Use of freezing techniques for increasing the output of ultralow density laser targets

摘要

Self-supporting ultralow density laser targets with an apparent density as low as 1 mg/cm(3), a porous layer thickness of 60-500 mu m, and a window diameter of 2.5 mm were prepared by thermally induced gelation of cellulose acetate solution in a mixture solvent between two glass slides using the mold casting method. In view of the low mechanical gel strength at a concentration of < 0.2 wt %, supercritical drying of molded targets is carried out without separating the glass slides. For the target output to be radically increased, a new procedure has been developed based on rapid freezing of the solution on a metal brick from room temperature to-60A degrees C and lower, down to-190A degrees C, without initial gelation.