Grava Jonathan, Purvis Michael A, Filevich Jorge, Marconi Mario C, Rocca Jorge J, Dunn James, Moon Stephen J, Shlyaptsev Vyacheslav N
NSF ERC for Extreme Ultraviolet Science and Technology, and Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Jul;78(1 Pt 2):016403. doi: 10.1103/PhysRevE.78.016403. Epub 2008 Jul 17.
The formation and evolution of a collisional aluminum plasma jet created by optical laser irradiation of triangular grooves with pulses of 120ps duration at an intensity of 1x10(12)W cm(-2) were studied with experiments and simulations. Series of high-contrast soft x-ray laser interferograms obtained with a 46.9nm laser mapped the plasma density evolution of an initially narrow plasma jet that expands along the symmetry plane and evolves into a broader plasma plume with significant side lobes. Two-dimensional simulations performed using the radiation hydrodynamic code HYDRA reveal that the jet formation is initiated by accelerated material ablated from the vertex and is augmented by the continual sequential arrival of wall material along the symmetry plane, where it collides and is redirected outward. Radiative cooling is identified as an important process in maintaining the collimation of the jet. These results demonstrate that well collimated collisional plasma jets with parameters in a range of interest can be generated with low-energy laser pulses (<1J) , opening the possibility of studying relevant plasma phenomena in a small laboratory setting.
通过实验和模拟研究了在强度为1×10¹²W/cm²、持续时间为120ps的脉冲下，用光学激光照射三角形凹槽产生的碰撞铝等离子体射流的形成和演化。用46.9nm激光获得的一系列高对比度软X射线激光干涉图描绘了最初狭窄的等离子体射流的等离子体密度演化，该射流沿对称平面扩展并演变成具有明显旁瓣的更宽的等离子体羽流。使用辐射流体动力学代码HYDRA进行的二维模拟表明，射流的形成是由从顶点加速烧蚀的物质引发的，并通过壁材料沿对称平面的持续相继到达而增强，在对称平面处壁材料碰撞并向外重新定向。辐射冷却被认为是维持射流准直的一个重要过程。这些结果表明，利用低能量激光脉冲（<1J）可以产生参数在感兴趣范围内的准直良好的碰撞等离子体射流，这为在小型实验室环境中研究相关等离子体现象开辟了可能性。
