Influence of capsule support tent on ICF DD gas implosion performance is investigated with a two-dimensional radiation diffusion hydrodynamic code LARED-S. It shows that the support tent reduces significantly the neutron yield with a YOC (yield over clean) of 55.2%. The main degradation mechanism is that the capsule shell produces high-amplitude high-density spikes, penetrating deep into the central DD gas. It increases greatly power loss due to electron conduction on the CH/DD interface, leading to the rapid reduction of DD reaction rate and final neutron yield. Compared with one-dimensional ideal implosion simulation result, bang-time of the two-dimensional tent simulation is apparently earlier, and perturbations introduced by the capsule support tent reduce the central pressure and internal energy of DD gas, which is converted from the shell implosion kinetic energy.

We perform 2D ignition capsule implosion simulation by a 2D multi-group radiation diffusion hydrodynamic code LARED-S which simultaneously simulates radiation drive asymmetry and outer surface roughness. Implosion flow field shows large-amplitude spikes and bubbles as well as a significant low-mode shell areal density asymmetry. Amplitudes of modes generated by mode coupling are in good agreement with analytic mode coupling equation until perturbation amplitude of fundamental mode L24 is greater than nonlinear saturation amplitude. In deceleration phase, perturbation growth is in strong nonlinear phase, and strong mode coupling effects broaden mode distribution. High-density spikes are bent by vortex flow. Mode coupling degrades greatly implosion performance, leading to ignition failure. Further simulations of mode coupling between low-mode drive asymmetry and capsule surface roughness is critical for understanding influences of hydrodynamic instabilities on ignition capsule implosion.

High-foot high-adiabat implosion simulations of ICF ignition capsules are performed with one-dimensional multi-group radiation transport hydrodynamic code RDMG and two-dimensional few-group radiation diffusion hydrodynamic code LARED-S. Compared with low-adiabat implosion, high-foot implosions improve significantly stability of ablation front and ablator-fuel interface by increasing radiation drive temperature of the foot, leading to great reduction of hydrodynamic instability growth and hot-spot mix. Meanwhile, high-foot implosion decrease DT fuel compression. Final compression density and areal density of the main fuel at stagnation are decreased, causing lower neutron yield. A better stability of high-foot high-adiabat implosion is obtained at cost of reducing DT fuel compression.