Uniformity and stability issues are investigated for three phases of a laser implosion process: startup, acceleration and stagnation. hydrodynamic perturbation growth in the startup phase seeds the Rayleigh-Taylor (RT) instability in the subsequent phases. An analytical model is developed to study the propagation of a rippled shock and the deformation of an ablation surface driven by non-uniform laser ablation. Agreement between theory and experiment is found in the propagation of the shock front ripple and also in areal mass density perturbation. A new instability of the uniform contact surface is found to be driven by the rippled shock. For both linear and non-linear cases, the growth rate depends on the phase of the oscillating shock wave at the time when the shock hits-the contact surface. Exact analytical solutions of the linear growth rates for the Richtnyer-Meshkov instability are found for both reflected shock and reflected rare action cases. They agree well with recent experiments. Two dimensional (2-D) Fokker=-Planck heat transport is introduced in a 2-D hydrodynamic code to study the RT instability at the ablation surface. non-local heat transport is shown to play an important rolein reducing the growth rate. 2-D simulations are also carried out to study the neutron yield reduction observed in the GEKKO XII laser implosion experiments. It is found that odd number-uniformity is dominant in repelling the fuel from the centre and in reducing the neutron yield. A new type of self-similar solution, which determines the stagnation dynamics, is obtained, and the density gradient generated by the conduction is shown to reduce the RT growth.
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