Measurement techniques development. Final report

This final report covers work done through the period of performance 16 January 1991 to 16 January 1993. The work has been in support of the drive symmetry and hydrodynamic implosion experiments which Lawrence Livermore National Laboratory (LLNL) Group P-4 is designing and fielding at the NOVA laser facility at LLNL. The work done involves experimental support in obtaining data, analysis of the data, and experimental design

Detailed diagnosis of double shell collision using X-ray radiography under realistic implosion conditions

In this work we will present the first measurement of the time history of a collision of two shells in a double shell capsule. Double shell implosions provide a non-cryogenic path to inertial confinement fusion [ICF]. In the double shell target the laser energy is absorbed in an outer shell that is accelerated inward which then, after the laser is off, collides with an inner shell. The inner shell then implodes against the deuterium fuel. We use radiography to diagnose the symmetry and the hydrodynamics of the implosion. At the OMEGA laser at LLE, we point 40 beams in an offset geometry to implode the doube shell target and use the remaining 20 beams to perform radiography from two different directions. This is the first measurement of such a collision in a spherical geometry and is of great interest to the verification of the code we used. In this work we will present the first measurement of the time history of a collision of two spherical shells in a double shell capsule

Reduced reshock growth in a convergent/divergent system: Effect of reshock strength

The Richtmyer-Meshkov instability creates or seeds hydrodynamic instabilities that will mix cold shell material into the hot DT fuel in an ignition capsule and may prevent ignition. Characteristic of this process is multiple shocks crossing converging interfaces. To mimic this situation, strong converging shocks were created, passed over an unstable interface, reflected by an inner cylinder, and then reshocked the interface. Analysis of the mix width at the unstable surface shows no additional growth, within experimental uncertainty, due to an initially perturbed surface and no dependence on reshock strength