MEASUREMENT OF SINGLE-MODE IMPRINT IN LASER ABLATIVE DRIVE OF A THIN AL FOIL BY EXTREME-ULTRAVIOLET LASER RADIOGRAPHY

The temporal development of laser driven single mode perturbations in thin A1 foils has been measured using extreme ultraviolet (XUV) laser radiography. 15, 30, 70 and 90 mu m single modes were imprinted on 2 m u m thick A1 foils with an optical driver laser at 527 nm for intensit ies in the range 5 x 10(12) to 1.5 x 10(13) W cm(-2). The magnitude of the imprinted perturbation at the time of shock break out was determi ned by fitting to the data estimated curves of growth of the Rayleigh- Taylor instability after shock break out. The efficiency of imprinting is independent of perturbation wavelength in the parameter range of t his experiment, suggesting little influence of thermal conduction smoo thing. The results are of interest for directly driven inertially conf ined fusion. (C) 1998 American Institute of Physics.