RADIATIVE HEATING OF LOW-Z SOLID FOILS BY LASER-GENERATED X-RAYS

The x-ray emission and burnthrough of radiatively heated low-Z plastic foils (C8H8, nCH(2), or CF2) have been investigated in gold cavities of different shape and size, which were heated by the Gekko XII laser up to a radiation brightness temperature of 160 eV. The cavity radiati on temperatures were obtained spectroscopically as well as from the sp eed of the shock that is radiatively driven into aluminum. From measur ed carbon burnthrough spectra we derived mass ablation rates at drive temperatures ranging from 100 to 180 eV. In addition we measured tempo rally resolved reemission spectra of carbon. The time- and frequency-i ntegrated reemission was 23% of the gold reemission or 16% when normal ized to the driving cavity flux. The measurements are in good agreemen t with numerical hydrodynamic computer code simulations based on multi group radiation diffusion.