Thermal Effects and Erosion Rates from X - Ray Energy Deposition in Icf Reactor First Walls

The deposition of x-ray energy resulting from the microexplosion i.o an inertial confinement fusion reactor and the subsequent thermal response of candidate wall coating and structural materials is examined. Evaporation losses and resulting melt layer thicknesses for these materials exposed to a variety of different x-ray energies and spectra are calculated. Softer x-ray energy spectra absorbed very near the surface are found to cause more evaporation losses but less melting than harder spectra with the same energy content. Substantial differences in the thermal response exist among potential coating materials such as beryllium (low atomic number, low melting point) and molybdenun and tantalum (high atomic numbers, high melting points). It is found that beryllium can for a wide range of x-ray energy spectra expected in fusion reactors, resist vaporization losses and resulting melt layer and consequently prolong the lifetime of first walls more than molybdenun and tantalum.