For ultrafast material analyses, we constructed the time-resolved X-ray dif
fraction system utilizing ultrashort X-rays from laser-produced plasma gene
rated by the 12-TW-50-fs laser at the Nuclear Engineering Research Laborato
ry. Ultrafast transient changes in laser-irradiated GaAs crystals were obse
rved as X-ray diffraction patterns. Experimental results were compared with
numerical analyses.