REDUCTION OF RADIATION ASYMMETRY WITH RADIATION SHIELDS IN INDIRECTLYDRIVEN INERTIAL CONFINEMENT FUSION HOHLRAUM TARGETS

Using a relatively simple static model and allowing a number of additi onal radiation shields in an axially symmetric hohlraum having two con verters, a systematic process of reducing the asymmetry of the radiati on field on a fusion capsule is presented. As a result of this procedu re, a hohlraum target is obtained that shows a high degree of symmetri zation even in a very early stage of irradiation. The sensitivity of t he symmetry to the form and the position of each hohlraum component is investigated. To increase the reliability of the results, an enhanced model of radiation reemission in a hohlraum target, including reemiss ion of the converter is developed. Using this enhanced model it is fou nd that the obtained hohlraum configuration is still valid, while the simple reemission model leads to incorrect results in special cases. I t is also shown that the detailed configuration of a hohlraum target, especially of the radiation shields, depends considerably on the tempe rature distribution of the converter surface, but it is always possibl e to achieve a high degree of symmetry with radiation shields.