating the time-and space-dependent plasma heating rate.
This code was coupled with a radiation-hydrodynamic one to analyze the core-plasma heating experiment carried out at Osaka Univ. The simulation explained the observed neutron production. Then, we examined the ignition and burn properties of compressed fuels of various sizes, and finally evaluated the gain curves.
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