This study provides a detailed investigation into the collision process of high-energy-density plasma clusters, a critical phenomenon in both astrophysics and inertial confinement fusion physics. Utilizing the advanced hybrid fluid-PIC simulation tool ASCENT-H within a quasi-one-dimensional planar model framework, we have conducted a comprehensive analysis of interpenetration effect and energy conversion mechanisms during the collision of two high-energy-density plasma clusters. The results indicate that the state of the interstitial plasma significantly influences the interaction time and energy distribution during the collision process. In low-density regions, due to weak collision effects, ions propagate freely along stable trajectories while maintaining high kinetic energy, making the interpenetration phenomenon more pronounced. However, as interpenetration progresses, the electron pressure gradient and space electric field weaken, forming a feedback regulation mechanism with the density gradient. During this process, the ion mean free path becomes relatively long, preventing complete kinetic energy conversion in the core region and instead depositing energy in the distal region. This results in a lower ion temperature peak and a broadened, asymmetric temperature distribution. In contrast, in high-density regions, frequent collisions accelerate energy homogenization, effectively validating the local thermal equilibrium assumption of the fluid model in this regime, which aligns well with the results of kinetic simulations. These findings not only advance our fundamental understanding of plasma collision processes but also significantly enhance the predictive capabilities for laser-driven fusion implosion scenarios.

Plasma Collision,Interpenetration effect,Hybrid fluid-PIC model