Experiments on energy redistribution by thermal radiation in cylindrical cavities

Experiments are presented that demonstrate the process leading to isotropization of the radiation field in a cavity heated by thermal x rays. Gold, cylindrical cavities 500 [mu]m in diameter were heated from one side by [congruent]154 eV thermal radiation from a laser plasma. The effect of the reemission in transporting energy along the cylinder axis was ascertained by comparing the axial temperature profile of open'' and closed'' geometry targets. The results are in good agreement with a theoretical model for the redistribution of energy via absorption and re-emission of thermal radiation.