Impact of nonlocal electron heat transport on ablative hydrodynamic instability growth seeded by localized perturbations

Abstract The hydrodynamic instability growth seeded by localized perturbations exerts a significant influence on the performance of inertial confinement fusion implosions. Direct-drive, planar target ablative hydrodynamic instability growth simulations were performed to study the evolution of localized perturbations at peak drive intensities of ignition designs. The study focused on hydrodynamic instability seeded by Gaussian bumps and rectangular pits on the target outer surface at a laser intensity of about <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>9</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mn>14</mml:mn> </mml:mrow> </mml:msup> <mml:mstyle scriptlevel="0"/> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">W</mml:mi> <mml:mstyle scriptlevel="0"/> <mml:mi>cm</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> . The findings indicated that the nonlinear growth of localized perturbations is significantly influenced by nonlocal electron heat transport. It was observed that the small-scale Gaussian bump experiences a phase reversal before the target acceleration phase and evolves into an isolated bubble, with spikes growing obliquely on both sides tending to heal the void created by the bubble. Notably, nonlocal electron heat transport effects slow down void healing and nonlinear bubble growth, which can prevent defects from penetrating the target shell prematurely. For rectangular pits with larger lateral dimensions, no overall phase reversal occurs before target acceleration, and the nonlinear bubble growth is similarly suppressed. These findings underscore the importance of considering nonlocal electron heat transport effects in multi-dimensional implosion simulations.