Currently there is considerable interest in creating scalable laboratory plasmas to study the mechanisms behind the formation and evolution of astrophysical phenomena such as Herbig-Haro objects and supernova remnants. Laboratory-scaled experiments can provide a well diagnosed and repeatable supplement to direct observations of these extraterrestrial objects if they meet similarity criteria demonstrating that the same physics govern both systems. Here, we present a study on the role of collision and cooling rates on shock formation using colliding jets from opposed conical wire arrays on a compact pulsed-power driver. These diverse conditions were achieved by changing the wire material feeding the jets, since the ion-ion mean free path (${\lambda }_{\text{mfp-ii}}$) and radiative cooling rates ($P_{\mathrm{rad}}$) increase with atomic number. Low $Z$ carbon flows produced smooth, temporally stable shocks. Weakly collisional, moderately cooled aluminum flows produced strong shocks that developed signs of thermal condensation instabilities and turbulence. Weakly collisional, strongly cooled copper flows collided to form thin shocks that developed inconsistently and fragmented. Effectively collisionless, strongly cooled tungsten flows interpenetrated, producing long axial density perturbations.

中文翻译：

---

碰撞性和辐射冷却在不同材料的超声等离子体射流碰撞中的作用

当前，人们对创建可扩展的实验室等离子体以研究天文学现象（例如Herbig-Haro物体和超新星遗迹）的形成和演化背后的机制非常感兴趣。如果这些实验室的天体符合相似标准，说明两个系统的物理原理相同，则实验室规模的实验可以为直接观察这些天体提供良好的诊断和可重复的补充。在这里，我们介绍了一种紧凑型脉冲功率驱动器上的对撞和冷却速度对冲击形成的作用的研究，该冲击是使用来自相反圆锥形线阵列的碰撞射流产生的。由于离子-离子的平均自由程（${\lambda }_{\text{mfp-ii}}$）和辐射冷却速率（$P_{\mathrm{拉德}}$）随着原子序数的增加而增加。低$ž$碳流产生了平稳的，暂时稳定的冲击。弱碰撞，中度冷却的铝流产生强烈的冲击，形成热冷凝不稳定性和湍流的迹象。弱碰撞，强烈冷却的铜流相撞，形成了薄弱的冲击，并不一致地发展并分散了。有效地无碰撞，强冷却的钨流相互渗透，从而产生长的轴向密度扰动。