Cylindrical implosion experiments using laser direct drive

Direct-drive cylindrical-implosion experiments are performed to study pertu rbed hydrodynamic flows in convergent geometry. Two experimental campaigns have been conducted, to demonstrate the advantages of direct over indirect drive and to validate numerical simulations of zeroth-order hydrodynamics a nd single-mode perturbation growth. Results and analysis of three unperturb ed-target shots and two perturbed-target shots are discussed in detail. For unperturbed-target implosions, positions of inner and outer shell edges ag ree between simulation and experiment during the laser pulse. However, obse rved shell thickness is greater than simulated in unperturbed targets durin g deceleration and rebound; the effect appears only at the shell's exterior edge. For perturbed-target implosions, growth factors similar to 10-14 are observed, whereas growth factors near 30 are expected from simulation. Ray leigh-Taylor growth appears to differ between simulation and experiment. Ob served zeroth-order flow at the exterior edge of imploding, perturbed targe ts appears to differ from simulation, even during acceleration. A possible physical model to explain such apparent differences is identified. (C) 1999 American Institute of Physics. [S1070-664X(99)96105-0].