Exploring Carbon New phases by Laser-Induced Shock Waves

通过激光诱导冲击波探索碳新相

基本信息

批准号：
08405044
负责人：
KONDO Ken-ichi
金额：
$ 20.35万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

Metastable phases of diamond, amorphous and nanocrystalline diamond, were produced by SCARQ (shock compression and rapid quenching) method based on the shock-gun technology, This method was also applied to a laser-shock technology, which was developed in this study. Two-types of laser-shock method were investigated ; one was the direct use of laser-induced ablation pressures, and the other was the use of the laser-driven flyer impact, For the latter, thin aluminum foils were accelerated by a high power Nd : YAG pulse laser and impacted PMMA window placed at a certain distance. Arrival time of the flyers was detected by a streak camera. Spatial changes in the arrival time revealed the curved flyer shape depending on the laser energy distribution which resulted in velocity distribution. Moreover, these profiles were strongly dependent on the distance from focal point of laser. Therefore, it was difficult to reduce the focal spot size less than 0.1 mm whose value was required for achieving the diamond transition pressure of 50 GPa. These experimental data were described by computer simulation based on one-dimensional hydro-code.The structural change of fullerene films subjected to laser-shock compression using the laser was investigated by Raman scattering. Some samples transformed into fullerene polymer, and the photo-induced structural change of fullerene was also investigated.An infrared radiometer for the accurate measurement of shock temperature was developed in order to investigate shock-induced, dynamic reaction processes of materials. To determine the IR-radiometer, the shock temperature measurements of carbon tetrachloride were conducted below 10 GPa, and the results confirmed that the system was available to measure relatively moderate shock temperatures lower than 1000 K.However, the system might be available at higher temperature in the case of laser-shock because of the small shock-compressed area.

基于冲击枪技术的 SCARQ（冲击压缩和快速淬火）方法生产了金刚石、非晶态和纳米晶金刚石的亚稳相，该方法也应用于本研究开发的激光冲击技术。研究了两种类型的激光冲击方法；一种是直接使用激光诱导烧蚀压力，另一种是使用激光驱动飞片冲击。对于后者，薄铝箔通过高功率 Nd:YAG 脉冲激光加速，并冲击放置在一定的距离。条纹相机检测传单的到达时间。到达时间的空间变化揭示了弯曲的飞片形状，这取决于导致速度分布的激光能量分布。此外，这些轮廓很大程度上取决于距激光焦点的距离。因此，很难将焦斑尺寸减小到小于 0.1 mm，而该值是实现 50 GPa 的金刚石转变压力所需的值。这些实验数据通过基于一维水代码的计算机模拟进行描述。通过拉曼散射研究了富勒烯薄膜在激光冲击压缩下的结构变化。一些样品转化为富勒烯聚合物，并研究了光引起的富勒烯结构变化。为了研究材料的冲击引起的动态反应过程，开发了一种精确测量冲击温度的红外辐射计。为了确定红外辐射计，四氯化碳的冲击温度测量在 10 GPa 以下进行，结果证实该系统可用于测量低于 1000 K 的相对中等的冲击温度。但是，该系统可能适用于更高的温度在激光冲击的情况下，由于冲击压缩面积小。