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

Abstract

Self-supporting ultralow density laser targets with an apparent density as low as 1 mg/cm³, a porous layer thickness of 60–500 μm, 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–60°C and lower, down to–190°C, without initial gelation.