Direct measurement of laser irradiation uniformity of fusion pellets by the use of X-ray frame images

Time-resolved 2-dimensional (2D) X-ray images were taken to evaluate laser irradiation non-uniformity of fusion pellets. X-ray distributions corresponding to the drive laser geometry were obtained on the circumference of the image of a gold-coated surrogate target. The experimental results were analyzed to derive the irradiances by using an experimentally-determined relation between the laser irradiation intensity and the X-ray intensity. The analyzed results were compared with a laser illumination calculation in which temporally varying laser beams were projected onto a target sphere. A reasonable agreement between the measurement and calculation has been obtained.