COMPARISON OF DRIVE-SEEDED MODULATIONS IN PLANAR FOILS FOR 0.35 AND 0.53 MU-M LASER DRIVE

Laser-speckle-seeded modulations in laser-driven targets have been obs erved with the Nova laser using 0.53 and 0.35 mu m drive. The 0.35 mu m drive produced larger modulations (equivalent to 3.3 mu m rms surfac e finish) than 0.53 mu m drive (2.0 mu m rms). The laser intensity was similar to 10(13) W/cm(2), similar to that suggested for directly dri ven ignition targets during the first several ns. LASNEX simulations o f this thermal smoothing effect in both the rms and spectrum agree wit h the 0.53 mu m drive data, and are about 15% lower than the measured results with 0.35 mu m drive.